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ITemplate - Dynamic ImageButton in BindLabelColumn for DataListI am trying to dynamically generate an ImageButton in a datalist label column. When I have a static reference to the image 'image/plus.gif', the image is displayed in the label column. However, when I try to adapt the html code to be dynamically defined in the binding of the label column, the image is not displayed. Below is the sub BindParentLabelColumn where the label text is assigned. Any insight on the issue is greatly appreciated - I am stumped. Thank you, Erik Public Sub BindParentLabelColumn(ByVal sender As Object, ByVal e As EventArgs) Dim lbl As Label = CType(sender, Label) Dim strvals As String Dim container As DataListItem = CType(lbl.NamingContainer, DataListItem) Dim dt As DataTable = Session("DataList_ParentDetailControls") Dim dc As DataColumn Dim sColumnValue As String Dim sColumnName As String strvals = "<tr>" For Each dc In dt.Columns sColumnName = dc.ColumnName sColumnValue = Convert.ToString(DataBinder.Eval(CType(container, DataListItem).DataItem, dc.ColumnName)) strvals &= "<TD align='center' width='10'><asp:ImageButton ID='Expand" + sColumnName + "' runat='server' CommandName='Select" + sColumnName + "' ImageUrl='images/plus.gif'></asp:ImageButton></TD>" & _ "<TD align='center' width='80'>" + sColumnValue + "</TD>" End If Next strvals &= "</tr>" lbl.Text = strvals End Sub 'BindParentLabelColumn Hi Erik,
Good morning to you too and welcome back to the newsgroup. Regarding your code: 1- Server control markup renders into HTML markup when it is processed by the ASP.NET engine. But when you placed it inside the label text, the label control will assume that is a regular HTML markup and would not translate it from being server control markup to HTML 2- The BindParentLabelColumn would not execute unless you add an event hanlder to the lable.databinding event. You could have also wrote the logic within the DataList.ItemDataBound event to achieve the same outcome. 3- If you want your page to handle the click events of the dynamically created image buttons you should databind the list during the Page.Init stage. Here is how I would modify your code: 'starting during the initialization phase of the page's lifecycle Private Sub Page_Init(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Init InitializeComponent() 'Dynamically created controls should be created during the 'page initializtion stage for the control to maintain their viewstate BindControls() End Sub Private Sub BindControls() 'Explicity cast the session variable to its appropriate type before using it datalist1.DataSource = CType(Session("DataList_ParentDetailControls"), DataTable) datalist1.DataBind() End Sub Private Sub DataList1_ItemCreated(ByVal sender As Object, ByVal e As DataListItemEventArgs) Handles datalist1.ItemCreated Dim myLabel As Label = e.Item.FindControl("Label1") 'this step wires up the label databinding event to a method AddHandler myLabel.DataBinding, AddressOf BindParentLabelColumn End Sub Public Sub BindParentLabelColumn(ByVal sender As Object, ByVal e As EventArgs) Dim lbl As Label = CType(sender, Label) Dim container As DataListItem = CType(lbl.NamingContainer, DataListItem) 'the datalistitem has a pointer to the DataItem (which is datarowview) 'of your datatable. Therefore you do not need to retrieve the datatable 'from the session Dim drv As DataRowView = container.DataItem Dim dt As DataTable = drv.Row.Table Dim dc As DataColumn Dim sColumnValue As String Dim sColumnName As String For Each dc In dt.Columns 'you have to add the imagebutton control as a control object to the 'controls collection of the label so that it would be rendered by the 'asp.net engine as a server control Dim btnImg As New ImageButton sColumnName = dc.ColumnName sColumnValue = drv(sColumnName) btnImg.ID = "Expand" + sColumnName btnImg.CommandName = "Select" + sColumnName btnImg.ImageUrl = "images/plus.gif" lbl.Controls.Add(btnImg) 'add the description beside the image button also as a label control 'to the original label's controls collection Dim UrlLabel As New Label UrlLabel.Text = sColumnValue lbl.Controls.Add(UrlLabel) Next End Sub Private Sub DataList1_ItemCommand(ByVal sender As Object, ByVal e As DataListCommandEventArgs) Handles datalist1.ItemCommand 'This is the method that would handle the click event of the dynamically created imagebuttons End Sub Show quoteHide quote "Erik" wrote: > Good Morning, > I am trying to dynamically generate an ImageButton in a datalist label > column. When I have a static reference to the image 'image/plus.gif', the > image is displayed in the label column. > > However, when I try to adapt the html code to be dynamically defined in the > binding of the label column, the image is not displayed. Below is the sub > BindParentLabelColumn where the label text is assigned. > Any insight on the issue is greatly appreciated - I am stumped. > Thank you, Erik > > Public Sub BindParentLabelColumn(ByVal sender As Object, ByVal e As EventArgs) > Dim lbl As Label = CType(sender, Label) > Dim strvals As String > Dim container As DataListItem = CType(lbl.NamingContainer, > DataListItem) > Dim dt As DataTable = Session("DataList_ParentDetailControls") > Dim dc As DataColumn > Dim sColumnValue As String > Dim sColumnName As String > > strvals = "<tr>" > > For Each dc In dt.Columns > sColumnName = dc.ColumnName > sColumnValue = > Convert.ToString(DataBinder.Eval(CType(container, DataListItem).DataItem, > dc.ColumnName)) > > strvals &= "<TD align='center' width='10'><asp:ImageButton > ID='Expand" + sColumnName + "' runat='server' CommandName='Select" + > sColumnName + "' ImageUrl='images/plus.gif'></asp:ImageButton></TD>" & _ > "<TD align='center' width='80'>" + sColumnValue + > "</TD>" > End If > Next > > strvals &= "</tr>" > > lbl.Text = strvals > End Sub 'BindParentLabelColumn Hi Phillip,
Good to hear from you also. I am encountering an error (Object reference not set to an instance of an object.) on line dlstParent1.DataBind after populating the Parent_Data_Table with the SQL string defined from the user's parameter selection. Do I have some redundant code which is causing a conflict? dlstParent1.HeaderTemplate = New DatalistParentLabelColumn(ListItemType.Header) dlstParent1.ItemTemplate = New DatalistParentLabelColumn(ListItemType.Item) Try dvwSelect = New DataView(Parent_Data_Table(sCmd)) If dvwSelect.Table.Rows.Count <> 0 Then dlstParent1.DataSource = dvwSelect dlstParent1.DataBind() Else Session("DataList_ParentDetailControls") = Nothing pnlDetail.Visible = False End If Catch ex As SqlException lblErrorMsg.Text = ex.message.ToString Catch ex As Exception lblErrorMsg.Text = ex.Message.ToString Finally dvwSelect.Dispose() End Try Show quoteHide quote "Phillip Williams" wrote: > Hi Erik, > > Good morning to you too and welcome back to the newsgroup. Regarding your > code: > 1- Server control markup renders into HTML markup when it is processed by > the ASP.NET engine. But when you placed it inside the label text, the label > control will assume that is a regular HTML markup and would not translate it > from being server control markup to HTML > 2- The BindParentLabelColumn would not execute unless you add an event > hanlder to the lable.databinding event. You could have also wrote the logic > within the DataList.ItemDataBound event to achieve the same outcome. > 3- If you want your page to handle the click events of the dynamically > created image buttons you should databind the list during the Page.Init stage. > > Here is how I would modify your code: > > 'starting during the initialization phase of the page's lifecycle > Private Sub Page_Init(ByVal sender As System.Object, ByVal e As > System.EventArgs) Handles MyBase.Init > InitializeComponent() > 'Dynamically created controls should be created during the > 'page initializtion stage for the control to maintain their viewstate > BindControls() > End Sub > > Private Sub BindControls() > 'Explicity cast the session variable to its appropriate type before > using it > datalist1.DataSource = > CType(Session("DataList_ParentDetailControls"), DataTable) > datalist1.DataBind() > > End Sub > > Private Sub DataList1_ItemCreated(ByVal sender As Object, ByVal e As > DataListItemEventArgs) Handles datalist1.ItemCreated > Dim myLabel As Label = e.Item.FindControl("Label1") > 'this step wires up the label databinding event to a method > AddHandler myLabel.DataBinding, AddressOf BindParentLabelColumn > > End Sub > > Public Sub BindParentLabelColumn(ByVal sender As Object, ByVal e As > EventArgs) > Dim lbl As Label = CType(sender, Label) > Dim container As DataListItem = CType(lbl.NamingContainer, > DataListItem) > 'the datalistitem has a pointer to the DataItem (which is datarowview) > 'of your datatable. Therefore you do not need to retrieve the > datatable > 'from the session > Dim drv As DataRowView = container.DataItem > Dim dt As DataTable = drv.Row.Table > Dim dc As DataColumn > Dim sColumnValue As String > Dim sColumnName As String > > > For Each dc In dt.Columns > 'you have to add the imagebutton control as a control object to > the > 'controls collection of the label so that it would be rendered > by the > 'asp.net engine as a server control > Dim btnImg As New ImageButton > sColumnName = dc.ColumnName > sColumnValue = drv(sColumnName) > btnImg.ID = "Expand" + sColumnName > btnImg.CommandName = "Select" + sColumnName > btnImg.ImageUrl = "images/plus.gif" > lbl.Controls.Add(btnImg) > 'add the description beside the image button also as a label > control > 'to the original label's controls collection > Dim UrlLabel As New Label > UrlLabel.Text = sColumnValue > lbl.Controls.Add(UrlLabel) > > Next > > End Sub > Private Sub DataList1_ItemCommand(ByVal sender As Object, ByVal e As > DataListCommandEventArgs) Handles datalist1.ItemCommand > 'This is the method that would handle the click event of the > dynamically created imagebuttons > End Sub > -- > HTH, > Phillip Williams > http://www.societopia.net > http://www.webswapp.com > > > "Erik" wrote: > > > Good Morning, > > I am trying to dynamically generate an ImageButton in a datalist label > > column. When I have a static reference to the image 'image/plus.gif', the > > image is displayed in the label column. > > > > However, when I try to adapt the html code to be dynamically defined in the > > binding of the label column, the image is not displayed. Below is the sub > > BindParentLabelColumn where the label text is assigned. > > Any insight on the issue is greatly appreciated - I am stumped. > > Thank you, Erik > > > > Public Sub BindParentLabelColumn(ByVal sender As Object, ByVal e As EventArgs) > > Dim lbl As Label = CType(sender, Label) > > Dim strvals As String > > Dim container As DataListItem = CType(lbl.NamingContainer, > > DataListItem) > > Dim dt As DataTable = Session("DataList_ParentDetailControls") > > Dim dc As DataColumn > > Dim sColumnValue As String > > Dim sColumnName As String > > > > strvals = "<tr>" > > > > For Each dc In dt.Columns > > sColumnName = dc.ColumnName > > sColumnValue = > > Convert.ToString(DataBinder.Eval(CType(container, DataListItem).DataItem, > > dc.ColumnName)) > > > > strvals &= "<TD align='center' width='10'><asp:ImageButton > > ID='Expand" + sColumnName + "' runat='server' CommandName='Select" + > > sColumnName + "' ImageUrl='images/plus.gif'></asp:ImageButton></TD>" & _ > > "<TD align='center' width='80'>" + sColumnValue + > > "</TD>" > > End If > > Next > > > > strvals &= "</tr>" > > > > lbl.Text = strvals > > End Sub 'BindParentLabelColumn Hi Erik,
Using VS.Net debugger, set up break points within the methods that are triggered upon databinding (of both the datalist and the label) and step through them. Somewhere in the code that you did not post, you will find the line that threw that exception. Show quoteHide quote "Erik" wrote: > Hi Phillip, > Good to hear from you also. > I am encountering an error (Object reference not set to an instance of an > object.) on line dlstParent1.DataBind after populating the Parent_Data_Table > with the SQL string defined from the user's parameter selection. Do I have > some redundant code which is causing a conflict? > > dlstParent1.HeaderTemplate = > New DatalistParentLabelColumn(ListItemType.Header) > dlstParent1.ItemTemplate = > New DatalistParentLabelColumn(ListItemType.Item) > > Try > dvwSelect = New DataView(Parent_Data_Table(sCmd)) > If dvwSelect.Table.Rows.Count <> 0 Then > dlstParent1.DataSource = dvwSelect > dlstParent1.DataBind() > Else > Session("DataList_ParentDetailControls") = Nothing > pnlDetail.Visible = False > End If > Catch ex As SqlException > lblErrorMsg.Text = ex.message.ToString > Catch ex As Exception > lblErrorMsg.Text = ex.Message.ToString > Finally > dvwSelect.Dispose() > End Try > > "Phillip Williams" wrote: > > > Hi Erik, > > > > Good morning to you too and welcome back to the newsgroup. Regarding your > > code: > > 1- Server control markup renders into HTML markup when it is processed by > > the ASP.NET engine. But when you placed it inside the label text, the label > > control will assume that is a regular HTML markup and would not translate it > > from being server control markup to HTML > > 2- The BindParentLabelColumn would not execute unless you add an event > > hanlder to the lable.databinding event. You could have also wrote the logic > > within the DataList.ItemDataBound event to achieve the same outcome. > > 3- If you want your page to handle the click events of the dynamically > > created image buttons you should databind the list during the Page.Init stage. > > > > Here is how I would modify your code: > > > > 'starting during the initialization phase of the page's lifecycle > > Private Sub Page_Init(ByVal sender As System.Object, ByVal e As > > System.EventArgs) Handles MyBase.Init > > InitializeComponent() > > 'Dynamically created controls should be created during the > > 'page initializtion stage for the control to maintain their viewstate > > BindControls() > > End Sub > > > > Private Sub BindControls() > > 'Explicity cast the session variable to its appropriate type before > > using it > > datalist1.DataSource = > > CType(Session("DataList_ParentDetailControls"), DataTable) > > datalist1.DataBind() > > > > End Sub > > > > Private Sub DataList1_ItemCreated(ByVal sender As Object, ByVal e As > > DataListItemEventArgs) Handles datalist1.ItemCreated > > Dim myLabel As Label = e.Item.FindControl("Label1") > > 'this step wires up the label databinding event to a method > > AddHandler myLabel.DataBinding, AddressOf BindParentLabelColumn > > > > End Sub > > > > Public Sub BindParentLabelColumn(ByVal sender As Object, ByVal e As > > EventArgs) > > Dim lbl As Label = CType(sender, Label) > > Dim container As DataListItem = CType(lbl.NamingContainer, > > DataListItem) > > 'the datalistitem has a pointer to the DataItem (which is datarowview) > > 'of your datatable. Therefore you do not need to retrieve the > > datatable > > 'from the session > > Dim drv As DataRowView = container.DataItem > > Dim dt As DataTable = drv.Row.Table > > Dim dc As DataColumn > > Dim sColumnValue As String > > Dim sColumnName As String > > > > > > For Each dc In dt.Columns > > 'you have to add the imagebutton control as a control object to > > the > > 'controls collection of the label so that it would be rendered > > by the > > 'asp.net engine as a server control > > Dim btnImg As New ImageButton > > sColumnName = dc.ColumnName > > sColumnValue = drv(sColumnName) > > btnImg.ID = "Expand" + sColumnName > > btnImg.CommandName = "Select" + sColumnName > > btnImg.ImageUrl = "images/plus.gif" > > lbl.Controls.Add(btnImg) > > 'add the description beside the image button also as a label > > control > > 'to the original label's controls collection > > Dim UrlLabel As New Label > > UrlLabel.Text = sColumnValue > > lbl.Controls.Add(UrlLabel) > > > > Next > > > > End Sub > > Private Sub DataList1_ItemCommand(ByVal sender As Object, ByVal e As > > DataListCommandEventArgs) Handles datalist1.ItemCommand > > 'This is the method that would handle the click event of the > > dynamically created imagebuttons > > End Sub > > -- > > HTH, > > Phillip Williams > > http://www.societopia.net > > http://www.webswapp.com > > > > > > "Erik" wrote: > > > > > Good Morning, > > > I am trying to dynamically generate an ImageButton in a datalist label > > > column. When I have a static reference to the image 'image/plus.gif', the > > > image is displayed in the label column. > > > > > > However, when I try to adapt the html code to be dynamically defined in the > > > binding of the label column, the image is not displayed. Below is the sub > > > BindParentLabelColumn where the label text is assigned. > > > Any insight on the issue is greatly appreciated - I am stumped. > > > Thank you, Erik > > > > > > Public Sub BindParentLabelColumn(ByVal sender As Object, ByVal e As EventArgs) > > > Dim lbl As Label = CType(sender, Label) > > > Dim strvals As String > > > Dim container As DataListItem = CType(lbl.NamingContainer, > > > DataListItem) > > > Dim dt As DataTable = Session("DataList_ParentDetailControls") > > > Dim dc As DataColumn > > > Dim sColumnValue As String > > > Dim sColumnName As String > > > > > > strvals = "<tr>" > > > > > > For Each dc In dt.Columns > > > sColumnName = dc.ColumnName > > > sColumnValue = > > > Convert.ToString(DataBinder.Eval(CType(container, DataListItem).DataItem, > > > dc.ColumnName)) > > > > > > strvals &= "<TD align='center' width='10'><asp:ImageButton > > > ID='Expand" + sColumnName + "' runat='server' CommandName='Select" + > > > sColumnName + "' ImageUrl='images/plus.gif'></asp:ImageButton></TD>" & _ > > > "<TD align='center' width='80'>" + sColumnValue + > > > "</TD>" > > > End If > > > Next > > > > > > strvals &= "</tr>" > > > > > > lbl.Text = strvals > > > End Sub 'BindParentLabelColumn Hi Phillip,
It appears the following is causing the error, with an itemtype = 'header'. Should there be code added to verify the itemtype = 'item'. Thanks, Erik Private Sub dlstParent1_ItemCreated(ByVal sender As Object, ByVal e As DataListItemEventArgs) Handles dlstParent1.ItemCreated Dim myLabel As Label = e.Item.FindControl("Label1") 'this step wires up the label databinding event to a method AddHandler myLabel.DataBinding, AddressOf BindParentLabelColumn End Sub Show quoteHide quote "Phillip Williams" wrote: > Hi Erik, > > Using VS.Net debugger, set up break points within the methods that are > triggered upon databinding (of both the datalist and the label) and step > through them. Somewhere in the code that you did not post, you will find the > line that threw that exception. > -- > HTH, > Phillip Williams > http://www.societopia.net > http://www.webswapp.com > > > "Erik" wrote: > > > Hi Phillip, > > Good to hear from you also. > > I am encountering an error (Object reference not set to an instance of an > > object.) on line dlstParent1.DataBind after populating the Parent_Data_Table > > with the SQL string defined from the user's parameter selection. Do I have > > some redundant code which is causing a conflict? > > > > dlstParent1.HeaderTemplate = > > New DatalistParentLabelColumn(ListItemType.Header) > > dlstParent1.ItemTemplate = > > New DatalistParentLabelColumn(ListItemType.Item) > > > > Try > > dvwSelect = New DataView(Parent_Data_Table(sCmd)) > > If dvwSelect.Table.Rows.Count <> 0 Then > > dlstParent1.DataSource = dvwSelect > > dlstParent1.DataBind() > > Else > > Session("DataList_ParentDetailControls") = Nothing > > pnlDetail.Visible = False > > End If > > Catch ex As SqlException > > lblErrorMsg.Text = ex.message.ToString > > Catch ex As Exception > > lblErrorMsg.Text = ex.Message.ToString > > Finally > > dvwSelect.Dispose() > > End Try > > > > "Phillip Williams" wrote: > > > > > Hi Erik, > > > > > > Good morning to you too and welcome back to the newsgroup. Regarding your > > > code: > > > 1- Server control markup renders into HTML markup when it is processed by > > > the ASP.NET engine. But when you placed it inside the label text, the label > > > control will assume that is a regular HTML markup and would not translate it > > > from being server control markup to HTML > > > 2- The BindParentLabelColumn would not execute unless you add an event > > > hanlder to the lable.databinding event. You could have also wrote the logic > > > within the DataList.ItemDataBound event to achieve the same outcome. > > > 3- If you want your page to handle the click events of the dynamically > > > created image buttons you should databind the list during the Page.Init stage. > > > > > > Here is how I would modify your code: > > > > > > 'starting during the initialization phase of the page's lifecycle > > > Private Sub Page_Init(ByVal sender As System.Object, ByVal e As > > > System.EventArgs) Handles MyBase.Init > > > InitializeComponent() > > > 'Dynamically created controls should be created during the > > > 'page initializtion stage for the control to maintain their viewstate > > > BindControls() > > > End Sub > > > > > > Private Sub BindControls() > > > 'Explicity cast the session variable to its appropriate type before > > > using it > > > datalist1.DataSource = > > > CType(Session("DataList_ParentDetailControls"), DataTable) > > > datalist1.DataBind() > > > > > > End Sub > > > > > > Private Sub DataList1_ItemCreated(ByVal sender As Object, ByVal e As > > > DataListItemEventArgs) Handles datalist1.ItemCreated > > > Dim myLabel As Label = e.Item.FindControl("Label1") > > > 'this step wires up the label databinding event to a method > > > AddHandler myLabel.DataBinding, AddressOf BindParentLabelColumn > > > > > > End Sub > > > > > > Public Sub BindParentLabelColumn(ByVal sender As Object, ByVal e As > > > EventArgs) > > > Dim lbl As Label = CType(sender, Label) > > > Dim container As DataListItem = CType(lbl.NamingContainer, > > > DataListItem) > > > 'the datalistitem has a pointer to the DataItem (which is datarowview) > > > 'of your datatable. Therefore you do not need to retrieve the > > > datatable > > > 'from the session > > > Dim drv As DataRowView = container.DataItem > > > Dim dt As DataTable = drv.Row.Table > > > Dim dc As DataColumn > > > Dim sColumnValue As String > > > Dim sColumnName As String > > > > > > > > > For Each dc In dt.Columns > > > 'you have to add the imagebutton control as a control object to > > > the > > > 'controls collection of the label so that it would be rendered > > > by the > > > 'asp.net engine as a server control > > > Dim btnImg As New ImageButton > > > sColumnName = dc.ColumnName > > > sColumnValue = drv(sColumnName) > > > btnImg.ID = "Expand" + sColumnName > > > btnImg.CommandName = "Select" + sColumnName > > > btnImg.ImageUrl = "images/plus.gif" > > > lbl.Controls.Add(btnImg) > > > 'add the description beside the image button also as a label > > > control > > > 'to the original label's controls collection > > > Dim UrlLabel As New Label > > > UrlLabel.Text = sColumnValue > > > lbl.Controls.Add(UrlLabel) > > > > > > Next > > > > > > End Sub > > > Private Sub DataList1_ItemCommand(ByVal sender As Object, ByVal e As > > > DataListCommandEventArgs) Handles datalist1.ItemCommand > > > 'This is the method that would handle the click event of the > > > dynamically created imagebuttons > > > End Sub > > > -- > > > HTH, > > > Phillip Williams > > > http://www.societopia.net > > > http://www.webswapp.com > > > > > > > > > "Erik" wrote: > > > > > > > Good Morning, > > > > I am trying to dynamically generate an ImageButton in a datalist label > > > > column. When I have a static reference to the image 'image/plus.gif', the > > > > image is displayed in the label column. > > > > > > > > However, when I try to adapt the html code to be dynamically defined in the > > > > binding of the label column, the image is not displayed. Below is the sub > > > > BindParentLabelColumn where the label text is assigned. > > > > Any insight on the issue is greatly appreciated - I am stumped. > > > > Thank you, Erik > > > > > > > > Public Sub BindParentLabelColumn(ByVal sender As Object, ByVal e As EventArgs) > > > > Dim lbl As Label = CType(sender, Label) > > > > Dim strvals As String > > > > Dim container As DataListItem = CType(lbl.NamingContainer, > > > > DataListItem) > > > > Dim dt As DataTable = Session("DataList_ParentDetailControls") > > > > Dim dc As DataColumn > > > > Dim sColumnValue As String > > > > Dim sColumnName As String > > > > > > > > strvals = "<tr>" > > > > > > > > For Each dc In dt.Columns > > > > sColumnName = dc.ColumnName > > > > sColumnValue = > > > > Convert.ToString(DataBinder.Eval(CType(container, DataListItem).DataItem, > > > > dc.ColumnName)) > > > > > > > > strvals &= "<TD align='center' width='10'><asp:ImageButton > > > > ID='Expand" + sColumnName + "' runat='server' CommandName='Select" + > > > > sColumnName + "' ImageUrl='images/plus.gif'></asp:ImageButton></TD>" & _ > > > > "<TD align='center' width='80'>" + sColumnValue + > > > > "</TD>" > > > > End If > > > > Next > > > > > > > > strvals &= "</tr>" > > > > > > > > lbl.Text = strvals > > > > End Sub 'BindParentLabelColumn Hi Erik,
Yes, of course. I exptected you to fill in those tiny details :-) but here is a checked code: Private Sub DataList1_ItemCreated(ByVal sender As Object, ByVal e As DataListItemEventArgs) Handles datalist1.ItemCreated If e.Item.ItemType = ListItemType.Item And e.Item.ItemType = ListItemType.AlternatingItem Then Dim myLabel As Label = e.Item.FindControl("Label1") If Not myLabel Is Nothing Then 'this step wires up the label databinding event to a method AddHandler myLabel.DataBinding, AddressOf BindParentLabelColumn End If End If End Sub Show quoteHide quote "Erik" wrote: > Hi Phillip, > It appears the following is causing the error, with an itemtype = 'header'. > Should there be code added to verify the itemtype = 'item'. Thanks, Erik > > Private Sub dlstParent1_ItemCreated(ByVal sender As Object, ByVal e As > DataListItemEventArgs) Handles dlstParent1.ItemCreated > Dim myLabel As Label = e.Item.FindControl("Label1") > 'this step wires up the label databinding event to a method > AddHandler myLabel.DataBinding, AddressOf BindParentLabelColumn > End Sub > > "Phillip Williams" wrote: > > > Hi Erik, > > > > Using VS.Net debugger, set up break points within the methods that are > > triggered upon databinding (of both the datalist and the label) and step > > through them. Somewhere in the code that you did not post, you will find the > > line that threw that exception. > > -- > > HTH, > > Phillip Williams > > http://www.societopia.net > > http://www.webswapp.com > > > > > > "Erik" wrote: > > > > > Hi Phillip, > > > Good to hear from you also. > > > I am encountering an error (Object reference not set to an instance of an > > > object.) on line dlstParent1.DataBind after populating the Parent_Data_Table > > > with the SQL string defined from the user's parameter selection. Do I have > > > some redundant code which is causing a conflict? > > > > > > dlstParent1.HeaderTemplate = > > > New DatalistParentLabelColumn(ListItemType.Header) > > > dlstParent1.ItemTemplate = > > > New DatalistParentLabelColumn(ListItemType.Item) > > > > > > Try > > > dvwSelect = New DataView(Parent_Data_Table(sCmd)) > > > If dvwSelect.Table.Rows.Count <> 0 Then > > > dlstParent1.DataSource = dvwSelect > > > dlstParent1.DataBind() > > > Else > > > Session("DataList_ParentDetailControls") = Nothing > > > pnlDetail.Visible = False > > > End If > > > Catch ex As SqlException > > > lblErrorMsg.Text = ex.message.ToString > > > Catch ex As Exception > > > lblErrorMsg.Text = ex.Message.ToString > > > Finally > > > dvwSelect.Dispose() > > > End Try > > > > > > "Phillip Williams" wrote: > > > > > > > Hi Erik, > > > > > > > > Good morning to you too and welcome back to the newsgroup. Regarding your > > > > code: > > > > 1- Server control markup renders into HTML markup when it is processed by > > > > the ASP.NET engine. But when you placed it inside the label text, the label > > > > control will assume that is a regular HTML markup and would not translate it > > > > from being server control markup to HTML > > > > 2- The BindParentLabelColumn would not execute unless you add an event > > > > hanlder to the lable.databinding event. You could have also wrote the logic > > > > within the DataList.ItemDataBound event to achieve the same outcome. > > > > 3- If you want your page to handle the click events of the dynamically > > > > created image buttons you should databind the list during the Page.Init stage. > > > > > > > > Here is how I would modify your code: > > > > > > > > 'starting during the initialization phase of the page's lifecycle > > > > Private Sub Page_Init(ByVal sender As System.Object, ByVal e As > > > > System.EventArgs) Handles MyBase.Init > > > > InitializeComponent() > > > > 'Dynamically created controls should be created during the > > > > 'page initializtion stage for the control to maintain their viewstate > > > > BindControls() > > > > End Sub > > > > > > > > Private Sub BindControls() > > > > 'Explicity cast the session variable to its appropriate type before > > > > using it > > > > datalist1.DataSource = > > > > CType(Session("DataList_ParentDetailControls"), DataTable) > > > > datalist1.DataBind() > > > > > > > > End Sub > > > > > > > > Private Sub DataList1_ItemCreated(ByVal sender As Object, ByVal e As > > > > DataListItemEventArgs) Handles datalist1.ItemCreated > > > > Dim myLabel As Label = e.Item.FindControl("Label1") > > > > 'this step wires up the label databinding event to a method > > > > AddHandler myLabel.DataBinding, AddressOf BindParentLabelColumn > > > > > > > > End Sub > > > > > > > > Public Sub BindParentLabelColumn(ByVal sender As Object, ByVal e As > > > > EventArgs) > > > > Dim lbl As Label = CType(sender, Label) > > > > Dim container As DataListItem = CType(lbl.NamingContainer, > > > > DataListItem) > > > > 'the datalistitem has a pointer to the DataItem (which is datarowview) > > > > 'of your datatable. Therefore you do not need to retrieve the > > > > datatable > > > > 'from the session > > > > Dim drv As DataRowView = container.DataItem > > > > Dim dt As DataTable = drv.Row.Table > > > > Dim dc As DataColumn > > > > Dim sColumnValue As String > > > > Dim sColumnName As String > > > > > > > > > > > > For Each dc In dt.Columns > > > > 'you have to add the imagebutton control as a control object to > > > > the > > > > 'controls collection of the label so that it would be rendered > > > > by the > > > > 'asp.net engine as a server control > > > > Dim btnImg As New ImageButton > > > > sColumnName = dc.ColumnName > > > > sColumnValue = drv(sColumnName) > > > > btnImg.ID = "Expand" + sColumnName > > > > btnImg.CommandName = "Select" + sColumnName > > > > btnImg.ImageUrl = "images/plus.gif" > > > > lbl.Controls.Add(btnImg) > > > > 'add the description beside the image button also as a label > > > > control > > > > 'to the original label's controls collection > > > > Dim UrlLabel As New Label > > > > UrlLabel.Text = sColumnValue > > > > lbl.Controls.Add(UrlLabel) > > > > > > > > Next > > > > > > > > End Sub > > > > Private Sub DataList1_ItemCommand(ByVal sender As Object, ByVal e As > > > > DataListCommandEventArgs) Handles datalist1.ItemCommand > > > > 'This is the method that would handle the click event of the > > > > dynamically created imagebuttons > > > > End Sub > > > > -- > > > > HTH, > > > > Phillip Williams > > > > http://www.societopia.net > > > > http://www.webswapp.com > > > > > > > > > > > > "Erik" wrote: > > > > > > > > > Good Morning, > > > > > I am trying to dynamically generate an ImageButton in a datalist label > > > > > column. When I have a static reference to the image 'image/plus.gif', the > > > > > image is displayed in the label column. > > > > > > > > > > However, when I try to adapt the html code to be dynamically defined in the > > > > > binding of the label column, the image is not displayed. Below is the sub > > > > > BindParentLabelColumn where the label text is assigned. > > > > > Any insight on the issue is greatly appreciated - I am stumped. > > > > > Thank you, Erik > > > > > > > > > > Public Sub BindParentLabelColumn(ByVal sender As Object, ByVal e As EventArgs) > > > > > Dim lbl As Label = CType(sender, Label) > > > > > Dim strvals As String > > > > > Dim container As DataListItem = CType(lbl.NamingContainer, > > > > > DataListItem) > > > > > Dim dt As DataTable = Session("DataList_ParentDetailControls") > > > > > Dim dc As DataColumn > > > > > Dim sColumnValue As String > > > > > Dim sColumnName As String > > > > > > > > > > strvals = "<tr>" > > > > > > > > > > For Each dc In dt.Columns > > > > > sColumnName = dc.ColumnName > > > > > sColumnValue = > > > > > Convert.ToString(DataBinder.Eval(CType(container, DataListItem).DataItem, > > > > > dc.ColumnName)) > > > > > > > > > > strvals &= "<TD align='center' width='10'><asp:ImageButton > > > > > ID='Expand" + sColumnName + "' runat='server' CommandName='Select" + > > > > > sColumnName + "' ImageUrl='images/plus.gif'></asp:ImageButton></TD>" & _ > > > > > "<TD align='center' width='80'>" + sColumnValue + > > > > > "</TD>" > > > > > End If > > > > > Next > > > > > > > > > > strvals &= "</tr>" > > > > > > > > > > lbl.Text = strvals > > > > > End Sub 'BindParentLabelColumn Correction; the condition should be:
If e.Item.ItemType = ListItemType.Item Or e.Item.ItemType = ListItemType.AlternatingItem Then '.... End IF Show quoteHide quote "Phillip Williams" wrote: > Hi Erik, > > Yes, of course. I exptected you to fill in those tiny details :-) but here > is a checked code: > > Private Sub DataList1_ItemCreated(ByVal sender As Object, ByVal e As > DataListItemEventArgs) Handles datalist1.ItemCreated > If e.Item.ItemType = ListItemType.Item And e.Item.ItemType = > ListItemType.AlternatingItem Then > Dim myLabel As Label = e.Item.FindControl("Label1") > If Not myLabel Is Nothing Then > 'this step wires up the label databinding event to a method > AddHandler myLabel.DataBinding, AddressOf > BindParentLabelColumn > End If > End If > End Sub > > -- > HTH, > Phillip Williams > http://www.societopia.net > http://www.webswapp.com > > > "Erik" wrote: > > > Hi Phillip, > > It appears the following is causing the error, with an itemtype = 'header'. > > Should there be code added to verify the itemtype = 'item'. Thanks, Erik > > > > Private Sub dlstParent1_ItemCreated(ByVal sender As Object, ByVal e As > > DataListItemEventArgs) Handles dlstParent1.ItemCreated > > Dim myLabel As Label = e.Item.FindControl("Label1") > > 'this step wires up the label databinding event to a method > > AddHandler myLabel.DataBinding, AddressOf BindParentLabelColumn > > End Sub > > > > "Phillip Williams" wrote: > > > > > Hi Erik, > > > > > > Using VS.Net debugger, set up break points within the methods that are > > > triggered upon databinding (of both the datalist and the label) and step > > > through them. Somewhere in the code that you did not post, you will find the > > > line that threw that exception. > > > -- > > > HTH, > > > Phillip Williams > > > http://www.societopia.net > > > http://www.webswapp.com > > > > > > > > > "Erik" wrote: > > > > > > > Hi Phillip, > > > > Good to hear from you also. > > > > I am encountering an error (Object reference not set to an instance of an > > > > object.) on line dlstParent1.DataBind after populating the Parent_Data_Table > > > > with the SQL string defined from the user's parameter selection. Do I have > > > > some redundant code which is causing a conflict? > > > > > > > > dlstParent1.HeaderTemplate = > > > > New DatalistParentLabelColumn(ListItemType.Header) > > > > dlstParent1.ItemTemplate = > > > > New DatalistParentLabelColumn(ListItemType.Item) > > > > > > > > Try > > > > dvwSelect = New DataView(Parent_Data_Table(sCmd)) > > > > If dvwSelect.Table.Rows.Count <> 0 Then > > > > dlstParent1.DataSource = dvwSelect > > > > dlstParent1.DataBind() > > > > Else > > > > Session("DataList_ParentDetailControls") = Nothing > > > > pnlDetail.Visible = False > > > > End If > > > > Catch ex As SqlException > > > > lblErrorMsg.Text = ex.message.ToString > > > > Catch ex As Exception > > > > lblErrorMsg.Text = ex.Message.ToString > > > > Finally > > > > dvwSelect.Dispose() > > > > End Try > > > > > > > > "Phillip Williams" wrote: > > > > > > > > > Hi Erik, > > > > > > > > > > Good morning to you too and welcome back to the newsgroup. Regarding your > > > > > code: > > > > > 1- Server control markup renders into HTML markup when it is processed by > > > > > the ASP.NET engine. But when you placed it inside the label text, the label > > > > > control will assume that is a regular HTML markup and would not translate it > > > > > from being server control markup to HTML > > > > > 2- The BindParentLabelColumn would not execute unless you add an event > > > > > hanlder to the lable.databinding event. You could have also wrote the logic > > > > > within the DataList.ItemDataBound event to achieve the same outcome. > > > > > 3- If you want your page to handle the click events of the dynamically > > > > > created image buttons you should databind the list during the Page.Init stage. > > > > > > > > > > Here is how I would modify your code: > > > > > > > > > > 'starting during the initialization phase of the page's lifecycle > > > > > Private Sub Page_Init(ByVal sender As System.Object, ByVal e As > > > > > System.EventArgs) Handles MyBase.Init > > > > > InitializeComponent() > > > > > 'Dynamically created controls should be created during the > > > > > 'page initializtion stage for the control to maintain their viewstate > > > > > BindControls() > > > > > End Sub > > > > > > > > > > Private Sub BindControls() > > > > > 'Explicity cast the session variable to its appropriate type before > > > > > using it > > > > > datalist1.DataSource = > > > > > CType(Session("DataList_ParentDetailControls"), DataTable) > > > > > datalist1.DataBind() > > > > > > > > > > End Sub > > > > > > > > > > Private Sub DataList1_ItemCreated(ByVal sender As Object, ByVal e As > > > > > DataListItemEventArgs) Handles datalist1.ItemCreated > > > > > Dim myLabel As Label = e.Item.FindControl("Label1") > > > > > 'this step wires up the label databinding event to a method > > > > > AddHandler myLabel.DataBinding, AddressOf BindParentLabelColumn > > > > > > > > > > End Sub > > > > > > > > > > Public Sub BindParentLabelColumn(ByVal sender As Object, ByVal e As > > > > > EventArgs) > > > > > Dim lbl As Label = CType(sender, Label) > > > > > Dim container As DataListItem = CType(lbl.NamingContainer, > > > > > DataListItem) > > > > > 'the datalistitem has a pointer to the DataItem (which is datarowview) > > > > > 'of your datatable. Therefore you do not need to retrieve the > > > > > datatable > > > > > 'from the session > > > > > Dim drv As DataRowView = container.DataItem > > > > > Dim dt As DataTable = drv.Row.Table > > > > > Dim dc As DataColumn > > > > > Dim sColumnValue As String > > > > > Dim sColumnName As String > > > > > > > > > > > > > > > For Each dc In dt.Columns > > > > > 'you have to add the imagebutton control as a control object to > > > > > the > > > > > 'controls collection of the label so that it would be rendered > > > > > by the > > > > > 'asp.net engine as a server control > > > > > Dim btnImg As New ImageButton > > > > > sColumnName = dc.ColumnName > > > > > sColumnValue = drv(sColumnName) > > > > > btnImg.ID = "Expand" + sColumnName > > > > > btnImg.CommandName = "Select" + sColumnName > > > > > btnImg.ImageUrl = "images/plus.gif" > > > > > lbl.Controls.Add(btnImg) > > > > > 'add the description beside the image button also as a label > > > > > control > > > > > 'to the original label's controls collection > > > > > Dim UrlLabel As New Label > > > > > UrlLabel.Text = sColumnValue > > > > > lbl.Controls.Add(UrlLabel) > > > > > > > > > > Next > > > > > > > > > > End Sub > > > > > Private Sub DataList1_ItemCommand(ByVal sender As Object, ByVal e As > > > > > DataListCommandEventArgs) Handles datalist1.ItemCommand > > > > > 'This is the method that would handle the click event of the > > > > > dynamically created imagebuttons > > > > > End Sub > > > > > -- > > > > > HTH, > > > > > Phillip Williams > > > > > http://www.societopia.net > > > > > http://www.webswapp.com > > > > > > > > > > > > > > > "Erik" wrote: > > > > > > > > > > > Good Morning, > > > > > > I am trying to dynamically generate an ImageButton in a datalist label > > > > > > column. When I have a static reference to the image 'image/plus.gif', the > > > > > > image is displayed in the label column. > > > > > > > > > > > > However, when I try to adapt the html code to be dynamically defined in the > > > > > > binding of the label column, the image is not displayed. Below is the sub > > > > > > BindParentLabelColumn where the label text is assigned. > > > > > > Any insight on the issue is greatly appreciated - I am stumped. > > > > > > Thank you, Erik > > > > > > > > > > > > Public Sub BindParentLabelColumn(ByVal sender As Object, ByVal e As EventArgs) > > > > > > Dim lbl As Label = CType(sender, Label) > > > > > > Dim strvals As String > > > > > > Dim container As DataListItem = CType(lbl.NamingContainer, > > > > > > DataListItem) > > > > > > Dim dt As DataTable = Session("DataList_ParentDetailControls") > > > > > > Dim dc As DataColumn > > > > > > Dim sColumnValue As String > > > > > > Dim sColumnName As String > > > > > > > > > > > > strvals = "<tr>" > > > > > > > > > > > > For Each dc In dt.Columns > > > > > > sColumnName = dc.ColumnName > > > > > > sColumnValue = > > > > > > Convert.ToString(DataBinder.Eval(CType(container, DataListItem).DataItem, > > > > > > dc.ColumnName)) > > > > > > > > > > > > strvals &= "<TD align='center' width='10'><asp:ImageButton > > > > > > ID='Expand" + sColumnName + "' runat='server' CommandName='Select" + > > > > > > sColumnName + "' ImageUrl='images/plus.gif'></asp:ImageButton></TD>" & _ > > > > > > "<TD align='center' width='80'>" + sColumnValue + > > > > > > "</TD>" > > > > > > End If > > > > > > Next > > > > > > > > > > > > strvals &= "</tr>" > > > > > > > > > > > > lbl.Text = strvals > > > > > > End Sub 'BindParentLabelColumn Hi Phillip,
The error is still occurring in Dim myLabel As Label = e.Item.FindControl("Label1") AddHandler myLabel.DataBinding, AddressOf BindParentLabelColumn with the addition below. The ID for the item is Nothing. I can't figure out what the control 'Label1' refers to since the controls are being created for the DataList. I apologize for my confusion, but this is new territory for me again. Thanks, Erik Show quoteHide quote "Phillip Williams" wrote: > Correction; the condition should be: > > If e.Item.ItemType = ListItemType.Item Or e.Item.ItemType = > ListItemType.AlternatingItem Then > '.... > End IF > > "Phillip Williams" wrote: > > > Hi Erik, > > > > Yes, of course. I exptected you to fill in those tiny details :-) but here > > is a checked code: > > > > Private Sub DataList1_ItemCreated(ByVal sender As Object, ByVal e As > > DataListItemEventArgs) Handles datalist1.ItemCreated > > If e.Item.ItemType = ListItemType.Item And e.Item.ItemType = > > ListItemType.AlternatingItem Then > > Dim myLabel As Label = e.Item.FindControl("Label1") > > If Not myLabel Is Nothing Then > > 'this step wires up the label databinding event to a method > > AddHandler myLabel.DataBinding, AddressOf > > BindParentLabelColumn > > End If > > End If > > End Sub > > > > -- > > HTH, > > Phillip Williams > > http://www.societopia.net > > http://www.webswapp.com > > > > > > "Erik" wrote: > > > > > Hi Phillip, > > > It appears the following is causing the error, with an itemtype = 'header'. > > > Should there be code added to verify the itemtype = 'item'. Thanks, Erik > > > > > > Private Sub dlstParent1_ItemCreated(ByVal sender As Object, ByVal e As > > > DataListItemEventArgs) Handles dlstParent1.ItemCreated > > > Dim myLabel As Label = e.Item.FindControl("Label1") > > > 'this step wires up the label databinding event to a method > > > AddHandler myLabel.DataBinding, AddressOf BindParentLabelColumn > > > End Sub > > > > > > "Phillip Williams" wrote: > > > > > > > Hi Erik, > > > > > > > > Using VS.Net debugger, set up break points within the methods that are > > > > triggered upon databinding (of both the datalist and the label) and step > > > > through them. Somewhere in the code that you did not post, you will find the > > > > line that threw that exception. > > > > -- > > > > HTH, > > > > Phillip Williams > > > > http://www.societopia.net > > > > http://www.webswapp.com > > > > > > > > > > > > "Erik" wrote: > > > > > > > > > Hi Phillip, > > > > > Good to hear from you also. > > > > > I am encountering an error (Object reference not set to an instance of an > > > > > object.) on line dlstParent1.DataBind after populating the Parent_Data_Table > > > > > with the SQL string defined from the user's parameter selection. Do I have > > > > > some redundant code which is causing a conflict? > > > > > > > > > > dlstParent1.HeaderTemplate = > > > > > New DatalistParentLabelColumn(ListItemType.Header) > > > > > dlstParent1.ItemTemplate = > > > > > New DatalistParentLabelColumn(ListItemType.Item) > > > > > > > > > > Try > > > > > dvwSelect = New DataView(Parent_Data_Table(sCmd)) > > > > > If dvwSelect.Table.Rows.Count <> 0 Then > > > > > dlstParent1.DataSource = dvwSelect > > > > > dlstParent1.DataBind() > > > > > Else > > > > > Session("DataList_ParentDetailControls") = Nothing > > > > > pnlDetail.Visible = False > > > > > End If > > > > > Catch ex As SqlException > > > > > lblErrorMsg.Text = ex.message.ToString > > > > > Catch ex As Exception > > > > > lblErrorMsg.Text = ex.Message.ToString > > > > > Finally > > > > > dvwSelect.Dispose() > > > > > End Try > > > > > > > > > > "Phillip Williams" wrote: > > > > > > > > > > > Hi Erik, > > > > > > > > > > > > Good morning to you too and welcome back to the newsgroup. Regarding your > > > > > > code: > > > > > > 1- Server control markup renders into HTML markup when it is processed by > > > > > > the ASP.NET engine. But when you placed it inside the label text, the label > > > > > > control will assume that is a regular HTML markup and would not translate it > > > > > > from being server control markup to HTML > > > > > > 2- The BindParentLabelColumn would not execute unless you add an event > > > > > > hanlder to the lable.databinding event. You could have also wrote the logic > > > > > > within the DataList.ItemDataBound event to achieve the same outcome. > > > > > > 3- If you want your page to handle the click events of the dynamically > > > > > > created image buttons you should databind the list during the Page.Init stage. > > > > > > > > > > > > Here is how I would modify your code: > > > > > > > > > > > > 'starting during the initialization phase of the page's lifecycle > > > > > > Private Sub Page_Init(ByVal sender As System.Object, ByVal e As > > > > > > System.EventArgs) Handles MyBase.Init > > > > > > InitializeComponent() > > > > > > 'Dynamically created controls should be created during the > > > > > > 'page initializtion stage for the control to maintain their viewstate > > > > > > BindControls() > > > > > > End Sub > > > > > > > > > > > > Private Sub BindControls() > > > > > > 'Explicity cast the session variable to its appropriate type before > > > > > > using it > > > > > > datalist1.DataSource = > > > > > > CType(Session("DataList_ParentDetailControls"), DataTable) > > > > > > datalist1.DataBind() > > > > > > > > > > > > End Sub > > > > > > > > > > > > Private Sub DataList1_ItemCreated(ByVal sender As Object, ByVal e As > > > > > > DataListItemEventArgs) Handles datalist1.ItemCreated > > > > > > Dim myLabel As Label = e.Item.FindControl("Label1") > > > > > > 'this step wires up the label databinding event to a method > > > > > > AddHandler myLabel.DataBinding, AddressOf BindParentLabelColumn > > > > > > > > > > > > End Sub > > > > > > > > > > > > Public Sub BindParentLabelColumn(ByVal sender As Object, ByVal e As > > > > > > EventArgs) > > > > > > Dim lbl As Label = CType(sender, Label) > > > > > > Dim container As DataListItem = CType(lbl.NamingContainer, > > > > > > DataListItem) > > > > > > 'the datalistitem has a pointer to the DataItem (which is datarowview) > > > > > > 'of your datatable. Therefore you do not need to retrieve the > > > > > > datatable > > > > > > 'from the session > > > > > > Dim drv As DataRowView = container.DataItem > > > > > > Dim dt As DataTable = drv.Row.Table > > > > > > Dim dc As DataColumn > > > > > > Dim sColumnValue As String > > > > > > Dim sColumnName As String > > > > > > > > > > > > > > > > > > For Each dc In dt.Columns > > > > > > 'you have to add the imagebutton control as a control object to > > > > > > the > > > > > > 'controls collection of the label so that it would be rendered > > > > > > by the > > > > > > 'asp.net engine as a server control > > > > > > Dim btnImg As New ImageButton > > > > > > sColumnName = dc.ColumnName > > > > > > sColumnValue = drv(sColumnName) > > > > > > btnImg.ID = "Expand" + sColumnName > > > > > > btnImg.CommandName = "Select" + sColumnName > > > > > > btnImg.ImageUrl = "images/plus.gif" > > > > > > lbl.Controls.Add(btnImg) > > > > > > 'add the description beside the image button also as a label > > > > > > control > > > > > > 'to the original label's controls collection > > > > > > Dim UrlLabel As New Label > > > > > > UrlLabel.Text = sColumnValue > > > > > > lbl.Controls.Add(UrlLabel) > > > > > > > > > > > > Next > > > > > > > > > > > > End Sub > > > > > > Private Sub DataList1_ItemCommand(ByVal sender As Object, ByVal e As > > > > > > DataListCommandEventArgs) Handles datalist1.ItemCommand > > > > > > 'This is the method that would handle the click event of the > > > > > > dynamically created imagebuttons > > > > > > End Sub > > > > > > -- > > > > > > HTH, > > > > > > Phillip Williams > > > > > > http://www.societopia.net > > > > > > http://www.webswapp.com > > > > > > > > > > > > > > > > > > "Erik" wrote: > > > > > > > > > > > > > Good Morning, > > > > > > > I am trying to dynamically generate an ImageButton in a datalist label > > > > > > > column. When I have a static reference to the image 'image/plus.gif', the > > > > > > > image is displayed in the label column. > > > > > > > > > > > > > > However, when I try to adapt the html code to be dynamically defined in the > > > > > > > binding of the label column, the image is not displayed. Below is the sub > > > > > > > BindParentLabelColumn where the label text is assigned. > > > > > > > Any insight on the issue is greatly appreciated - I am stumped. > > > > > > > Thank you, Erik > > > > > > > > > > > > > > Public Sub BindParentLabelColumn(ByVal sender As Object, ByVal e As EventArgs) > > > > > > > Dim lbl As Label = CType(sender, Label) > > > > > > > Dim strvals As String > > > > > > > Dim container As DataListItem = CType(lbl.NamingContainer, > > > > > > > DataListItem) > > > > > > > Dim dt As DataTable = Session("DataList_ParentDetailControls") > > > > > > > Dim dc As DataColumn > > > > > > > Dim sColumnValue As String > > > > > > > Dim sColumnName As String > > > > > > > > > > > > > > strvals = "<tr>" > > > > > > > > > > > > > > For Each dc In dt.Columns > > > > > > > sColumnName = dc.ColumnName > > > > > > > sColumnValue = > > > > > > > Convert.ToString(DataBinder.Eval(CType(container, DataListItem).DataItem, > > > > > > > dc.ColumnName)) > > > > > > > > > > > > > > strvals &= "<TD align='center' width='10'><asp:ImageButton > > > > > > > ID='Expand" + sColumnName + "' runat='server' CommandName='Select" + > > > > > > > sColumnName + "' ImageUrl='images/plus.gif'></asp:ImageButton></TD>" & _ > > > > > > > "<TD align='center' width='80'>" + sColumnValue + > > > > > > > "</TD>" > > > > > > > End If > > > > > > > Next > > > > > > > > > > > > > > strvals &= "</tr>" > > > > > > > > > > > > > > lbl.Text = strvals > > > > > > > End Sub 'BindParentLabelColumn Hi Erik,
That's alright. Label1 is the id of the label that I placed within the DataList markup. You have to give the label an Id to be able to identify it using the FindControl method in the Codebehind. <asp:DataList ID="datalist1" Runat='server' > <ItemTemplate> <asp:Label ID="Label1" Runat="server"></asp:Label>" </ItemTemplate> </asp:DataList> Show quoteHide quote "Erik" wrote: > Hi Phillip, > The error is still occurring in > Dim myLabel As Label = e.Item.FindControl("Label1") > AddHandler myLabel.DataBinding, AddressOf BindParentLabelColumn > with the addition below. The ID for the item is Nothing. I can't figure > out what the control 'Label1' refers to since the controls are being created > for the DataList. I apologize for my confusion, but this is new territory > for me again. > Thanks, Erik > > "Phillip Williams" wrote: > > > Correction; the condition should be: > > > > If e.Item.ItemType = ListItemType.Item Or e.Item.ItemType = > > ListItemType.AlternatingItem Then > > '.... > > End IF > > > > "Phillip Williams" wrote: > > > > > Hi Erik, > > > > > > Yes, of course. I exptected you to fill in those tiny details :-) but here > > > is a checked code: > > > > > > Private Sub DataList1_ItemCreated(ByVal sender As Object, ByVal e As > > > DataListItemEventArgs) Handles datalist1.ItemCreated > > > If e.Item.ItemType = ListItemType.Item And e.Item.ItemType = > > > ListItemType.AlternatingItem Then > > > Dim myLabel As Label = e.Item.FindControl("Label1") > > > If Not myLabel Is Nothing Then > > > 'this step wires up the label databinding event to a method > > > AddHandler myLabel.DataBinding, AddressOf > > > BindParentLabelColumn > > > End If > > > End If > > > End Sub > > > > > > -- > > > HTH, > > > Phillip Williams > > > http://www.societopia.net > > > http://www.webswapp.com > > > > > > > > > "Erik" wrote: > > > > > > > Hi Phillip, > > > > It appears the following is causing the error, with an itemtype = 'header'. > > > > Should there be code added to verify the itemtype = 'item'. Thanks, Erik > > > > > > > > Private Sub dlstParent1_ItemCreated(ByVal sender As Object, ByVal e As > > > > DataListItemEventArgs) Handles dlstParent1.ItemCreated > > > > Dim myLabel As Label = e.Item.FindControl("Label1") > > > > 'this step wires up the label databinding event to a method > > > > AddHandler myLabel.DataBinding, AddressOf BindParentLabelColumn > > > > End Sub > > > > > > > > "Phillip Williams" wrote: > > > > > > > > > Hi Erik, > > > > > > > > > > Using VS.Net debugger, set up break points within the methods that are > > > > > triggered upon databinding (of both the datalist and the label) and step > > > > > through them. Somewhere in the code that you did not post, you will find the > > > > > line that threw that exception. > > > > > -- > > > > > HTH, > > > > > Phillip Williams > > > > > http://www.societopia.net > > > > > http://www.webswapp.com > > > > > > > > > > > > > > > "Erik" wrote: > > > > > > > > > > > Hi Phillip, > > > > > > Good to hear from you also. > > > > > > I am encountering an error (Object reference not set to an instance of an > > > > > > object.) on line dlstParent1.DataBind after populating the Parent_Data_Table > > > > > > with the SQL string defined from the user's parameter selection. Do I have > > > > > > some redundant code which is causing a conflict? > > > > > > > > > > > > dlstParent1.HeaderTemplate = > > > > > > New DatalistParentLabelColumn(ListItemType.Header) > > > > > > dlstParent1.ItemTemplate = > > > > > > New DatalistParentLabelColumn(ListItemType.Item) > > > > > > > > > > > > Try > > > > > > dvwSelect = New DataView(Parent_Data_Table(sCmd)) > > > > > > If dvwSelect.Table.Rows.Count <> 0 Then > > > > > > dlstParent1.DataSource = dvwSelect > > > > > > dlstParent1.DataBind() > > > > > > Else > > > > > > Session("DataList_ParentDetailControls") = Nothing > > > > > > pnlDetail.Visible = False > > > > > > End If > > > > > > Catch ex As SqlException > > > > > > lblErrorMsg.Text = ex.message.ToString > > > > > > Catch ex As Exception > > > > > > lblErrorMsg.Text = ex.Message.ToString > > > > > > Finally > > > > > > dvwSelect.Dispose() > > > > > > End Try > > > > > > > > > > > > "Phillip Williams" wrote: > > > > > > > > > > > > > Hi Erik, > > > > > > > > > > > > > > Good morning to you too and welcome back to the newsgroup. Regarding your > > > > > > > code: > > > > > > > 1- Server control markup renders into HTML markup when it is processed by > > > > > > > the ASP.NET engine. But when you placed it inside the label text, the label > > > > > > > control will assume that is a regular HTML markup and would not translate it > > > > > > > from being server control markup to HTML > > > > > > > 2- The BindParentLabelColumn would not execute unless you add an event > > > > > > > hanlder to the lable.databinding event. You could have also wrote the logic > > > > > > > within the DataList.ItemDataBound event to achieve the same outcome. > > > > > > > 3- If you want your page to handle the click events of the dynamically > > > > > > > created image buttons you should databind the list during the Page.Init stage. > > > > > > > > > > > > > > Here is how I would modify your code: > > > > > > > > > > > > > > 'starting during the initialization phase of the page's lifecycle > > > > > > > Private Sub Page_Init(ByVal sender As System.Object, ByVal e As > > > > > > > System.EventArgs) Handles MyBase.Init > > > > > > > InitializeComponent() > > > > > > > 'Dynamically created controls should be created during the > > > > > > > 'page initializtion stage for the control to maintain their viewstate > > > > > > > BindControls() > > > > > > > End Sub > > > > > > > > > > > > > > Private Sub BindControls() > > > > > > > 'Explicity cast the session variable to its appropriate type before > > > > > > > using it > > > > > > > datalist1.DataSource = > > > > > > > CType(Session("DataList_ParentDetailControls"), DataTable) > > > > > > > datalist1.DataBind() > > > > > > > > > > > > > > End Sub > > > > > > > > > > > > > > Private Sub DataList1_ItemCreated(ByVal sender As Object, ByVal e As > > > > > > > DataListItemEventArgs) Handles datalist1.ItemCreated > > > > > > > Dim myLabel As Label = e.Item.FindControl("Label1") > > > > > > > 'this step wires up the label databinding event to a method > > > > > > > AddHandler myLabel.DataBinding, AddressOf BindParentLabelColumn > > > > > > > > > > > > > > End Sub > > > > > > > > > > > > > > Public Sub BindParentLabelColumn(ByVal sender As Object, ByVal e As > > > > > > > EventArgs) > > > > > > > Dim lbl As Label = CType(sender, Label) > > > > > > > Dim container As DataListItem = CType(lbl.NamingContainer, > > > > > > > DataListItem) > > > > > > > 'the datalistitem has a pointer to the DataItem (which is datarowview) > > > > > > > 'of your datatable. Therefore you do not need to retrieve the > > > > > > > datatable > > > > > > > 'from the session > > > > > > > Dim drv As DataRowView = container.DataItem > > > > > > > Dim dt As DataTable = drv.Row.Table > > > > > > > Dim dc As DataColumn > > > > > > > Dim sColumnValue As String > > > > > > > Dim sColumnName As String > > > > > > > > > > > > > > > > > > > > > For Each dc In dt.Columns > > > > > > > 'you have to add the imagebutton control as a control object to > > > > > > > the > > > > > > > 'controls collection of the label so that it would be rendered > > > > > > > by the > > > > > > > 'asp.net engine as a server control > > > > > > > Dim btnImg As New ImageButton > > > > > > > sColumnName = dc.ColumnName > > > > > > > sColumnValue = drv(sColumnName) > > > > > > > btnImg.ID = "Expand" + sColumnName > > > > > > > btnImg.CommandName = "Select" + sColumnName > > > > > > > btnImg.ImageUrl = "images/plus.gif" > > > > > > > lbl.Controls.Add(btnImg) > > > > > > > 'add the description beside the image button also as a label > > > > > > > control > > > > > > > 'to the original label's controls collection > > > > > > > Dim UrlLabel As New Label > > > > > > > UrlLabel.Text = sColumnValue > > > > > > > lbl.Controls.Add(UrlLabel) > > > > > > > > > > > > > > Next > > > > > > > > > > > > > > End Sub > > > > > > > Private Sub DataList1_ItemCommand(ByVal sender As Object, ByVal e As > > > > > > > DataListCommandEventArgs) Handles datalist1.ItemCommand > > > > > > > 'This is the method that would handle the click event of the > > > > > > > dynamically created imagebuttons > > > > > > > End Sub > > > > > > > -- > > > > > > > HTH, > > > > > > > Phillip Williams > > > > > > > http://www.societopia.net > > > > > > > http://www.webswapp.com > > > > > > > > > > > > > > > > > > > > > "Erik" wrote: > > > > > > > > > > > > > > > Good Morning, > > > > > > > > I am trying to dynamically generate an ImageButton in a datalist label > > > > > > > > column. When I have a static reference to the image 'image/plus.gif', the > > > > > > > > image is displayed in the label column. > > > > > > > > > > > > > > > > However, when I try to adapt the html code to be dynamically defined in the > > > > > > > > binding of the label column, the image is not displayed. Below is the sub > > > > > > > > BindParentLabelColumn where the label text is assigned. > > > > > > > > Any insight on the issue is greatly appreciated - I am stumped. > > > > > > > > Thank you, Erik > > > > > > > > > > > > > > > > Public Sub BindParentLabelColumn(ByVal sender As Object, ByVal e As EventArgs) > > > > > > > > Dim lbl As Label = CType(sender, Label) > > > > > > > > Dim strvals As String > > > > > > > > Dim container As DataListItem = CType(lbl.NamingContainer, > > > > > > > > DataListItem) > > > > > > > > Dim dt As DataTable = Session("DataList_ParentDetailControls") > > > > > > > > Dim dc As DataColumn > > > > > > > > Dim sColumnValue As String > > > > > > > > Dim sColumnName As String > > > > > > > > > > > > > > > > strvals = "<tr>" > > > > > > > > > > > > > > > > For Each dc In dt.Columns > > > > > > > > sColumnName = dc.ColumnName > > > > > > > > sColumnValue = > > > > > > > > Convert.ToString(DataBinder.Eval(CType(container, DataListItem).DataItem, > > > > > > > > dc.ColumnName)) > > > > > > > > > > > > > > > > strvals &= "<TD align='center' width='10'><asp:ImageButton > > > > > > > > ID='Expand" + sColumnName + "' runat='server' CommandName='Select" + > > > > > > > > sColumnName + "' ImageUrl='images/plus.gif'></asp:ImageButton></TD>" & _ > > > > > > > > "<TD align='center' width='80'>" + sColumnValue + > > > > > > > > "</TD>" > > > > > > > > End If > > > > > > > > Next > > > > > > > > > > > > > > > > strvals &= "</tr>" > > > > > > > > > > > > > > > > lbl.Text = strvals > > > > > > > > End Sub 'BindParentLabelColumn Is there a way I can define the ItemTemplate labels dynamically in code? The
number and definition of columns displayed is selected by the user. Thanks, Erik Show quoteHide quote "Phillip Williams" wrote: > Hi Erik, > > That's alright. Label1 is the id of the label that I placed within the > DataList markup. You have to give the label an Id to be able to identify it > using the FindControl method in the Codebehind. > > <asp:DataList ID="datalist1" Runat='server' > > <ItemTemplate> > <asp:Label ID="Label1" Runat="server"></asp:Label>" > </ItemTemplate> > </asp:DataList> > > -- > HTH, > Phillip Williams > http://www.societopia.net > http://www.webswapp.com > > > "Erik" wrote: > > > Hi Phillip, > > The error is still occurring in > > Dim myLabel As Label = e.Item.FindControl("Label1") > > AddHandler myLabel.DataBinding, AddressOf BindParentLabelColumn > > with the addition below. The ID for the item is Nothing. I can't figure > > out what the control 'Label1' refers to since the controls are being created > > for the DataList. I apologize for my confusion, but this is new territory > > for me again. > > Thanks, Erik > > > > "Phillip Williams" wrote: > > > > > Correction; the condition should be: > > > > > > If e.Item.ItemType = ListItemType.Item Or e.Item.ItemType = > > > ListItemType.AlternatingItem Then > > > '.... > > > End IF > > > > > > "Phillip Williams" wrote: > > > > > > > Hi Erik, > > > > > > > > Yes, of course. I exptected you to fill in those tiny details :-) but here > > > > is a checked code: > > > > > > > > Private Sub DataList1_ItemCreated(ByVal sender As Object, ByVal e As > > > > DataListItemEventArgs) Handles datalist1.ItemCreated > > > > If e.Item.ItemType = ListItemType.Item And e.Item.ItemType = > > > > ListItemType.AlternatingItem Then > > > > Dim myLabel As Label = e.Item.FindControl("Label1") > > > > If Not myLabel Is Nothing Then > > > > 'this step wires up the label databinding event to a method > > > > AddHandler myLabel.DataBinding, AddressOf > > > > BindParentLabelColumn > > > > End If > > > > End If > > > > End Sub > > > > > > > > -- > > > > HTH, > > > > Phillip Williams > > > > http://www.societopia.net > > > > http://www.webswapp.com > > > > > > > > > > > > "Erik" wrote: > > > > > > > > > Hi Phillip, > > > > > It appears the following is causing the error, with an itemtype = 'header'. > > > > > Should there be code added to verify the itemtype = 'item'. Thanks, Erik > > > > > > > > > > Private Sub dlstParent1_ItemCreated(ByVal sender As Object, ByVal e As > > > > > DataListItemEventArgs) Handles dlstParent1.ItemCreated > > > > > Dim myLabel As Label = e.Item.FindControl("Label1") > > > > > 'this step wires up the label databinding event to a method > > > > > AddHandler myLabel.DataBinding, AddressOf BindParentLabelColumn > > > > > End Sub > > > > > > > > > > "Phillip Williams" wrote: > > > > > > > > > > > Hi Erik, > > > > > > > > > > > > Using VS.Net debugger, set up break points within the methods that are > > > > > > triggered upon databinding (of both the datalist and the label) and step > > > > > > through them. Somewhere in the code that you did not post, you will find the > > > > > > line that threw that exception. > > > > > > -- > > > > > > HTH, > > > > > > Phillip Williams > > > > > > http://www.societopia.net > > > > > > http://www.webswapp.com > > > > > > > > > > > > > > > > > > "Erik" wrote: > > > > > > > > > > > > > Hi Phillip, > > > > > > > Good to hear from you also. > > > > > > > I am encountering an error (Object reference not set to an instance of an > > > > > > > object.) on line dlstParent1.DataBind after populating the Parent_Data_Table > > > > > > > with the SQL string defined from the user's parameter selection. Do I have > > > > > > > some redundant code which is causing a conflict? > > > > > > > > > > > > > > dlstParent1.HeaderTemplate = > > > > > > > New DatalistParentLabelColumn(ListItemType.Header) > > > > > > > dlstParent1.ItemTemplate = > > > > > > > New DatalistParentLabelColumn(ListItemType.Item) > > > > > > > > > > > > > > Try > > > > > > > dvwSelect = New DataView(Parent_Data_Table(sCmd)) > > > > > > > If dvwSelect.Table.Rows.Count <> 0 Then > > > > > > > dlstParent1.DataSource = dvwSelect > > > > > > > dlstParent1.DataBind() > > > > > > > Else > > > > > > > Session("DataList_ParentDetailControls") = Nothing > > > > > > > pnlDetail.Visible = False > > > > > > > End If > > > > > > > Catch ex As SqlException > > > > > > > lblErrorMsg.Text = ex.message.ToString > > > > > > > Catch ex As Exception > > > > > > > lblErrorMsg.Text = ex.Message.ToString > > > > > > > Finally > > > > > > > dvwSelect.Dispose() > > > > > > > End Try > > > > > > > > > > > > > > "Phillip Williams" wrote: > > > > > > > > > > > > > > > Hi Erik, > > > > > > > > > > > > > > > > Good morning to you too and welcome back to the newsgroup. Regarding your > > > > > > > > code: > > > > > > > > 1- Server control markup renders into HTML markup when it is processed by > > > > > > > > the ASP.NET engine. But when you placed it inside the label text, the label > > > > > > > > control will assume that is a regular HTML markup and would not translate it > > > > > > > > from being server control markup to HTML > > > > > > > > 2- The BindParentLabelColumn would not execute unless you add an event > > > > > > > > hanlder to the lable.databinding event. You could have also wrote the logic > > > > > > > > within the DataList.ItemDataBound event to achieve the same outcome. > > > > > > > > 3- If you want your page to handle the click events of the dynamically > > > > > > > > created image buttons you should databind the list during the Page.Init stage. > > > > > > > > > > > > > > > > Here is how I would modify your code: > > > > > > > > > > > > > > > > 'starting during the initialization phase of the page's lifecycle > > > > > > > > Private Sub Page_Init(ByVal sender As System.Object, ByVal e As > > > > > > > > System.EventArgs) Handles MyBase.Init > > > > > > > > InitializeComponent() > > > > > > > > 'Dynamically created controls should be created during the > > > > > > > > 'page initializtion stage for the control to maintain their viewstate > > > > > > > > BindControls() > > > > > > > > End Sub > > > > > > > > > > > > > > > > Private Sub BindControls() > > > > > > > > 'Explicity cast the session variable to its appropriate type before > > > > > > > > using it > > > > > > > > datalist1.DataSource = > > > > > > > > CType(Session("DataList_ParentDetailControls"), DataTable) > > > > > > > > datalist1.DataBind() > > > > > > > > > > > > > > > > End Sub > > > > > > > > > > > > > > > > Private Sub DataList1_ItemCreated(ByVal sender As Object, ByVal e As > > > > > > > > DataListItemEventArgs) Handles datalist1.ItemCreated > > > > > > > > Dim myLabel As Label = e.Item.FindControl("Label1") > > > > > > > > 'this step wires up the label databinding event to a method > > > > > > > > AddHandler myLabel.DataBinding, AddressOf BindParentLabelColumn > > > > > > > > > > > > > > > > End Sub > > > > > > > > > > > > > > > > Public Sub BindParentLabelColumn(ByVal sender As Object, ByVal e As > > > > > > > > EventArgs) > > > > > > > > Dim lbl As Label = CType(sender, Label) > > > > > > > > Dim container As DataListItem = CType(lbl.NamingContainer, > > > > > > > > DataListItem) > > > > > > > > 'the datalistitem has a pointer to the DataItem (which is datarowview) > > > > > > > > 'of your datatable. Therefore you do not need to retrieve the > > > > > > > > datatable > > > > > > > > 'from the session > > > > > > > > Dim drv As DataRowView = container.DataItem > > > > > > > > Dim dt As DataTable = drv.Row.Table > > > > > > > > Dim dc As DataColumn > > > > > > > > Dim sColumnValue As String > > > > > > > > Dim sColumnName As String > > > > > > > > > > > > > > > > > > > > > > > > For Each dc In dt.Columns > > > > > > > > 'you have to add the imagebutton control as a control object to > > > > > > > > the > > > > > > > > 'controls collection of the label so that it would be rendered > > > > > > > > by the > > > > > > > > 'asp.net engine as a server control > > > > > > > > Dim btnImg As New ImageButton > > > > > > > > sColumnName = dc.ColumnName > > > > > > > > sColumnValue = drv(sColumnName) > > > > > > > > btnImg.ID = "Expand" + sColumnName > > > > > > > > btnImg.CommandName = "Select" + sColumnName > > > > > > > > btnImg.ImageUrl = "images/plus.gif" > > > > > > > > lbl.Controls.Add(btnImg) > > > > > > > > 'add the description beside the image button also as a label > > > > > > > > control > > > > > > > > 'to the original label's controls collection > > > > > > > > Dim UrlLabel As New Label > > > > > > > > UrlLabel.Text = sColumnValue > > > > > > > > lbl.Controls.Add(UrlLabel) > > > > > > > > > > > > > > > > Next > > > > > > > > > > > > > > > > End Sub > > > > > > > > Private Sub DataList1_ItemCommand(ByVal sender As Object, ByVal e As > > > > > > > > DataListCommandEventArgs) Handles datalist1.ItemCommand > > > > > > > > 'This is the method that would handle the click event of the > > > > > > > > dynamically created imagebuttons > > > > > > > > End Sub > > > > > > > > -- > > > > > > > > HTH, > > > > > > > > Phillip Williams > > > > > > > > http://www.societopia.net > > > > > > > > http://www.webswapp.com > > > > > > > > > > > > > > > > > > > > > > > > "Erik" wrote: > > > > > > > > > > > > > > > > > Good Morning, > > > > > > > > > I am trying to dynamically generate an ImageButton in a datalist label > > > > > > > > > column. When I have a static reference to the image 'image/plus.gif', the > > > > > > > > > image is displayed in the label column. > > > > > > > > > > > > > > > > > > However, when I try to adapt the html code to be dynamically defined in the > > > > > > > > > binding of the label column, the image is not displayed. Below is the sub > > > > > > > > > BindParentLabelColumn where the label text is assigned. > > > > > > > > > Any insight on the issue is greatly appreciated - I am stumped. > > > > > > > > > Thank you, Erik > > > > > > > > > > > > > > > > > > Public Sub BindParentLabelColumn(ByVal sender As Object, ByVal e As EventArgs) > > > > > > > > > Dim lbl As Label = CType(sender, Label) > > > > > > > > > Dim strvals As String > > > > > > > > > Dim container As DataListItem = CType(lbl.NamingContainer, > > > > > > > > > DataListItem) > > > > > > > > > Dim dt As DataTable = Session("DataList_ParentDetailControls") > > > > > > > > > Dim dc As DataColumn > > > > > > > > > Dim sColumnValue As String > > > > > > > > > Dim sColumnName As String > > > > > > > > > > > > > > > > > > strvals = "<tr>" > > > > > > > > > > > > > > > > > > For Each dc In dt.Columns > > > > > > > > > sColumnName = dc.ColumnName > > > > > > > > > sColumnValue = > > > > > > > > > Convert.ToString(DataBinder.Eval(CType(container, DataListItem).DataItem, > > > > > > > > > dc.ColumnName)) > > > > > > > > > > > > > > > > > > strvals &= "<TD align='center' width='10'><asp:ImageButton > > > > > > > > > ID='Expand" + sColumnName + "' runat='server' CommandName='Select" + > > > > > > > > > sColumnName + "' ImageUrl='images/plus.gif'></asp:ImageButton></TD>" & _ > > > > > > > > > "<TD align='center' width='80'>" + sColumnValue + > > > > > > > > > "</TD>" > > > > > > > > > End If > > > > > > > > > Next > > > > > > > > > > > > > > > > > > strvals &= "</tr>" > > > > > > > > > > > > > > > > > > lbl.Text = strvals > > > > > > > > > End Sub 'BindParentLabelColumn Hi Erik,
We have just displayed any number of controls (instead of HTML table columns) into one label (which is inside one ItemTemplate). This was just a modification to your original code to explain to you the concept of building the controls dynamically. (Instead of concatenating markup text that you started with, you now learned that you could add the controls dynamically within the page initialization stage to maintain their functions) To reach to a full production outcome of the application that you desire, you can build on the concepts of adding dynamic controls that we achieved in this code by refining the way you place the controls. For example, instead of using one label you can build a Table within the DataListItem. You can start by trying a simple markup like this: <asp:DataList ID="datalist1" Runat='server' CssClass="Container"> <ItemTemplate> <%--leave it empty to be populated programmatically based on # of columns--%> </ItemTemplate> </asp:DataList> And then move the code where you created the buttons within the stage of processing the DataList.ItemDataBound event like this: Private Sub DataList1_ItemDataBound(ByVal sender As Object, ByVal e As DataListItemEventArgs) Handles datalist1.ItemDataBound Dim drv As DataRowView = e.Item.DataItem() Dim dt As DataTable = drv.Row.Table Dim dc As DataColumn Dim sColumnValue As String Dim sColumnName As String 'each row would be formatted as a table that contains one row and as many cells as there 'are columns on the datatable Dim t As New Table e.Item.Controls.Add(t) 'add the table to the datalist row Dim r As New TableRow t.Rows.Add(r) For Each dc In dt.Columns Dim c As New TableCell r.Cells.Add(c) 'you have to add the imagebutton control as a control object to the 'controls collection of the label so that it would be rendered by the 'asp.net engine as a server control Dim btnImg As New ImageButton sColumnName = dc.ColumnName sColumnValue = drv(sColumnName) btnImg.ID = "Expand" + sColumnName btnImg.CommandName = "Select" + sColumnName btnImg.ImageUrl = "images/plus.gif" c.Controls.Add(btnImg) 'add the description beside the image button also as a label control 'to the original label's controls collection Dim UrlLabel As New Label UrlLabel.Text = sColumnValue c.Controls.Add(UrlLabel) Next End Sub Once you get the hang of this you might try a one-more step complex approach: to dynamically create the ItemTemplates as in this sample: http://msdn.microsoft.com/library/default.asp?url=/library/en-us/vbcon/html/vbtskcreatingwebservercontroltemplatesdynamically.asp If you still cannot get it to work, let me know and I might put a demo of it on my website. Show quoteHide quote "Erik" wrote: > Is there a way I can define the ItemTemplate labels dynamically in code? The > number and definition of columns displayed is selected by the user. > Thanks, Erik > "Phillip Williams" wrote: > > > Hi Erik, > > > > That's alright. Label1 is the id of the label that I placed within the > > DataList markup. You have to give the label an Id to be able to identify it > > using the FindControl method in the Codebehind. > > > > <asp:DataList ID="datalist1" Runat='server' > > > <ItemTemplate> > > <asp:Label ID="Label1" Runat="server"></asp:Label>" > > </ItemTemplate> > > </asp:DataList> > > > > -- > > HTH, > > Phillip Williams > > http://www.societopia.net > > http://www.webswapp.com > > > > > > "Erik" wrote: > > > > > Hi Phillip, > > > The error is still occurring in > > > Dim myLabel As Label = e.Item.FindControl("Label1") > > > AddHandler myLabel.DataBinding, AddressOf BindParentLabelColumn > > > with the addition below. The ID for the item is Nothing. I can't figure > > > out what the control 'Label1' refers to since the controls are being created > > > for the DataList. I apologize for my confusion, but this is new territory > > > for me again. > > > Thanks, Erik > > > > > > "Phillip Williams" wrote: > > > > > > > Correction; the condition should be: > > > > > > > > If e.Item.ItemType = ListItemType.Item Or e.Item.ItemType = > > > > ListItemType.AlternatingItem Then > > > > '.... > > > > End IF > > > > > > > > "Phillip Williams" wrote: > > > > > > > > > Hi Erik, > > > > > > > > > > Yes, of course. I exptected you to fill in those tiny details :-) but here > > > > > is a checked code: > > > > > > > > > > Private Sub DataList1_ItemCreated(ByVal sender As Object, ByVal e As > > > > > DataListItemEventArgs) Handles datalist1.ItemCreated > > > > > If e.Item.ItemType = ListItemType.Item And e.Item.ItemType = > > > > > ListItemType.AlternatingItem Then > > > > > Dim myLabel As Label = e.Item.FindControl("Label1") > > > > > If Not myLabel Is Nothing Then > > > > > 'this step wires up the label databinding event to a method > > > > > AddHandler myLabel.DataBinding, AddressOf > > > > > BindParentLabelColumn > > > > > End If > > > > > End If > > > > > End Sub > > > > > > > > > > -- > > > > > HTH, > > > > > Phillip Williams > > > > > http://www.societopia.net > > > > > http://www.webswapp.com > > > > > > > > > > > > > > > "Erik" wrote: > > > > > > > > > > > Hi Phillip, > > > > > > It appears the following is causing the error, with an itemtype = 'header'. > > > > > > Should there be code added to verify the itemtype = 'item'. Thanks, Erik > > > > > > > > > > > > Private Sub dlstParent1_ItemCreated(ByVal sender As Object, ByVal e As > > > > > > DataListItemEventArgs) Handles dlstParent1.ItemCreated > > > > > > Dim myLabel As Label = e.Item.FindControl("Label1") > > > > > > 'this step wires up the label databinding event to a method > > > > > > AddHandler myLabel.DataBinding, AddressOf BindParentLabelColumn > > > > > > End Sub > > > > > > > > > > > > "Phillip Williams" wrote: > > > > > > > > > > > > > Hi Erik, > > > > > > > > > > > > > > Using VS.Net debugger, set up break points within the methods that are > > > > > > > triggered upon databinding (of both the datalist and the label) and step > > > > > > > through them. Somewhere in the code that you did not post, you will find the > > > > > > > line that threw that exception. > > > > > > > -- > > > > > > > HTH, > > > > > > > Phillip Williams > > > > > > > http://www.societopia.net > > > > > > > http://www.webswapp.com > > > > > > > > > > > > > > > > > > > > > "Erik" wrote: > > > > > > > > > > > > > > > Hi Phillip, > > > > > > > > Good to hear from you also. > > > > > > > > I am encountering an error (Object reference not set to an instance of an > > > > > > > > object.) on line dlstParent1.DataBind after populating the Parent_Data_Table > > > > > > > > with the SQL string defined from the user's parameter selection. Do I have > > > > > > > > some redundant code which is causing a conflict? > > > > > > > > > > > > > > > > dlstParent1.HeaderTemplate = > > > > > > > > New DatalistParentLabelColumn(ListItemType.Header) > > > > > > > > dlstParent1.ItemTemplate = > > > > > > > > New DatalistParentLabelColumn(ListItemType.Item) > > > > > > > > > > > > > > > > Try > > > > > > > > dvwSelect = New DataView(Parent_Data_Table(sCmd)) > > > > > > > > If dvwSelect.Table.Rows.Count <> 0 Then > > > > > > > > dlstParent1.DataSource = dvwSelect > > > > > > > > dlstParent1.DataBind() > > > > > > > > Else > > > > > > > > Session("DataList_ParentDetailControls") = Nothing > > > > > > > > pnlDetail.Visible = False > > > > > > > > End If > > > > > > > > Catch ex As SqlException > > > > > > > > lblErrorMsg.Text = ex.message.ToString > > > > > > > > Catch ex As Exception > > > > > > > > lblErrorMsg.Text = ex.Message.ToString > > > > > > > > Finally > > > > > > > > dvwSelect.Dispose() > > > > > > > > End Try > > > > > > > > > > > > > > > > "Phillip Williams" wrote: > > > > > > > > > > > > > > > > > Hi Erik, > > > > > > > > > > > > > > > > > > Good morning to you too and welcome back to the newsgroup. Regarding your > > > > > > > > > code: > > > > > > > > > 1- Server control markup renders into HTML markup when it is processed by > > > > > > > > > the ASP.NET engine. But when you placed it inside the label text, the label > > > > > > > > > control will assume that is a regular HTML markup and would not translate it > > > > > > > > > from being server control markup to HTML > > > > > > > > > 2- The BindParentLabelColumn would not execute unless you add an event > > > > > > > > > hanlder to the lable.databinding event. You could have also wrote the logic > > > > > > > > > within the DataList.ItemDataBound event to achieve the same outcome. > > > > > > > > > 3- If you want your page to handle the click events of the dynamically > > > > > > > > > created image buttons you should databind the list during the Page.Init stage. > > > > > > > > > > > > > > > > > > Here is how I would modify your code: > > > > > > > > > > > > > > > > > > 'starting during the initialization phase of the page's lifecycle > > > > > > > > > Private Sub Page_Init(ByVal sender As System.Object, ByVal e As > > > > > > > > > System.EventArgs) Handles MyBase.Init > > > > > > > > > InitializeComponent() > > > > > > > > > 'Dynamically created controls should be created during the > > > > > > > > > 'page initializtion stage for the control to maintain their viewstate > > > > > > > > > BindControls() > > > > > > > > > End Sub > > > > > > > > > > > > > > > > > > Private Sub BindControls() > > > > > > > > > 'Explicity cast the session variable to its appropriate type before > > > > > > > > > using it > > > > > > > > > datalist1.DataSource = > > > > > > > > > CType(Session("DataList_ParentDetailControls"), DataTable) > > > > > > > > > datalist1.DataBind() > > > > > > > > > > > > > > > > > > End Sub > > > > > > > > > > > > > > > > > > Private Sub DataList1_ItemCreated(ByVal sender As Object, ByVal e As > > > > > > > > > DataListItemEventArgs) Handles datalist1.ItemCreated > > > > > > > > > Dim myLabel As Label = e.Item.FindControl("Label1") > > > > > > > > > 'this step wires up the label databinding event to a method > > > > > > > > > AddHandler myLabel.DataBinding, AddressOf BindParentLabelColumn > > > > > > > > > > > > > > > > > > End Sub > > > > > > > > > > > > > > > > > > Public Sub BindParentLabelColumn(ByVal sender As Object, ByVal e As > > > > > > > > > EventArgs) > > > > > > > > > Dim lbl As Label = CType(sender, Label) > > > > > > > > > Dim container As DataListItem = CType(lbl.NamingContainer, > > > > > > > > > DataListItem) > > > > > > > > > 'the datalistitem has a pointer to the DataItem (which is datarowview) > > > > > > > > > 'of your datatable. Therefore you do not need to retrieve the > > > > > > > > > datatable > > > > > > > > > 'from the session > > > > > > > > > Dim drv As DataRowView = container.DataItem > > > > > > > > > Dim dt As DataTable = drv.Row.Table > > > > > > > > > Dim dc As DataColumn > > > > > > > > > Dim sColumnValue As String > > > > > > > > > Dim sColumnName As String > > > > > > > > > > > > > > > > > > > > > > > > > > > For Each dc In dt.Columns > > > > > > > > > 'you have to add the imagebutton control as a control object to > > > > > > > > > the > > > > > > > > > 'controls collection of the label so that it would be rendered > > > > > > > > > by the > > > > > > > > > 'asp.net engine as a server control > > > > > > > > > Dim btnImg As New ImageButton > > > > > > > > > sColumnName = dc.ColumnName > > > > > > > > > sColumnValue = drv(sColumnName) > > > > > > > > > btnImg.ID = "Expand" + sColumnName > > > > > > > > > btnImg.CommandName = "Select" + sColumnName > > > > > > > > > btnImg.ImageUrl = "images/plus.gif" > > > > > > > > > lbl.Controls.Add(btnImg) > > > > > > > > > 'add the description beside the image button also as a label > > > > > > > > > control > > > > > > > > > 'to the original label's controls collection > > > > > > > > > Dim UrlLabel As New Label > > > > > > > > > UrlLabel.Text = sColumnValue > > > > > > > > > lbl.Controls.Add(UrlLabel) > > > > > > > > > > > > > > > > > > Next > > > > > > > > > > > > > > > > > > End Sub > > > > > > > > > Private Sub DataList1_ItemCommand(ByVal sender As Object, ByVal e As > > > > > > > > > DataListCommandEventArgs) Handles datalist1.ItemCommand > > > > > > > > > 'This is the method that would handle the click event of the > > > > > > > > > dynamically created imagebuttons > > > > > > > > > End Sub > > > > > > > > > -- > > > > > > > > > HTH, > > > > > > > > > Phillip Williams > > > > > > > > > http://www.societopia.net > > > > > > > > > http://www.webswapp.com > > > > > > > > > > > > > > > > > > > > > > > > > > > "Erik" wrote: > > > > > > > > > > > > > > > > > > > Good Morning, > > > > > > > > > > I am trying to dynamically generate an ImageButton in a datalist label > > > > > > > > > > column. When I have a static reference to the image 'image/plus.gif', the > > > > > > > > > > image is displayed in the label column. > > > > > > > > > > > > > > > > > > > > However, when I try to adapt the html code to be dynamically defined in the > > > > > > > > > > binding of the label column, the image is not displayed. Below is the sub > > > > > > > > > > BindParentLabelColumn where the label text is assigned. > > > > > > > > > > Any insight on the issue is greatly appreciated - I am stumped. > > > > > > > > > > Thank you, Erik > > > > > > > > > > > > > > > > > > > > Public Sub BindParentLabelColumn(ByVal sender As Object, ByVal e As EventArgs) > > > > > > > > > > Dim lbl As Label = CType(sender, Label) > > > > > > > > > > Dim strvals As String > > > > > > > > > > Dim container As DataListItem = CType(lbl.NamingContainer, > > > > > > > > > > DataListItem) > > > > > > > > > > Dim dt As DataTable = Session("DataList_ParentDetailControls") > > > > > > > > > > Dim dc As DataColumn > > > > > > > > > > Dim sColumnValue As String > > > > > > > > > > Dim sColumnName As String > > > > > > > > > > > > > > > > > > > > strvals = "<tr>" > > > > > > > > > > > > > > > > > > > > For Each dc In dt.Columns > > > > > > > > > > sColumnName = dc.ColumnName > > > > > > > > > > sColumnValue = > > > > > > > > > > Convert.ToString(DataBinder.Eval(CType(container, DataListItem).DataItem, > > > > > > > > > > dc.ColumnName)) > > > > > > > > > > > > > > > > > > > > strvals &= "<TD align='center' width='10'><asp:ImageButton > > > > > > > > > > ID='Expand" + sColumnName + "' runat='server' CommandName='Select" + > > > > > > > > > > sColumnName + "' ImageUrl='images/plus.gif'></asp:ImageButton></TD>" & _ > > > > > > > > > > "<TD align='center' width='80'>" + sColumnValue + > > > > > > > > > > "</TD>" > > > > > > > > > > End If > > > > > > > > > > Next > > > > > > > > > > > > > > > > > > > > strvals &= "</tr>" > > > > > > > > > > > > > > > > > > > > lbl.Text = strvals > > > > > > > > > > End Sub 'BindParentLabelColumn I managed to put a concept demo that combines the techniques we referred to
below: 1) creating templates dynamically, and 2) creating controls dynamically, based on an undetermined number of columns in a datatable. I used here the datagrid instead of the datalist. http://www.societopia.net/Samples/DataGrid_DynamicallyCreatedColumns.aspx Show quoteHide quote "Phillip Williams" wrote: > Hi Erik, > > We have just displayed any number of controls (instead of HTML table > columns) into one label (which is inside one ItemTemplate). > > This was just a modification to your original code to explain to you the > concept of building the controls dynamically. (Instead of concatenating > markup text that you started with, you now learned that you could add the > controls dynamically within the page initialization stage to maintain their > functions) > > To reach to a full production outcome of the application that you desire, > you can build on the concepts of adding dynamic controls that we achieved in > this code by refining the way you place the controls. > > For example, instead of using one label you can build a Table within the > DataListItem. You can start by trying a simple markup like this: > > <asp:DataList ID="datalist1" Runat='server' CssClass="Container"> > <ItemTemplate> > <%--leave it empty to be populated programmatically based on # of > columns--%> > </ItemTemplate> > </asp:DataList> > > And then move the code where you created the buttons within the stage of > processing the DataList.ItemDataBound event like this: > > Private Sub DataList1_ItemDataBound(ByVal sender As Object, ByVal e As > DataListItemEventArgs) Handles datalist1.ItemDataBound > Dim drv As DataRowView = e.Item.DataItem() > Dim dt As DataTable = drv.Row.Table > Dim dc As DataColumn > Dim sColumnValue As String > Dim sColumnName As String > 'each row would be formatted as a table that contains one row and as > many cells as there > 'are columns on the datatable > Dim t As New Table > e.Item.Controls.Add(t) 'add the table to the datalist row > Dim r As New TableRow > t.Rows.Add(r) > > For Each dc In dt.Columns > Dim c As New TableCell > r.Cells.Add(c) > 'you have to add the imagebutton control as a control object to > the > 'controls collection of the label so that it would be rendered > by the > 'asp.net engine as a server control > Dim btnImg As New ImageButton > sColumnName = dc.ColumnName > sColumnValue = drv(sColumnName) > btnImg.ID = "Expand" + sColumnName > btnImg.CommandName = "Select" + sColumnName > btnImg.ImageUrl = "images/plus.gif" > c.Controls.Add(btnImg) > 'add the description beside the image button also as a label > control > 'to the original label's controls collection > Dim UrlLabel As New Label > UrlLabel.Text = sColumnValue > c.Controls.Add(UrlLabel) > Next > > End Sub > > Once you get the hang of this you might try a one-more step complex > approach: to dynamically create the ItemTemplates as in this sample: > http://msdn.microsoft.com/library/default.asp?url=/library/en-us/vbcon/html/vbtskcreatingwebservercontroltemplatesdynamically.asp > > If you still cannot get it to work, let me know and I might put a demo of it > on my website. > -- > HTH, > Phillip Williams > http://www.societopia.net > http://www.webswapp.com > > > "Erik" wrote: > > > Is there a way I can define the ItemTemplate labels dynamically in code? The > > number and definition of columns displayed is selected by the user. > > Thanks, Erik > > "Phillip Williams" wrote: > > > > > Hi Erik, > > > > > > That's alright. Label1 is the id of the label that I placed within the > > > DataList markup. You have to give the label an Id to be able to identify it > > > using the FindControl method in the Codebehind. > > > > > > <asp:DataList ID="datalist1" Runat='server' > > > > <ItemTemplate> > > > <asp:Label ID="Label1" Runat="server"></asp:Label>" > > > </ItemTemplate> > > > </asp:DataList> > > > > > > -- > > > HTH, > > > Phillip Williams > > > http://www.societopia.net > > > http://www.webswapp.com > > > > > > > > > "Erik" wrote: > > > > > > > Hi Phillip, > > > > The error is still occurring in > > > > Dim myLabel As Label = e.Item.FindControl("Label1") > > > > AddHandler myLabel.DataBinding, AddressOf BindParentLabelColumn > > > > with the addition below. The ID for the item is Nothing. I can't figure > > > > out what the control 'Label1' refers to since the controls are being created > > > > for the DataList. I apologize for my confusion, but this is new territory > > > > for me again. > > > > Thanks, Erik > > > > > > > > "Phillip Williams" wrote: > > > > > > > > > Correction; the condition should be: > > > > > > > > > > If e.Item.ItemType = ListItemType.Item Or e.Item.ItemType = > > > > > ListItemType.AlternatingItem Then > > > > > '.... > > > > > End IF > > > > > > > > > > "Phillip Williams" wrote: > > > > > > > > > > > Hi Erik, > > > > > > > > > > > > Yes, of course. I exptected you to fill in those tiny details :-) but here > > > > > > is a checked code: > > > > > > > > > > > > Private Sub DataList1_ItemCreated(ByVal sender As Object, ByVal e As > > > > > > DataListItemEventArgs) Handles datalist1.ItemCreated > > > > > > If e.Item.ItemType = ListItemType.Item And e.Item.ItemType = > > > > > > ListItemType.AlternatingItem Then > > > > > > Dim myLabel As Label = e.Item.FindControl("Label1") > > > > > > If Not myLabel Is Nothing Then > > > > > > 'this step wires up the label databinding event to a method > > > > > > AddHandler myLabel.DataBinding, AddressOf > > > > > > BindParentLabelColumn > > > > > > End If > > > > > > End If > > > > > > End Sub > > > > > > > > > > > > -- > > > > > > HTH, > > > > > > Phillip Williams > > > > > > http://www.societopia.net > > > > > > http://www.webswapp.com > > > > > > > > > > > > > > > > > > "Erik" wrote: > > > > > > > > > > > > > Hi Phillip, > > > > > > > It appears the following is causing the error, with an itemtype = 'header'. > > > > > > > Should there be code added to verify the itemtype = 'item'. Thanks, Erik > > > > > > > > > > > > > > Private Sub dlstParent1_ItemCreated(ByVal sender As Object, ByVal e As > > > > > > > DataListItemEventArgs) Handles dlstParent1.ItemCreated > > > > > > > Dim myLabel As Label = e.Item.FindControl("Label1") > > > > > > > 'this step wires up the label databinding event to a method > > > > > > > AddHandler myLabel.DataBinding, AddressOf BindParentLabelColumn > > > > > > > End Sub > > > > > > > > > > > > > > "Phillip Williams" wrote: > > > > > > > > > > > > > > > Hi Erik, > > > > > > > > > > > > > > > > Using VS.Net debugger, set up break points within the methods that are > > > > > > > > triggered upon databinding (of both the datalist and the label) and step > > > > > > > > through them. Somewhere in the code that you did not post, you will find the > > > > > > > > line that threw that exception. > > > > > > > > -- > > > > > > > > HTH, > > > > > > > > Phillip Williams > > > > > > > > http://www.societopia.net > > > > > > > > http://www.webswapp.com > > > > > > > > > > > > > > > > > > > > > > > > "Erik" wrote: > > > > > > > > > > > > > > > > > Hi Phillip, > > > > > > > > > Good to hear from you also. > > > > > > > > > I am encountering an error (Object reference not set to an instance of an > > > > > > > > > object.) on line dlstParent1.DataBind after populating the Parent_Data_Table > > > > > > > > > with the SQL string defined from the user's parameter selection. Do I have > > > > > > > > > some redundant code which is causing a conflict? > > > > > > > > > > > > > > > > > > dlstParent1.HeaderTemplate = > > > > > > > > > New DatalistParentLabelColumn(ListItemType.Header) > > > > > > > > > dlstParent1.ItemTemplate = > > > > > > > > > New DatalistParentLabelColumn(ListItemType.Item) > > > > > > > > > > > > > > > > > > Try > > > > > > > > > dvwSelect = New DataView(Parent_Data_Table(sCmd)) > > > > > > > > > If dvwSelect.Table.Rows.Count <> 0 Then > > > > > > > > > dlstParent1.DataSource = dvwSelect > > > > > > > > > dlstParent1.DataBind() > > > > > > > > > Else > > > > > > > > > Session("DataList_ParentDetailControls") = Nothing > > > > > > > > > pnlDetail.Visible = False > > > > > > > > > End If > > > > > > > > > Catch ex As SqlException > > > > > > > > > lblErrorMsg.Text = ex.message.ToString > > > > > > > > > Catch ex As Exception > > > > > > > > > lblErrorMsg.Text = ex.Message.ToString > > > > > > > > > Finally > > > > > > > > > dvwSelect.Dispose() > > > > > > > > > End Try > > > > > > > > > > > > > > > > > > "Phillip Williams" wrote: > > > > > > > > > > > > > > > > > > > Hi Erik, > > > > > > > > > > > > > > > > > > > > Good morning to you too and welcome back to the newsgroup. Regarding your > > > > > > > > > > code: > > > > > > > > > > 1- Server control markup renders into HTML markup when it is processed by > > > > > > > > > > the ASP.NET engine. But when you placed it inside the label text, the label > > > > > > > > > > control will assume that is a regular HTML markup and would not translate it > > > > > > > > > > from being server control markup to HTML > > > > > > > > > > 2- The BindParentLabelColumn would not execute unless you add an event > > > > > > > > > > hanlder to the lable.databinding event. You could have also wrote the logic > > > > > > > > > > within the DataList.ItemDataBound event to achieve the same outcome. > > > > > > > > > > 3- If you want your page to handle the click events of the dynamically > > > > > > > > > > created image buttons you should databind the list during the Page.Init stage. > > > > > > > > > > > > > > > > > > > > Here is how I would modify your code: > > > > > > > > > > > > > > > > > > > > 'starting during the initialization phase of the page's lifecycle > > > > > > > > > > Private Sub Page_Init(ByVal sender As System.Object, ByVal e As > > > > > > > > > > System.EventArgs) Handles MyBase.Init > > > > > > > > > > InitializeComponent() > > > > > > > > > > 'Dynamically created controls should be created during the > > > > > > > > > > 'page initializtion stage for the control to maintain their viewstate > > > > > > > > > > BindControls() > > > > > > > > > > End Sub > > > > > > > > > > > > > > > > > > > > Private Sub BindControls() > > > > > > > > > > 'Explicity cast the session variable to its appropriate type before > > > > > > > > > > using it > > > > > > > > > > datalist1.DataSource = > > > > > > > > > > CType(Session("DataList_ParentDetailControls"), DataTable) > > > > > > > > > > datalist1.DataBind() > > > > > > > > > > > > > > > > > > > > End Sub > > > > > > > > > > > > > > > > > > > > Private Sub DataList1_ItemCreated(ByVal sender As Object, ByVal e As > > > > > > > > > > DataListItemEventArgs) Handles datalist1.ItemCreated > > > > > > > > > > Dim myLabel As Label = e.Item.FindControl("Label1") > > > > > > > > > > 'this step wires up the label databinding event to a method > > > > > > > > > > AddHandler myLabel.DataBinding, AddressOf BindParentLabelColumn > > > > > > > > > > > > > > > > > > > > End Sub > > > > > > > > > > > > > > > > > > > > Public Sub BindParentLabelColumn(ByVal sender As Object, ByVal e As > > > > > > > > > > EventArgs) > > > > > > > > > > Dim lbl As Label = CType(sender, Label) > > > > > > > > > > Dim container As DataListItem = CType(lbl.NamingContainer, > > > > > > > > > > DataListItem) > > > > > > > > > > 'the datalistitem has a pointer to the DataItem (which is datarowview) > > > > > > > > > > 'of your datatable. Therefore you do not need to retrieve the > > > > > > > > > > datatable > > > > > > > > > > 'from the session > > > > > > > > > > Dim drv As DataRowView = container.DataItem > > > > > > > > > > Dim dt As DataTable = drv.Row.Table > > > > > > > > > > Dim dc As DataColumn > > > > > > > > > > Dim sColumnValue As String > > > > > > > > > > Dim sColumnName As String > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > For Each dc In dt.Columns > > > > > > > > > > 'you have to add the imagebutton control as a control object to > > > > > > > > > > the > > > > > > > > > > 'controls collection of the label so that it would be rendered > > > > > > > > > > by the > > > > > > > > > > 'asp.net engine as a server control > > > > > > > > > > Dim btnImg As New ImageButton > > > > > > > > > > sColumnName = dc.ColumnName > > > > > > > > > > sColumnValue = drv(sColumnName) > > > > > > > > > > btnImg.ID = "Expand" + sColumnName > > > > > > > > > > btnImg.CommandName = "Select" + sColumnName > > > > > > > > > > btnImg.ImageUrl = "images/plus.gif" > > > > > > > > > > lbl.Controls.Add(btnImg) > > > > > > > > > > 'add the description beside the image button also as a label > > > > > > > > > > control > > > > > > > > > > 'to the original label's controls collection > > > > > > > > > > Dim UrlLabel As New Label > > > > > > > > > > UrlLabel.Text = sColumnValue > > > > > > > > > > lbl.Controls.Add(UrlLabel) > > > > > > > > > > > > > > > > > > > > Next > > > > > > > > > > > > > > > > > > > > End Sub > > > > > > > > > > Private Sub DataList1_ItemCommand(ByVal sender As Object, ByVal e As > > > > > > > > > > DataListCommandEventArgs) Handles datalist1.ItemCommand > > > > > > > > > > 'This is the method that would handle the click event of the Good Morning Phillip,
Thanks you for the instruction. I have been working through the code, and can't figure out an exception I am getting on line Dim drv As DataRowView = e.Item.DataItem() in dlstParent1_ItemDataBound. e is Nothing. Thanks, Erik Show quoteHide quote "Phillip Williams" wrote: > I managed to put a concept demo that combines the techniques we referred to > below: 1) creating templates dynamically, and 2) creating controls > dynamically, based on an undetermined number of columns in a datatable. I > used here the datagrid instead of the datalist. > > http://www.societopia.net/Samples/DataGrid_DynamicallyCreatedColumns.aspx > > -- > HTH, > Phillip Williams > http://www.societopia.net > http://www.webswapp.com > > > "Phillip Williams" wrote: > > > Hi Erik, > > > > We have just displayed any number of controls (instead of HTML table > > columns) into one label (which is inside one ItemTemplate). > > > > This was just a modification to your original code to explain to you the > > concept of building the controls dynamically. (Instead of concatenating > > markup text that you started with, you now learned that you could add the > > controls dynamically within the page initialization stage to maintain their > > functions) > > > > To reach to a full production outcome of the application that you desire, > > you can build on the concepts of adding dynamic controls that we achieved in > > this code by refining the way you place the controls. > > > > For example, instead of using one label you can build a Table within the > > DataListItem. You can start by trying a simple markup like this: > > > > <asp:DataList ID="datalist1" Runat='server' CssClass="Container"> > > <ItemTemplate> > > <%--leave it empty to be populated programmatically based on # of > > columns--%> > > </ItemTemplate> > > </asp:DataList> > > > > And then move the code where you created the buttons within the stage of > > processing the DataList.ItemDataBound event like this: > > > > Private Sub DataList1_ItemDataBound(ByVal sender As Object, ByVal e As > > DataListItemEventArgs) Handles datalist1.ItemDataBound > > Dim drv As DataRowView = e.Item.DataItem() > > Dim dt As DataTable = drv.Row.Table > > Dim dc As DataColumn > > Dim sColumnValue As String > > Dim sColumnName As String > > 'each row would be formatted as a table that contains one row and as > > many cells as there > > 'are columns on the datatable > > Dim t As New Table > > e.Item.Controls.Add(t) 'add the table to the datalist row > > Dim r As New TableRow > > t.Rows.Add(r) > > > > For Each dc In dt.Columns > > Dim c As New TableCell > > r.Cells.Add(c) > > 'you have to add the imagebutton control as a control object to > > the > > 'controls collection of the label so that it would be rendered > > by the > > 'asp.net engine as a server control > > Dim btnImg As New ImageButton > > sColumnName = dc.ColumnName > > sColumnValue = drv(sColumnName) > > btnImg.ID = "Expand" + sColumnName > > btnImg.CommandName = "Select" + sColumnName > > btnImg.ImageUrl = "images/plus.gif" > > c.Controls.Add(btnImg) > > 'add the description beside the image button also as a label > > control > > 'to the original label's controls collection > > Dim UrlLabel As New Label > > UrlLabel.Text = sColumnValue > > c.Controls.Add(UrlLabel) > > Next > > > > End Sub > > > > Once you get the hang of this you might try a one-more step complex > > approach: to dynamically create the ItemTemplates as in this sample: > > http://msdn.microsoft.com/library/default.asp?url=/library/en-us/vbcon/html/vbtskcreatingwebservercontroltemplatesdynamically.asp > > > > If you still cannot get it to work, let me know and I might put a demo of it > > on my website. > > -- > > HTH, > > Phillip Williams > > http://www.societopia.net > > http://www.webswapp.com > > > > > > "Erik" wrote: > > > > > Is there a way I can define the ItemTemplate labels dynamically in code? The > > > number and definition of columns displayed is selected by the user. > > > Thanks, Erik > > > "Phillip Williams" wrote: > > > > > > > Hi Erik, > > > > > > > > That's alright. Label1 is the id of the label that I placed within the > > > > DataList markup. You have to give the label an Id to be able to identify it > > > > using the FindControl method in the Codebehind. > > > > > > > > <asp:DataList ID="datalist1" Runat='server' > > > > > <ItemTemplate> > > > > <asp:Label ID="Label1" Runat="server"></asp:Label>" > > > > </ItemTemplate> > > > > </asp:DataList> > > > > > > > > -- > > > > HTH, > > > > Phillip Williams > > > > http://www.societopia.net > > > > http://www.webswapp.com > > > > > > > > > > > > "Erik" wrote: > > > > > > > > > Hi Phillip, > > > > > The error is still occurring in > > > > > Dim myLabel As Label = e.Item.FindControl("Label1") > > > > > AddHandler myLabel.DataBinding, AddressOf BindParentLabelColumn > > > > > with the addition below. The ID for the item is Nothing. I can't figure > > > > > out what the control 'Label1' refers to since the controls are being created > > > > > for the DataList. I apologize for my confusion, but this is new territory > > > > > for me again. > > > > > Thanks, Erik > > > > > > > > > > "Phillip Williams" wrote: > > > > > > > > > > > Correction; the condition should be: > > > > > > > > > > > > If e.Item.ItemType = ListItemType.Item Or e.Item.ItemType = > > > > > > ListItemType.AlternatingItem Then > > > > > > '.... > > > > > > End IF > > > > > > > > > > > > "Phillip Williams" wrote: > > > > > > > > > > > > > Hi Erik, > > > > > > > > > > > > > > Yes, of course. I exptected you to fill in those tiny details :-) but here > > > > > > > is a checked code: > > > > > > > > > > > > > > Private Sub DataList1_ItemCreated(ByVal sender As Object, ByVal e As > > > > > > > DataListItemEventArgs) Handles datalist1.ItemCreated > > > > > > > If e.Item.ItemType = ListItemType.Item And e.Item.ItemType = > > > > > > > ListItemType.AlternatingItem Then > > > > > > > Dim myLabel As Label = e.Item.FindControl("Label1") > > > > > > > If Not myLabel Is Nothing Then > > > > > > > 'this step wires up the label databinding event to a method > > > > > > > AddHandler myLabel.DataBinding, AddressOf > > > > > > > BindParentLabelColumn > > > > > > > End If > > > > > > > End If > > > > > > > End Sub > > > > > > > > > > > > > > -- > > > > > > > HTH, > > > > > > > Phillip Williams > > > > > > > http://www.societopia.net > > > > > > > http://www.webswapp.com > > > > > > > > > > > > > > > > > > > > > "Erik" wrote: > > > > > > > > > > > > > > > Hi Phillip, > > > > > > > > It appears the following is causing the error, with an itemtype = 'header'. > > > > > > > > Should there be code added to verify the itemtype = 'item'. Thanks, Erik > > > > > > > > > > > > > > > > Private Sub dlstParent1_ItemCreated(ByVal sender As Object, ByVal e As > > > > > > > > DataListItemEventArgs) Handles dlstParent1.ItemCreated > > > > > > > > Dim myLabel As Label = e.Item.FindControl("Label1") > > > > > > > > 'this step wires up the label databinding event to a method > > > > > > > > AddHandler myLabel.DataBinding, AddressOf BindParentLabelColumn > > > > > > > > End Sub > > > > > > > > > > > > > > > > "Phillip Williams" wrote: > > > > > > > > > > > > > > > > > Hi Erik, > > > > > > > > > > > > > > > > > > Using VS.Net debugger, set up break points within the methods that are > > > > > > > > > triggered upon databinding (of both the datalist and the label) and step > > > > > > > > > through them. Somewhere in the code that you did not post, you will find the > > > > > > > > > line that threw that exception. > > > > > > > > > -- > > > > > > > > > HTH, > > > > > > > > > Phillip Williams > > > > > > > > > http://www.societopia.net > > > > > > > > > http://www.webswapp.com > > > > > > > > > > > > > > > > > > > > > > > > > > > "Erik" wrote: > > > > > > > > > > > > > > > > > > > Hi Phillip, > > > > > > > > > > Good to hear from you also. > > > > > > > > > > I am encountering an error (Object reference not set to an instance of an > > > > > > > > > > object.) on line dlstParent1.DataBind after populating the Parent_Data_Table > > > > > > > > > > with the SQL string defined from the user's parameter selection. Do I have > > > > > > > > > > some redundant code which is causing a conflict? > > > > > > > > > > > > > > > > > > > > dlstParent1.HeaderTemplate = > > > > > > > > > > New DatalistParentLabelColumn(ListItemType.Header) > > > > > > > > > > dlstParent1.ItemTemplate = > > > > > > > > > > New DatalistParentLabelColumn(ListItemType.Item) > > > > > > > > > > > > > > > > > > > > Try > > > > > > > > > > dvwSelect = New DataView(Parent_Data_Table(sCmd)) > > > > > > > > > > If dvwSelect.Table.Rows.Count <> 0 Then > > > > > > > > > > dlstParent1.DataSource = dvwSelect > > > > > > > > > > dlstParent1.DataBind() > > > > > > > > > > Else > > > > > > > > > > Session("DataList_ParentDetailControls") = Nothing > > > > > > > > > > pnlDetail.Visible = False > > > > > > > > > > End If > > > > > > > > > > Catch ex As SqlException > > > > > > > > > > lblErrorMsg.Text = ex.message.ToString > > > > > > > > > > Catch ex As Exception > > > > > > > > > > lblErrorMsg.Text = ex.Message.ToString > > > > > > > > > > Finally > > > > > > > > > > dvwSelect.Dispose() > > > > > > > > > > End Try > > > > > > > > > > > > > > > > > > > > "Phillip Williams" wrote: > > > > > > > > > > > > > > > > > > > > > Hi Erik, > > > > > > > > > > > > > > > > > > > > > > Good morning to you too and welcome back to the newsgroup. Regarding your > > > > > > > > > > > code: > > > > > > > > > > > 1- Server control markup renders into HTML markup when it is processed by > > > > > > > > > > > the ASP.NET engine. But when you placed it inside the label text, the label > > > > > > > > > > > control will assume that is a regular HTML markup and would not translate it > > > > > > > > > > > from being server control markup to HTML > > > > > > > > > > > 2- The BindParentLabelColumn would not execute unless you add an event > > > > > > > > > > > hanlder to the lable.databinding event. You could have also wrote the logic > > > > > > > > > > > within the DataList.ItemDataBound event to achieve the same outcome. > > > > > > > > > > > 3- If you want your page to handle the click events of the dynamically > > > > > > > > > > > created image buttons you should databind the list during the Page.Init stage. > > > > > > > > > > > > > > > > > > > > > > Here is how I would modify your code: > > > > > > > > > > > > > > > > > > > > > > 'starting during the initialization phase of the page's lifecycle > > > > > > > > > > > Private Sub Page_Init(ByVal sender As System.Object, ByVal e As > > > > > > > > > > > System.EventArgs) Handles MyBase.Init > > > > > > > > > > > InitializeComponent() > > > > > > > > > > > 'Dynamically created controls should be created during the > > > > > > > > > > > 'page initializtion stage for the control to maintain their viewstate > > > > > > > > > > > BindControls() > > > > > > > > > > > End Sub > > > > > > > > > > > > > > > > > > > > > > Private Sub BindControls() > > > > > > > > > > > 'Explicity cast the session variable to its appropriate type before > > > > > > > > > > > using it > > > > > > > > > > > datalist1.DataSource = > > > > > > > > > > > CType(Session("DataList_ParentDetailControls"), DataTable) > > > > > > > > > > > datalist1.DataBind() > > > > > > > > > > > > > > > > > > > > > > End Sub > > > > > > > > > > > > > > > > > > > > > > Private Sub DataList1_ItemCreated(ByVal sender As Object, ByVal e As > > > > > > > > > > > DataListItemEventArgs) Handles datalist1.ItemCreated > > > > > > > > > > > Dim myLabel As Label = e.Item.FindControl("Label1") > > > > > > > > > > > 'this step wires up the label databinding event to a method > > > > > > > > > > > AddHandler myLabel.DataBinding, AddressOf BindParentLabelColumn > > > > > > > > > > > > > > > > > > > > > > End Sub > > > > > > > > > > > > > > > > > > > > > > Public Sub BindParentLabelColumn(ByVal sender As Object, ByVal e As > > > > > > > > > > > EventArgs) > > > > > > > > > > > Dim lbl As Label = CType(sender, Label) > > > > > > > > > > > Dim container As DataListItem = CType(lbl.NamingContainer, > > > > > > > > > > > DataListItem) > > > > > > > > > > > 'the datalistitem has a pointer to the DataItem (which is datarowview) > > > > > > > > > > > 'of your datatable. Therefore you do not need to retrieve the > > > > > > > > > > > datatable > > > > > > > > > > > 'from the session > > > > > > > > > > > Dim drv As DataRowView = container.DataItem > > > > > > > > > > > Dim dt As DataTable = drv.Row.Table > > > > > > > > > > > Dim dc As DataColumn > > > > > > > > > > > Dim sColumnValue As String > > > > > > > > > > > Dim sColumnName As String > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > For Each dc In dt.Columns > > > > > > > > > > > 'you have to add the imagebutton control as a control object to > > > > > > > > > > > the > > > > > > > > > > > 'controls collection of the label so that it would be rendered > > > > > > > > > > > by the > > > > > > > > > > > 'asp.net engine as a server control > > > > > > > > > > > Dim btnImg As New ImageButton > > > > > > > > > > > sColumnName = dc.ColumnName > > > > > > > > > > > sColumnValue = drv(sColumnName) > > > > > > > > > > > btnImg.ID = "Expand" + sColumnName Hi Erik,
Can you post the code. (I know this page is getting pretty long, so you might want to chop off the history out of it) Also, have you looked at the demo using the datagrid that I posted. It might prove easier in getting a tidy layout. Show quoteHide quote "Erik" wrote: > Good Morning Phillip, > Thanks you for the instruction. I have been working through the code, and > can't figure out an exception I am getting on line Dim drv As DataRowView = > e.Item.DataItem() in dlstParent1_ItemDataBound. e is Nothing. > Thanks, Erik > "Phillip Williams" wrote: > > > I managed to put a concept demo that combines the techniques we referred to > > below: 1) creating templates dynamically, and 2) creating controls > > dynamically, based on an undetermined number of columns in a datatable. I > > used here the datagrid instead of the datalist. > > > > http://www.societopia.net/Samples/DataGrid_DynamicallyCreatedColumns.aspx > > > > -- > > HTH, > > Phillip Williams > > http://www.societopia.net > > http://www.webswapp.com > > > > > > "Phillip Williams" wrote: > > > > > Hi Erik, > > > > > > We have just displayed any number of controls (instead of HTML table > > > columns) into one label (which is inside one ItemTemplate). > > > > > > This was just a modification to your original code to explain to you the > > > concept of building the controls dynamically. (Instead of concatenating > > > markup text that you started with, you now learned that you could add the > > > controls dynamically within the page initialization stage to maintain their > > > functions) > > > > > > To reach to a full production outcome of the application that you desire, > > > you can build on the concepts of adding dynamic controls that we achieved in > > > this code by refining the way you place the controls. > > > > > > For example, instead of using one label you can build a Table within the > > > DataListItem. You can start by trying a simple markup like this: > > > > > > <asp:DataList ID="datalist1" Runat='server' CssClass="Container"> > > > <ItemTemplate> > > > <%--leave it empty to be populated programmatically based on # of > > > columns--%> > > > </ItemTemplate> > > > </asp:DataList> > > > > > > And then move the code where you created the buttons within the stage of > > > processing the DataList.ItemDataBound event like this: > > > > > > Private Sub DataList1_ItemDataBound(ByVal sender As Object, ByVal e As > > > DataListItemEventArgs) Handles datalist1.ItemDataBound > > > Dim drv As DataRowView = e.Item.DataItem() > > > Dim dt As DataTable = drv.Row.Table > > > Dim dc As DataColumn > > > Dim sColumnValue As String > > > Dim sColumnName As String > > > 'each row would be formatted as a table that contains one row and as > > > many cells as there > > > 'are columns on the datatable > > > Dim t As New Table > > > e.Item.Controls.Add(t) 'add the table to the datalist row > > > Dim r As New TableRow > > > t.Rows.Add(r) > > > > > > For Each dc In dt.Columns > > > Dim c As New TableCell > > > r.Cells.Add(c) > > > 'you have to add the imagebutton control as a control object to > > > the > > > 'controls collection of the label so that it would be rendered > > > by the > > > 'asp.net engine as a server control > > > Dim btnImg As New ImageButton > > > sColumnName = dc.ColumnName > > > sColumnValue = drv(sColumnName) > > > btnImg.ID = "Expand" + sColumnName > > > btnImg.CommandName = "Select" + sColumnName > > > btnImg.ImageUrl = "images/plus.gif" > > > c.Controls.Add(btnImg) > > > 'add the description beside the image button also as a label > > > control > > > 'to the original label's controls collection > > > Dim UrlLabel As New Label > > > UrlLabel.Text = sColumnValue > > > c.Controls.Add(UrlLabel) > > > Next > > > > > > End Sub > > > > > > Once you get the hang of this you might try a one-more step complex > > > approach: to dynamically create the ItemTemplates as in this sample: > > > http://msdn.microsoft.com/library/default.asp?url=/library/en-us/vbcon/html/vbtskcreatingwebservercontroltemplatesdynamically.asp > > > > > > If you still cannot get it to work, let me know and I might put a demo of it > > > on my website. > > > -- > > > HTH, > > > Phillip Williams > > > http://www.societopia.net > > > http://www.webswapp.com > > > > > > > > > "Erik" wrote: > > > > > > > Is there a way I can define the ItemTemplate labels dynamically in code? The > > > > number and definition of columns displayed is selected by the user. > > > > Thanks, Erik > > > > "Phillip Williams" wrote: > > > > > > > > > Hi Erik, > > > > > > > > > > That's alright. Label1 is the id of the label that I placed within the > > > > > DataList markup. You have to give the label an Id to be able to identify it > > > > > using the FindControl method in the Codebehind. > > > > > > > > > > <asp:DataList ID="datalist1" Runat='server' > > > > > > <ItemTemplate> > > > > > <asp:Label ID="Label1" Runat="server"></asp:Label>" > > > > > </ItemTemplate> > > > > > </asp:DataList> > > > > > > > > > > -- > > > > > HTH, > > > > > Phillip Williams > > > > > http://www.societopia.net > > > > > http://www.webswapp.com > > > > > > > > > > > > > > > "Erik" wrote: > > > > > > > > > > > Hi Phillip, > > > > > > The error is still occurring in > > > > > > Dim myLabel As Label = e.Item.FindControl("Label1") > > > > > > AddHandler myLabel.DataBinding, AddressOf BindParentLabelColumn > > > > > > with the addition below. The ID for the item is Nothing. I can't figure > > > > > > out what the control 'Label1' refers to since the controls are being created > > > > > > for the DataList. I apologize for my confusion, but this is new territory > > > > > > for me again. > > > > > > Thanks, Erik > > > > > > > > > > > > "Phillip Williams" wrote: > > > > > > > > > > > > > Correction; the condition should be: > > > > > > > > > > > > > > If e.Item.ItemType = ListItemType.Item Or e.Item.ItemType = > > > > > > > ListItemType.AlternatingItem Then > > > > > > > '.... > > > > > > > End IF > > > > > > > > > > > > > > "Phillip Williams" wrote: > > > > > > > > > > > > > > > Hi Erik, > > > > > > > > > > > > > > > > Yes, of course. I exptected you to fill in those tiny details :-) but here > > > > > > > > is a checked code: > > > > > > > > > > > > > > > > Private Sub DataList1_ItemCreated(ByVal sender As Object, ByVal e As > > > > > > > > DataListItemEventArgs) Handles datalist1.ItemCreated > > > > > > > > If e.Item.ItemType = ListItemType.Item And e.Item.ItemType = > > > > > > > > ListItemType.AlternatingItem Then > > > > > > > > Dim myLabel As Label = e.Item.FindControl("Label1") > > > > > > > > If Not myLabel Is Nothing Then > > > > > > > > 'this step wires up the label databinding event to a method > > > > > > > > AddHandler myLabel.DataBinding, AddressOf > > > > > > > > BindParentLabelColumn > > > > > > > > End If > > > > > > > > End If > > > > > > > > End Sub > > > > > > > > > > > > > > > > -- > > > > > > > > HTH, > > > > > > > > Phillip Williams > > > > > > > > http://www.societopia.net > > > > > > > > http://www.webswapp.com > > > > > > > > > > > > > > > > > > > > > > > > "Erik" wrote: > > > > > > > > > > > > > > > > > Hi Phillip, > > > > > > > > > It appears the following is causing the error, with an itemtype = 'header'. > > > > > > > > > Should there be code added to verify the itemtype = 'item'. Thanks, Erik > > > > > > > > > > > > > > > > > > Private Sub dlstParent1_ItemCreated(ByVal sender As Object, ByVal e As > > > > > > > > > DataListItemEventArgs) Handles dlstParent1.ItemCreated > > > > > > > > > Dim myLabel As Label = e.Item.FindControl("Label1") > > > > > > > > > 'this step wires up the label databinding event to a method > > > > > > > > > AddHandler myLabel.DataBinding, AddressOf BindParentLabelColumn > > > > > > > > > End Sub > > > > > > > > > > > > > > > > > > "Phillip Williams" wrote: > > > > > > > > > > > > > > > > > > > Hi Erik, > > > > > > > > > > > > > > > > > > > > Using VS.Net debugger, set up break points within the methods that are > > > > > > > > > > triggered upon databinding (of both the datalist and the label) and step > > > > > > > > > > through them. Somewhere in the code that you did not post, you will find the > > > > > > > > > > line that threw that exception. > > > > > > > > > > -- > > > > > > > > > > HTH, > > > > > > > > > > Phillip Williams > > > > > > > > > > http://www.societopia.net > > > > > > > > > > http://www.webswapp.com > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > "Erik" wrote: > > > > > > > > > > > > > > > > > > > > > Hi Phillip, > > > > > > > > > > > Good to hear from you also. > > > > > > > > > > > I am encountering an error (Object reference not set to an instance of an > > > > > > > > > > > object.) on line dlstParent1.DataBind after populating the Parent_Data_Table > > > > > > > > > > > with the SQL string defined from the user's parameter selection. Do I have > > > > > > > > > > > some redundant code which is causing a conflict? > > > > > > > > > > > > > > > > > > > > > > dlstParent1.HeaderTemplate = > > > > > > > > > > > New DatalistParentLabelColumn(ListItemType.Header) > > > > > > > > > > > dlstParent1.ItemTemplate = > > > > > > > > > > > New DatalistParentLabelColumn(ListItemType.Item) > > > > > > > > > > > > > > > > > > > > > > Try > > > > > > > > > > > dvwSelect = New DataView(Parent_Data_Table(sCmd)) > > > > > > > > > > > If dvwSelect.Table.Rows.Count <> 0 Then > > > > > > > > > > > dlstParent1.DataSource = dvwSelect > > > > > > > > > > > dlstParent1.DataBind() > > > > > > > > > > > Else > > > > > > > > > > > Session("DataList_ParentDetailControls") = Nothing > > > > > > > > > > > pnlDetail.Visible = False > > > > > > > > > > > End If > > > > > > > > > > > Catch ex As SqlException > > > > > > > > > > > lblErrorMsg.Text = ex.message.ToString > > > > > > > > > > > Catch ex As Exception > > > > > > > > > > > lblErrorMsg.Text = ex.Message.ToString > > > > > > > > > > > Finally > > > > > > > > > > > dvwSelect.Dispose() > > > > > > > > > > > End Try > > > > > > > > > > > > > > > > > > > > > > "Phillip Williams" wrote: > > > > > > > > > > > > > > > > > > > > > > > Hi Erik, > > > > > > > > > > > > > > > > > > > > > > > > Good morning to you too and welcome back to the newsgroup. Regarding your > > > > > > > > > > > > code: > > > > > > > > > > > > 1- Server control markup renders into HTML markup when it is processed by > > > > > > > > > > > > the ASP.NET engine. But when you placed it inside the label text, the label > > > > > > > > > > > > control will assume that is a regular HTML markup and would not translate it > > > > > > > > > > > > from being server control markup to HTML > > > > > > > > > > > > 2- The BindParentLabelColumn would not execute unless you add an event > > > > > > > > > > > > hanlder to the lable.databinding event. You could have also wrote the logic > > > > > > > > > > > > within the DataList.ItemDataBound event to achieve the same outcome. > > > > > > > > > > > > 3- If you want your page to handle the click events of the dynamically > > > > > > > > > > > > created image buttons you should databind the list during the Page.Init stage. > > > > > > > > > > > > > > > > > > > > > > > > Here is how I would modify your code: > > > > > > > > > > > > > > > > > > > > > > > > 'starting during the initialization phase of the page's lifecycle > > > > > > > > > > > > Private Sub Page_Init(ByVal sender As System.Object, ByVal e As > > > > > > > > > > > > System.EventArgs) Handles MyBase.Init > > > > > > > > > > > > InitializeComponent() > > > > > > > > > > > > 'Dynamically created controls should be created during the > > > > > > > > > > > > 'page initializtion stage for the control to maintain their viewstate > > > > > > > > > > > > BindControls() > > > > > > > > > > > > End Sub > > > > > > > > > > > > > > > > > > > > > > > > Private Sub BindControls() > > > > > > > > > > > > 'Explicity cast the session variable to its appropriate type before > > > > > > > > > > > > using it > > > > > > > > > > > > datalist1.DataSource = > > > > > > > > > > > > CType(Session("DataList_ParentDetailControls"), DataTable) > > > > > > > > > > > > datalist1.DataBind() > > > > > > > > > > > > > > > > > > > > > > > > End Sub > > > > > > > > > > > > > > > > > > > > > > > > Private Sub DataList1_ItemCreated(ByVal sender As Object, ByVal e As > > > > > > > > > > > > DataListItemEventArgs) Handles datalist1.ItemCreated > > > > > > > > > > > > Dim myLabel As Label = e.Item.FindControl("Label1") > > > > > > > > > > > > 'this step wires up the label databinding event to a method > > > > > > > > > > > > AddHandler myLabel.DataBinding, AddressOf BindParentLabelColumn > > > > > > > > > > > > > > > > > > > > > > > > End Sub > > > > > > > > > > > > > > > > > > > > > > > > Public Sub BindParentLabelColumn(ByVal sender As Object, ByVal e As > > > > > > > > > > > > EventArgs) > > > > > > > > > > > > Dim lbl As Label = CType(sender, Label) > > > > > > > > > > > > Dim container As DataListItem = CType(lbl.NamingContainer, > > > > > > > > > > > > DataListItem) > > > > > > > > > > > > 'the datalistitem has a pointer to the DataItem (which is datarowview) > > > > > > > > > > > > 'of your datatable. Therefore you do not need to retrieve the > > > > > > > > > > > > datatable > > > > > > > > > > > > 'from the session > > > > > > > > > > > > Dim drv As DataRowView = container.DataItem > > > > > > > > > > > > Dim dt As DataTable = drv.Row.Table > > > > > > > > > > > > Dim dc As DataColumn > > > > > > > > > > > > Dim sColumnValue As String > > > > > > > > > > > > Dim sColumnName As String > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > For Each dc In dt.Columns > > > > > > > > > > > > 'you have to add the imagebutton control as a control object to > > > > > > > > > > > > the Hi Phillip,
I have your example working locally, and am working on making it data-driven. Thanks, Erik Show quoteHide quote "Phillip Williams" wrote: > Hi Erik, > > Can you post the code. (I know this page is getting pretty long, so you > might want to chop off the history out of it) > > Also, have you looked at the demo using the datagrid that I posted. It > might prove easier in getting a tidy layout. > -- > HTH, > Phillip Williams > http://www.societopia.net > http://www.webswapp.com > > > "Erik" wrote: > > > Good Morning Phillip, > > Thanks you for the instruction. I have been working through the code, and > > can't figure out an exception I am getting on line Dim drv As DataRowView = > > e.Item.DataItem() in dlstParent1_ItemDataBound. e is Nothing. > > Thanks, Erik > > "Phillip Williams" wrote: > > > > > I managed to put a concept demo that combines the techniques we referred to > > > below: 1) creating templates dynamically, and 2) creating controls > > > dynamically, based on an undetermined number of columns in a datatable. I > > > used here the datagrid instead of the datalist. > > > > > > http://www.societopia.net/Samples/DataGrid_DynamicallyCreatedColumns.aspx > > > > > > -- > > > HTH, > > > Phillip Williams > > > http://www.societopia.net > > > http://www.webswapp.com > > > > > > > > > "Phillip Williams" wrote: > > > > > > > Hi Erik, > > > > > > > > We have just displayed any number of controls (instead of HTML table > > > > columns) into one label (which is inside one ItemTemplate). > > > > > > > > This was just a modification to your original code to explain to you the > > > > concept of building the controls dynamically. (Instead of concatenating > > > > markup text that you started with, you now learned that you could add the > > > > controls dynamically within the page initialization stage to maintain their > > > > functions) > > > > > > > > To reach to a full production outcome of the application that you desire, > > > > you can build on the concepts of adding dynamic controls that we achieved in > > > > this code by refining the way you place the controls. > > > > > > > > For example, instead of using one label you can build a Table within the > > > > DataListItem. You can start by trying a simple markup like this: > > > > > > > > <asp:DataList ID="datalist1" Runat='server' CssClass="Container"> > > > > <ItemTemplate> > > > > <%--leave it empty to be populated programmatically based on # of > > > > columns--%> > > > > </ItemTemplate> > > > > </asp:DataList> > > > > > > > > And then move the code where you created the buttons within the stage of > > > > processing the DataList.ItemDataBound event like this: > > > > > > > > Private Sub DataList1_ItemDataBound(ByVal sender As Object, ByVal e As > > > > DataListItemEventArgs) Handles datalist1.ItemDataBound > > > > Dim drv As DataRowView = e.Item.DataItem() > > > > Dim dt As DataTable = drv.Row.Table > > > > Dim dc As DataColumn > > > > Dim sColumnValue As String > > > > Dim sColumnName As String > > > > 'each row would be formatted as a table that contains one row and as > > > > many cells as there > > > > 'are columns on the datatable > > > > Dim t As New Table > > > > e.Item.Controls.Add(t) 'add the table to the datalist row > > > > Dim r As New TableRow > > > > t.Rows.Add(r) > > > > > > > > For Each dc In dt.Columns > > > > Dim c As New TableCell > > > > r.Cells.Add(c) > > > > 'you have to add the imagebutton control as a control object to > > > > the > > > > 'controls collection of the label so that it would be rendered > > > > by the > > > > 'asp.net engine as a server control > > > > Dim btnImg As New ImageButton > > > > sColumnName = dc.ColumnName > > > > sColumnValue = drv(sColumnName) > > > > btnImg.ID = "Expand" + sColumnName > > > > btnImg.CommandName = "Select" + sColumnName > > > > btnImg.ImageUrl = "images/plus.gif" > > > > c.Controls.Add(btnImg) > > > > 'add the description beside the image button also as a label > > > > control > > > > 'to the original label's controls collection > > > > Dim UrlLabel As New Label > > > > UrlLabel.Text = sColumnValue > > > > c.Controls.Add(UrlLabel) > > > > Next > > > > > > > > End Sub > > > > > > > > Once you get the hang of this you might try a one-more step complex > > > > approach: to dynamically create the ItemTemplates as in this sample: > > > > http://msdn.microsoft.com/library/default.asp?url=/library/en-us/vbcon/html/vbtskcreatingwebservercontroltemplatesdynamically.asp > > > > > > > > If you still cannot get it to work, let me know and I might put a demo of it > > > > on my website. > > > > -- > > > > HTH, > > > > Phillip Williams > > > > http://www.societopia.net > > > > http://www.webswapp.com > > > > > > > > > > > > "Erik" wrote: > > > > > > > > > Is there a way I can define the ItemTemplate labels dynamically in code? The > > > > > number and definition of columns displayed is selected by the user. > > > > > Thanks, Erik > > > > > "Phillip Williams" wrote: > > > > > > > > > > > Hi Erik, > > > > > > > > > > > > That's alright. Label1 is the id of the label that I placed within the > > > > > > DataList markup. You have to give the label an Id to be able to identify it > > > > > > using the FindControl method in the Codebehind. > > > > > > > > > > > > <asp:DataList ID="datalist1" Runat='server' > > > > > > > <ItemTemplate> > > > > > > <asp:Label ID="Label1" Runat="server"></asp:Label>" > > > > > > </ItemTemplate> > > > > > > </asp:DataList> > > > > > > > > > > > > -- > > > > > > HTH, > > > > > > Phillip Williams > > > > > > http://www.societopia.net > > > > > > http://www.webswapp.com > > > > > > > > > > > > > > > > > > "Erik" wrote: > > > > > > > > > > > > > Hi Phillip, > > > > > > > The error is still occurring in > > > > > > > Dim myLabel As Label = e.Item.FindControl("Label1") > > > > > > > AddHandler myLabel.DataBinding, AddressOf BindParentLabelColumn > > > > > > > with the addition below. The ID for the item is Nothing. I can't figure > > > > > > > out what the control 'Label1' refers to since the controls are being created > > > > > > > for the DataList. I apologize for my confusion, but this is new territory > > > > > > > for me again. > > > > > > > Thanks, Erik > > > > > > > > > > > > > > "Phillip Williams" wrote: > > > > > > > > > > > > > > > Correction; the condition should be: > > > > > > > > > > > > > > > > If e.Item.ItemType = ListItemType.Item Or e.Item.ItemType = > > > > > > > > ListItemType.AlternatingItem Then > > > > > > > > '.... > > > > > > > > End IF > > > > > > > > > > > > > > > > "Phillip Williams" wrote: > > > > > > > > > > > > > > > > > Hi Erik, > > > > > > > > > > > > > > > > > > Yes, of course. I exptected you to fill in those tiny details :-) but here > > > > > > > > > is a checked code: > > > > > > > > > > > > > > > > > > Private Sub DataList1_ItemCreated(ByVal sender As Object, ByVal e As > > > > > > > > > DataListItemEventArgs) Handles datalist1.ItemCreated > > > > > > > > > If e.Item.ItemType = ListItemType.Item And e.Item.ItemType = > > > > > > > > > ListItemType.AlternatingItem Then > > > > > > > > > Dim myLabel As Label = e.Item.FindControl("Label1") > > > > > > > > > If Not myLabel Is Nothing Then > > > > > > > > > 'this step wires up the label databinding event to a method > > > > > > > > > AddHandler myLabel.DataBinding, AddressOf > > > > > > > > > BindParentLabelColumn > > > > > > > > > End If > > > > > > > > > End If > > > > > > > > > End Sub > > > > > > > > > > > > > > > > > > -- > > > > > > > > > HTH, > > > > > > > > > Phillip Williams > > > > > > > > > http://www.societopia.net > > > > > > > > > http://www.webswapp.com > > > > > > > > > > > > > > > > > > > > > > > > > > > "Erik" wrote: > > > > > > > > > > > > > > > > > > > Hi Phillip, > > > > > > > > > > It appears the following is causing the error, with an itemtype = 'header'. > > > > > > > > > > Should there be code added to verify the itemtype = 'item'. Thanks, Erik > > > > > > > > > > > > > > > > > > > > Private Sub dlstParent1_ItemCreated(ByVal sender As Object, ByVal e As > > > > > > > > > > DataListItemEventArgs) Handles dlstParent1.ItemCreated > > > > > > > > > > Dim myLabel As Label = e.Item.FindControl("Label1") > > > > > > > > > > 'this step wires up the label databinding event to a method > > > > > > > > > > AddHandler myLabel.DataBinding, AddressOf BindParentLabelColumn > > > > > > > > > > End Sub > > > > > > > > > > > > > > > > > > > > "Phillip Williams" wrote: > > > > > > > > > > > > > > > > > > > > > Hi Erik, > > > > > > > > > > > > > > > > > > > > > > Using VS.Net debugger, set up break points within the methods that are > > > > > > > > > > > triggered upon databinding (of both the datalist and the label) and step > > > > > > > > > > > through them. Somewhere in the code that you did not post, you will find the > > > > > > > > > > > line that threw that exception. > > > > > > > > > > > -- > > > > > > > > > > > HTH, > > > > > > > > > > > Phillip Williams > > > > > > > > > > > http://www.societopia.net > > > > > > > > > > > http://www.webswapp.com > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > "Erik" wrote: > > > > > > > > > > > > > > > > > > > > > > > Hi Phillip, > > > > > > > > > > > > Good to hear from you also. > > > > > > > > > > > > I am encountering an error (Object reference not set to an instance of an > > > > > > > > > > > > object.) on line dlstParent1.DataBind after populating the Parent_Data_Table > > > > > > > > > > > > with the SQL string defined from the user's parameter selection. Do I have > > > > > > > > > > > > some redundant code which is causing a conflict? > > > > > > > > > > > > > > > > > > > > > > > > dlstParent1.HeaderTemplate = > > > > > > > > > > > > New DatalistParentLabelColumn(ListItemType.Header) > > > > > > > > > > > > dlstParent1.ItemTemplate = > > > > > > > > > > > > New DatalistParentLabelColumn(ListItemType.Item) > > > > > > > > > > > > > > > > > > > > > > > > Try > > > > > > > > > > > > dvwSelect = New DataView(Parent_Data_Table(sCmd)) > > > > > > > > > > > > If dvwSelect.Table.Rows.Count <> 0 Then > > > > > > > > > > > > dlstParent1.DataSource = dvwSelect > > > > > > > > > > > > dlstParent1.DataBind() > > > > > > > > > > > > Else > > > > > > > > > > > > Session("DataList_ParentDetailControls") = Nothing > > > > > > > > > > > > pnlDetail.Visible = False > > > > > > > > > > > > End If > > > > > > > > > > > > Catch ex As SqlException > > > > > > > > > > > > lblErrorMsg.Text = ex.message.ToString > > > > > > > > > > > > Catch ex As Exception > > > > > > > > > > > > lblErrorMsg.Text = ex.Message.ToString > > > > > > > > > > > > Finally > > > > > > > > > > > > dvwSelect.Dispose() > > > > > > > > > > > > End Try > > > > > > > > > > > > > > > > > > > > > > > > "Phillip Williams" wrote: > > > > > > > > > > > > > > > > > > > > > > > > > Hi Erik, > > > > > > > > > > > > > > > > > > > > > > > > > > Good morning to you too and welcome back to the newsgroup. Regarding your > > > > > > > > > > > > > code: > > > > > > > > > > > > > 1- Server control markup renders into HTML markup when it is processed by > > > > > > > > > > > > > the ASP.NET engine. But when you placed it inside the label text, the label > > > > > > > > > > > > > control will assume that is a regular HTML markup and would not translate it > > > > > > > > > > > > > from being server control markup to HTML > > > > > > > > > > > > > 2- The BindParentLabelColumn would not execute unless you add an event > > > > > > > > > > > > > hanlder to the lable.databinding event. You could have also wrote the logic > > > > > > > > > > > > > within the DataList.ItemDataBound event to achieve the same outcome. > > > > > > > > > > > > > 3- If you want your page to handle the click events of the dynamically > > > > > > > > > > > > > created image buttons you should databind the list during the Page.Init stage. > > > > > > > > > > > > > > > > > > > > > > > > > > Here is how I would modify your code: > > > > > > > > > > > > > > > > > > > > > > > > > > 'starting during the initialization phase of the page's lifecycle > > > > > > > > > > > > > Private Sub Page_Init(ByVal sender As System.Object, ByVal e As > > > > > > > > > > > > > System.EventArgs) Handles MyBase.Init > > > > > > > > > > > > > InitializeComponent() > > > > > > > > > > > > > 'Dynamically created controls should be created during the > > > > > > > > > > > > > 'page initializtion stage for the control to maintain their viewstate > > > > > > > > > > > > > BindControls() > > > > > > > > > > > > > End Sub > > > > > > > > > > > > > > > > > > > > > > > > > > Private Sub BindControls() > > > > > > > > > > > > > 'Explicity cast the session variable to its appropriate type before > > > > > > > > > > > > > using it > > > > > > > > > > > > > datalist1.DataSource = > > > > > > > > > > > > > CType(Session("DataList_ParentDetailControls"), DataTable) > > > > > > > > > > > > > datalist1.DataBind() > > > > > > > > > > > > > > > > > > > > > > > > > > End Sub > > > > > > > > > > > > > > > > > > > > > > > > > > Private Sub DataList1_ItemCreated(ByVal sender As Object, ByVal e As > > > > > > > > > > > > > DataListItemEventArgs) Handles datalist1.ItemCreated > > > > > > > > > > > > > Dim myLabel As Label = e.Item.FindControl("Label1") > > > > > > > > > > > > > 'this step wires up the label databinding event to a method > > > > > > > > > > > > > AddHandler myLabel.DataBinding, AddressOf BindParentLabelColumn > > > > > > > > > > > > > > > > > > > > > > > > > > End Sub > > > > > > > > > > > > > > > > > > > > > > > > > > Public Sub BindParentLabelColumn(ByVal sender As Object, ByVal e As > > > > > > > > > > > > > EventArgs) > > > > > > > > > > > > > Dim lbl As Label = CType(sender, Label) Good Morning Phillip,
I hope you enjoyed the weekend. I have everything working, and just have two questions regarding the dynamically created controls (imagebutton), and formatting of the databound template columns. When the user clicks the 'plus' button to expand the detail information, the button originally was updated to a 'minus' button. Below is the adapted code for the dynamically created controls: btnDetails = CType(DataGrid1.Items(e.Item.ItemIndex).FindControl(e.CommandName), ImageButton) btnDetails = CType(e.Item.FindControl(e.CommandName.ToString), ImageButton) If Not (btnDetails Is Nothing) Then btnDetails.ImageUrl = "images/minus.gif" Else lblErrorMsg.Text = "Control " & e.CommandName.ToString & " not found." End If The control is not being found, and I can't find the issue with the code. Next, I was wondering if there is a way to format decimal values for the databound template columns. I have been able to accomplish some formatting through the stylesheet, but can't figure out how to explicitly define some columns value to display as currency (in Sub DataGrid1_DataBinding1). For example, if dc.ColumnName = "Price" then display the value as currency. Thank you again for your help. You have again provided wonderful instruction and patience. Erik Show quoteHide quote "Erik" wrote: > Hi Phillip, > I have your example working locally, and am working on making it data-driven. > Thanks, > Erik > > "Phillip Williams" wrote: > > > Hi Erik, > > > > Can you post the code. (I know this page is getting pretty long, so you > > might want to chop off the history out of it) > > > > Also, have you looked at the demo using the datagrid that I posted. It > > might prove easier in getting a tidy layout. > > -- > > HTH, > > Phillip Williams > > http://www.societopia.net > > http://www.webswapp.com > > > > > > "Erik" wrote: > > > > > Good Morning Phillip, > > > Thanks you for the instruction. I have been working through the code, and > > > can't figure out an exception I am getting on line Dim drv As DataRowView = > > > e.Item.DataItem() in dlstParent1_ItemDataBound. e is Nothing. > > > Thanks, Erik > > > "Phillip Williams" wrote: > > > > > > > I managed to put a concept demo that combines the techniques we referred to > > > > below: 1) creating templates dynamically, and 2) creating controls > > > > dynamically, based on an undetermined number of columns in a datatable. I > > > > used here the datagrid instead of the datalist. > > > > > > > > http://www.societopia.net/Samples/DataGrid_DynamicallyCreatedColumns.aspx > > > > > > > > -- > > > > HTH, > > > > Phillip Williams > > > > http://www.societopia.net > > > > http://www.webswapp.com > > > > > > > > > > > > "Phillip Williams" wrote: > > > > > > > > > Hi Erik, > > > > > > > > > > We have just displayed any number of controls (instead of HTML table > > > > > columns) into one label (which is inside one ItemTemplate). > > > > > > > > > > This was just a modification to your original code to explain to you the > > > > > concept of building the controls dynamically. (Instead of concatenating > > > > > markup text that you started with, you now learned that you could add the > > > > > controls dynamically within the page initialization stage to maintain their > > > > > functions) > > > > > > > > > > To reach to a full production outcome of the application that you desire, > > > > > you can build on the concepts of adding dynamic controls that we achieved in > > > > > this code by refining the way you place the controls. > > > > > > > > > > For example, instead of using one label you can build a Table within the > > > > > DataListItem. You can start by trying a simple markup like this: > > > > > > > > > > <asp:DataList ID="datalist1" Runat='server' CssClass="Container"> > > > > > <ItemTemplate> > > > > > <%--leave it empty to be populated programmatically based on # of > > > > > columns--%> > > > > > </ItemTemplate> > > > > > </asp:DataList> > > > > > > > > > > And then move the code where you created the buttons within the stage of > > > > > processing the DataList.ItemDataBound event like this: > > > > > > > > > > Private Sub DataList1_ItemDataBound(ByVal sender As Object, ByVal e As > > > > > DataListItemEventArgs) Handles datalist1.ItemDataBound > > > > > Dim drv As DataRowView = e.Item.DataItem() > > > > > Dim dt As DataTable = drv.Row.Table > > > > > Dim dc As DataColumn > > > > > Dim sColumnValue As String > > > > > Dim sColumnName As String > > > > > 'each row would be formatted as a table that contains one row and as > > > > > many cells as there > > > > > 'are columns on the datatable > > > > > Dim t As New Table > > > > > e.Item.Controls.Add(t) 'add the table to the datalist row > > > > > Dim r As New TableRow > > > > > t.Rows.Add(r) > > > > > > > > > > For Each dc In dt.Columns > > > > > Dim c As New TableCell > > > > > r.Cells.Add(c) > > > > > 'you have to add the imagebutton control as a control object to > > > > > the > > > > > 'controls collection of the label so that it would be rendered > > > > > by the > > > > > 'asp.net engine as a server control > > > > > Dim btnImg As New ImageButton > > > > > sColumnName = dc.ColumnName > > > > > sColumnValue = drv(sColumnName) > > > > > btnImg.ID = "Expand" + sColumnName > > > > > btnImg.CommandName = "Select" + sColumnName > > > > > btnImg.ImageUrl = "images/plus.gif" > > > > > c.Controls.Add(btnImg) > > > > > 'add the description beside the image button also as a label > > > > > control > > > > > 'to the original label's controls collection > > > > > Dim UrlLabel As New Label > > > > > UrlLabel.Text = sColumnValue > > > > > c.Controls.Add(UrlLabel) > > > > > Next > > > > > > > > > > End Sub > > > > > > > > > > Once you get the hang of this you might try a one-more step complex > > > > > approach: to dynamically create the ItemTemplates as in this sample: > > > > > http://msdn.microsoft.com/library/default.asp?url=/library/en-us/vbcon/html/vbtskcreatingwebservercontroltemplatesdynamically.asp > > > > > > > > > > If you still cannot get it to work, let me know and I might put a demo of it > > > > > on my website. > > > > > -- > > > > > HTH, > > > > > Phillip Williams > > > > > http://www.societopia.net > > > > > http://www.webswapp.com > > > > > > > > > > > > > > > "Erik" wrote: > > > > > > > > > > > Is there a way I can define the ItemTemplate labels dynamically in code? The > > > > > > number and definition of columns displayed is selected by the user. > > > > > > Thanks, Erik > > > > > > "Phillip Williams" wrote: > > > > > > > > > > > > > Hi Erik, > > > > > > > > > > > > > > That's alright. Label1 is the id of the label that I placed within the > > > > > > > DataList markup. You have to give the label an Id to be able to identify it > > > > > > > using the FindControl method in the Codebehind. > > > > > > > > > > > > > > <asp:DataList ID="datalist1" Runat='server' > > > > > > > > <ItemTemplate> > > > > > > > <asp:Label ID="Label1" Runat="server"></asp:Label>" > > > > > > > </ItemTemplate> > > > > > > > </asp:DataList> > > > > > > > > > > > > > > -- > > > > > > > HTH, > > > > > > > Phillip Williams > > > > > > > http://www.societopia.net > > > > > > > http://www.webswapp.com > > > > > > > > > > > > > > > > > > > > > "Erik" wrote: > > > > > > > > > > > > > > > Hi Phillip, > > > > > > > > The error is still occurring in > > > > > > > > Dim myLabel As Label = e.Item.FindControl("Label1") > > > > > > > > AddHandler myLabel.DataBinding, AddressOf BindParentLabelColumn > > > > > > > > with the addition below. The ID for the item is Nothing. I can't figure > > > > > > > > out what the control 'Label1' refers to since the controls are being created > > > > > > > > for the DataList. I apologize for my confusion, but this is new territory > > > > > > > > for me again. > > > > > > > > Thanks, Erik > > > > > > > > > > > > > > > > "Phillip Williams" wrote: > > > > > > > > > > > > > > > > > Correction; the condition should be: > > > > > > > > > > > > > > > > > > If e.Item.ItemType = ListItemType.Item Or e.Item.ItemType = > > > > > > > > > ListItemType.AlternatingItem Then > > > > > > > > > '.... > > > > > > > > > End IF > > > > > > > > > > > > > > > > > > "Phillip Williams" wrote: > > > > > > > > > > > > > > > > > > > Hi Erik, > > > > > > > > > > > > > > > > > > > > Yes, of course. I exptected you to fill in those tiny details :-) but here > > > > > > > > > > is a checked code: > > > > > > > > > > > > > > > > > > > > Private Sub DataList1_ItemCreated(ByVal sender As Object, ByVal e As > > > > > > > > > > DataListItemEventArgs) Handles datalist1.ItemCreated > > > > > > > > > > If e.Item.ItemType = ListItemType.Item And e.Item.ItemType = > > > > > > > > > > ListItemType.AlternatingItem Then > > > > > > > > > > Dim myLabel As Label = e.Item.FindControl("Label1") > > > > > > > > > > If Not myLabel Is Nothing Then > > > > > > > > > > 'this step wires up the label databinding event to a method > > > > > > > > > > AddHandler myLabel.DataBinding, AddressOf > > > > > > > > > > BindParentLabelColumn > > > > > > > > > > End If > > > > > > > > > > End If > > > > > > > > > > End Sub > > > > > > > > > > > > > > > > > > > > -- > > > > > > > > > > HTH, > > > > > > > > > > Phillip Williams > > > > > > > > > > http://www.societopia.net > > > > > > > > > > http://www.webswapp.com > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > "Erik" wrote: > > > > > > > > > > > > > > > > > > > > > Hi Phillip, > > > > > > > > > > > It appears the following is causing the error, with an itemtype = 'header'. > > > > > > > > > > > Should there be code added to verify the itemtype = 'item'. Thanks, Erik > > > > > > > > > > > > > > > > > > > > > > Private Sub dlstParent1_ItemCreated(ByVal sender As Object, ByVal e As > > > > > > > > > > > DataListItemEventArgs) Handles dlstParent1.ItemCreated > > > > > > > > > > > Dim myLabel As Label = e.Item.FindControl("Label1") > > > > > > > > > > > 'this step wires up the label databinding event to a method > > > > > > > > > > > AddHandler myLabel.DataBinding, AddressOf BindParentLabelColumn > > > > > > > > > > > End Sub > > > > > > > > > > > > > > > > > > > > > > "Phillip Williams" wrote: > > > > > > > > > > > > > > > > > > > > > > > Hi Erik, > > > > > > > > > > > > > > > > > > > > > > > > Using VS.Net debugger, set up break points within the methods that are > > > > > > > > > > > > triggered upon databinding (of both the datalist and the label) and step > > > > > > > > > > > > through them. Somewhere in the code that you did not post, you will find the > > > > > > > > > > > > line that threw that exception. > > > > > > > > > > > > -- > > > > > > > > > > > > HTH, > > > > > > > > > > > > Phillip Williams > > > > > > > > > > > > http://www.societopia.net > > > > > > > > > > > > http://www.webswapp.com > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > "Erik" wrote: > > > > > > > > > > > > > > > > > > > > > > > > > Hi Phillip, > > > > > > > > > > > > > Good to hear from you also. > > > > > > > > > > > > > I am encountering an error (Object reference not set to an instance of an > > > > > > > > > > > > > object.) on line dlstParent1.DataBind after populating the Parent_Data_Table > > > > > > > > > > > > > with the SQL string defined from the user's parameter selection. Do I have > > > > > > > > > > > > > some redundant code which is causing a conflict? > > > > > > > > > > > > > > > > > > > > > > > > > > dlstParent1.HeaderTemplate = > > > > > > > > > > > > > New DatalistParentLabelColumn(ListItemType.Header) > > > > > > > > > > > > > dlstParent1.ItemTemplate = > > > > > > > > > > > > > New DatalistParentLabelColumn(ListItemType.Item) > > > > > > > > > > > > > > > > > > > > > > > > > > Try > > > > > > > > > > > > > dvwSelect = New DataView(Parent_Data_Table(sCmd)) > > > > > > > > > > > > > If dvwSelect.Table.Rows.Count <> 0 Then > > > > > > > > > > > > > dlstParent1.DataSource = dvwSelect > > > > > > > > > > > > > dlstParent1.DataBind() > > > > > > > > > > > > > Else > > > > > > > > > > > > > Session("DataList_ParentDetailControls") = Nothing > > > > > > > > > > > > > pnlDetail.Visible = False > > > > > > > > > > > > > End If > > > > > > > > > > > > > Catch ex As SqlException > > > > > > > > > > > > > lblErrorMsg.Text = ex.message.ToString > > > > > > > > > > > > > Catch ex As Exception > > > > > > > > > > > > > lblErrorMsg.Text = ex.Message.ToString > > > > > > > > > > > > > Finally > > > > > > > > > > > > > dvwSelect.Dispose() > > > > > > > > > > > > > End Try > > > > > > > > > > > > > > > > > > > > > > > > > > "Phillip Williams" wrote: > > > > > > > > > > > > > > > > > > > > > > > > > > > Hi Erik, > > > > > > > > > > > > > > > > > > > > > > > > > > > > Good morning to you too and welcome back to the newsgroup. Regarding your > > > > > > > > > > > > > > code: > > > > > > > > > > > > > > 1- Server control markup renders into HTML markup when it is processed by > > > > > > > > > > > > > > the ASP.NET engine. But when you placed it inside the label text, the label > > > > > > > > > > > > > > control will assume that is a regular HTML markup and would not translate it > > > > > > > > > > > > > > from being server control markup to HTML > > > > > > > > > > > > > > 2- The BindParentLabelColumn would not execute unless you add an event > > > > > > > > > > > > > > hanlder to the lable.databinding event. You could have also wrote the logic > > > > > > > > > > > > > > within the DataList.ItemDataBound event to achieve the same outcome. > > > > > > > > > > > > > > 3- If you want your page to handle the click events of the dynamically > > > > > > > > > > > > > > created image buttons you should databind the list during the Page.Init stage. > > > > > > > > > > > > > > > > > > > > > > > > > > > > Here is how I would modify your code: > > > > > > > > > > > > > > > > > > > > > > > > > > > > 'starting during the initialization phase of the page's lifecycle > > > > > > > > > > > > > > Private Sub Page_Init(ByVal sender As System.Object, ByVal e As > > > > > > > > > > > > > > System.EventArgs) Handles MyBase.Init > > > > > > > > > > > > > > InitializeComponent() > > > > > > > > > > > > > > 'Dynamically created controls should be created during the > > > > > > > > > > > > > > 'page initializtion stage for the control to maintain their viewstate > > > > > > > > > > > > > > BindControls() > > > > > > > > > > > > > > End Sub > > > > > > > > > > > > > > > > > > > > > > > > > > > > Private Sub BindControls() > > > > > > > > > > > > > > 'Explicity cast the session variable to its appropriate type before > > > > > > > > > > > > > > using it > > > > > > > > > > > > > > datalist1.DataSource = > > > > > > > > > > > > > > CType(Session("DataList_ParentDetailControls"), DataTable) > > > > > > > > > > > > > > datalist1.DataBind() > > > > > > > > > > > > > > > > > > > > > > > > > > > > End Sub > > > > > > > > > > > > > > > > > > > > > > > > > > > > Private Sub DataList1_ItemCreated(ByVal sender As Object, ByVal e As > > > > > > > > > > > > > > DataListItemEventArgs) Handles datalist1.ItemCreated > > > > > > > > > > > > > > Dim myLabel As Label = e.Item.FindControl("Label1") > > > > > > > > > > > > > > 'this step wires up the label databinding event to a method Hi Erik,
You are quite welcome. To be able to refer to the buttons you need to give them IDs (I noticed that you used the commandName; while I would prefer to use the CommandArgument). I modified the original demo accordingly: http://www.societopia.net/samples/DataGrid_DynamicallyCreatedColumns.aspx As for formatting a number as currency you can use the DataFormatString property of the BoundColumn like this DataFormatString = "{0:C}" Show quoteHide quote "Erik" wrote: > Good Morning Phillip, > I hope you enjoyed the weekend. I have everything working, and just have > two questions regarding the dynamically created controls (imagebutton), and > formatting of the databound template columns. > When the user clicks the 'plus' button to expand the detail information, the > button originally was updated to a 'minus' button. Below is the adapted code > for the dynamically created controls: > btnDetails = > CType(DataGrid1.Items(e.Item.ItemIndex).FindControl(e.CommandName), > ImageButton) > btnDetails = CType(e.Item.FindControl(e.CommandName.ToString), ImageButton) > If Not (btnDetails Is Nothing) Then > btnDetails.ImageUrl = "images/minus.gif" > Else > lblErrorMsg.Text = "Control " & e.CommandName.ToString & " not found." > End If > The control is not being found, and I can't find the issue with the code. > Next, I was wondering if there is a way to format decimal values for the > databound template columns. I have been able to accomplish some formatting > through the stylesheet, but can't figure out how to explicitly define some > columns value to display as currency (in Sub DataGrid1_DataBinding1). For > example, if dc.ColumnName = "Price" then display the value as currency. > Thank you again for your help. You have again provided wonderful > instruction and patience. > Erik > > > "Erik" wrote: > > > Hi Phillip, > > I have your example working locally, and am working on making it data-driven. > > Thanks, > > Erik > > > > "Phillip Williams" wrote: > > > > > Hi Erik, > > > > > > Can you post the code. (I know this page is getting pretty long, so you > > > might want to chop off the history out of it) > > > > > > Also, have you looked at the demo using the datagrid that I posted. It > > > might prove easier in getting a tidy layout. > > > -- > > > HTH, > > > Phillip Williams > > > http://www.societopia.net > > > http://www.webswapp.com > > > > > > > > > "Erik" wrote: > > > > > > > Good Morning Phillip, > > > > Thanks you for the instruction. I have been working through the code, and > > > > can't figure out an exception I am getting on line Dim drv As DataRowView = > > > > e.Item.DataItem() in dlstParent1_ItemDataBound. e is Nothing. > > > > Thanks, Erik > > > > "Phillip Williams" wrote: > > > > > > > > > I managed to put a concept demo that combines the techniques we referred to > > > > > below: 1) creating templates dynamically, and 2) creating controls > > > > > dynamically, based on an undetermined number of columns in a datatable. I > > > > > used here the datagrid instead of the datalist. > > > > > > > > > > http://www.societopia.net/Samples/DataGrid_DynamicallyCreatedColumns.aspx > > > > > > > > > > -- > > > > > HTH, > > > > > Phillip Williams > > > > > http://www.societopia.net > > > > > http://www.webswapp.com > > > > > > > > > > > > > > > "Phillip Williams" wrote: > > > > > > > > > > > Hi Erik, > > > > > > > > > > > > We have just displayed any number of controls (instead of HTML table > > > > > > columns) into one label (which is inside one ItemTemplate). > > > > > > > > > > > > This was just a modification to your original code to explain to you the > > > > > > concept of building the controls dynamically. (Instead of concatenating > > > > > > markup text that you started with, you now learned that you could add the > > > > > > controls dynamically within the page initialization stage to maintain their > > > > > > functions) > > > > > > > > > > > > To reach to a full production outcome of the application that you desire, > > > > > > you can build on the concepts of adding dynamic controls that we achieved in > > > > > > this code by refining the way you place the controls. > > > > > > > > > > > > For example, instead of using one label you can build a Table within the > > > > > > DataListItem. You can start by trying a simple markup like this: > > > > > > > > > > > > <asp:DataList ID="datalist1" Runat='server' CssClass="Container"> > > > > > > <ItemTemplate> > > > > > > <%--leave it empty to be populated programmatically based on # of > > > > > > columns--%> > > > > > > </ItemTemplate> > > > > > > </asp:DataList> > > > > > > > > > > > > And then move the code where you created the buttons within the stage of > > > > > > processing the DataList.ItemDataBound event like this: > > > > > > > > > > > > Private Sub DataList1_ItemDataBound(ByVal sender As Object, ByVal e As > > > > > > DataListItemEventArgs) Handles datalist1.ItemDataBound > > > > > > Dim drv As DataRowView = e.Item.DataItem() > > > > > > Dim dt As DataTable = drv.Row.Table > > > > > > Dim dc As DataColumn > > > > > > Dim sColumnValue As String > > > > > > Dim sColumnName As String > > > > > > 'each row would be formatted as a table that contains one row and as > > > > > > many cells as there > > > > > > 'are columns on the datatable > > > > > > Dim t As New Table > > > > > > e.Item.Controls.Add(t) 'add the table to the datalist row > > > > > > Dim r As New TableRow > > > > > > t.Rows.Add(r) > > > > > > > > > > > > For Each dc In dt.Columns > > > > > > Dim c As New TableCell > > > > > > r.Cells.Add(c) > > > > > > 'you have to add the imagebutton control as a control object to > > > > > > the > > > > > > 'controls collection of the label so that it would be rendered > > > > > > by the > > > > > > 'asp.net engine as a server control > > > > > > Dim btnImg As New ImageButton > > > > > > sColumnName = dc.ColumnName > > > > > > sColumnValue = drv(sColumnName) > > > > > > btnImg.ID = "Expand" + sColumnName > > > > > > btnImg.CommandName = "Select" + sColumnName > > > > > > btnImg.ImageUrl = "images/plus.gif" > > > > > > c.Controls.Add(btnImg) > > > > > > 'add the description beside the image button also as a label > > > > > > control > > > > > > 'to the original label's controls collection > > > > > > Dim UrlLabel As New Label > > > > > > UrlLabel.Text = sColumnValue > > > > > > c.Controls.Add(UrlLabel) > > > > > > Next > > > > > > > > > > > > End Sub > > > > > > > > > > > > Once you get the hang of this you might try a one-more step complex > > > > > > approach: to dynamically create the ItemTemplates as in this sample: > > > > > > http://msdn.microsoft.com/library/default.asp?url=/library/en-us/vbcon/html/vbtskcreatingwebservercontroltemplatesdynamically.asp > > > > > > > > > > > > If you still cannot get it to work, let me know and I might put a demo of it > > > > > > on my website. > > > > > > -- > > > > > > HTH, > > > > > > Phillip Williams > > > > > > http://www.societopia.net > > > > > > http://www.webswapp.com > > > > > > > > > > > > > > > > > > "Erik" wrote: > > > > > > > > > > > > > Is there a way I can define the ItemTemplate labels dynamically in code? The > > > > > > > number and definition of columns displayed is selected by the user. > > > > > > > Thanks, Erik > > > > > > > "Phillip Williams" wrote: > > > > > > > > > > > > > > > Hi Erik, > > > > > > > > > > > > > > > > That's alright. Label1 is the id of the label that I placed within the > > > > > > > > DataList markup. You have to give the label an Id to be able to identify it > > > > > > > > using the FindControl method in the Codebehind. > > > > > > > > > > > > > > > > <asp:DataList ID="datalist1" Runat='server' > > > > > > > > > <ItemTemplate> > > > > > > > > <asp:Label ID="Label1" Runat="server"></asp:Label>" > > > > > > > > </ItemTemplate> > > > > > > > > </asp:DataList> > > > > > > > > > > > > > > > > -- > > > > > > > > HTH, > > > > > > > > Phillip Williams > > > > > > > > http://www.societopia.net > > > > > > > > http://www.webswapp.com > > > > > > > > > > > > > > > > > > > > > > > > "Erik" wrote: > > > > > > > > > > > > > > > > > Hi Phillip, > > > > > > > > > The error is still occurring in > > > > > > > > > Dim myLabel As Label = e.Item.FindControl("Label1") > > > > > > > > > AddHandler myLabel.DataBinding, AddressOf BindParentLabelColumn > > > > > > > > > with the addition below. The ID for the item is Nothing. I can't figure > > > > > > > > > out what the control 'Label1' refers to since the controls are being created > > > > > > > > > for the DataList. I apologize for my confusion, but this is new territory > > > > > > > > > for me again. > > > > > > > > > Thanks, Erik > > > > > > > > > > > > > > > > > > "Phillip Williams" wrote: > > > > > > > > > > > > > > > > > > > Correction; the condition should be: > > > > > > > > > > > > > > > > > > > > If e.Item.ItemType = ListItemType.Item Or e.Item.ItemType = > > > > > > > > > > ListItemType.AlternatingItem Then > > > > > > > > > > '.... > > > > > > > > > > End IF > > > > > > > > > > > > > > > > > > > > "Phillip Williams" wrote: > > > > > > > > > > > > > > > > > > > > > Hi Erik, > > > > > > > > > > > > > > > > > > > > > > Yes, of course. I exptected you to fill in those tiny details :-) but here > > > > > > > > > > > is a checked code: > > > > > > > > > > > > > > > > > > > > > > Private Sub DataList1_ItemCreated(ByVal sender As Object, ByVal e As > > > > > > > > > > > DataListItemEventArgs) Handles datalist1.ItemCreated > > > > > > > > > > > If e.Item.ItemType = ListItemType.Item And e.Item.ItemType = > > > > > > > > > > > ListItemType.AlternatingItem Then > > > > > > > > > > > Dim myLabel As Label = e.Item.FindControl("Label1") > > > > > > > > > > > If Not myLabel Is Nothing Then > > > > > > > > > > > 'this step wires up the label databinding event to a method > > > > > > > > > > > AddHandler myLabel.DataBinding, AddressOf > > > > > > > > > > > BindParentLabelColumn > > > > > > > > > > > End If > > > > > > > > > > > End If > > > > > > > > > > > End Sub > > > > > > > > > > > > > > > > > > > > > > -- > > > > > > > > > > > HTH, > > > > > > > > > > > Phillip Williams > > > > > > > > > > > http://www.societopia.net > > > > > > > > > > > http://www.webswapp.com > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > "Erik" wrote: > > > > > > > > > > > > > > > > > > > > > > > Hi Phillip, > > > > > > > > > > > > It appears the following is causing the error, with an itemtype = 'header'. > > > > > > > > > > > > Should there be code added to verify the itemtype = 'item'. Thanks, Erik > > > > > > > > > > > > > > > > > > > > > > > > Private Sub dlstParent1_ItemCreated(ByVal sender As Object, ByVal e As > > > > > > > > > > > > DataListItemEventArgs) Handles dlstParent1.ItemCreated > > > > > > > > > > > > Dim myLabel As Label = e.Item.FindControl("Label1") > > > > > > > > > > > > 'this step wires up the label databinding event to a method > > > > > > > > > > > > AddHandler myLabel.DataBinding, AddressOf BindParentLabelColumn > > > > > > > > > > > > End Sub > > > > > > > > > > > > > > > > > > > > > > > > "Phillip Williams" wrote: > > > > > > > > > > > > > > > > > > > > > > > > > Hi Erik, > > > > > > > > > > > > > > > > > > > > > > > > > > Using VS.Net debugger, set up break points within the methods that are > > > > > > > > > > > > > triggered upon databinding (of both the datalist and the label) and step > > > > > > > > > > > > > through them. Somewhere in the code that you did not post, you will find the > > > > > > > > > > > > > line that threw that exception. > > > > > > > > > > > > > -- > > > > > > > > > > > > > HTH, > > > > > > > > > > > > > Phillip Williams > > > > > > > > > > > > > http://www.societopia.net > > > > > > > > > > > > > http://www.webswapp.com > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > "Erik" wrote: > > > > > > > > > > > > > > > > > > > > > > > > > > > Hi Phillip, > > > > > > > > > > > > > > Good to hear from you also. > > > > > > > > > > > > > > I am encountering an error (Object reference not set to an instance of an > > > > > > > > > > > > > > object.) on line dlstParent1.DataBind after populating the Parent_Data_Table > > > > > > > > > > > > > > with the SQL string defined from the user's parameter selection. Do I have > > > > > > > > > > > > > > some redundant code which is causing a conflict? > > > > > > > > > > > > > > > > > > > > > > > > > > > > dlstParent1.HeaderTemplate = > > > > > > > > > > > > > > New DatalistParentLabelColumn(ListItemType.Header) > > > > > > > > > > > > > > dlstParent1.ItemTemplate = > > > > > > > > > > > > > > New DatalistParentLabelColumn(ListItemType.Item) > > > > > > > > > > > > > > > > > > > > > > > > > > > > Try > > > > > > > > > > > > > > dvwSelect = New DataView(Parent_Data_Table(sCmd)) > > > > > > > > > > > > > > If dvwSelect.Table.Rows.Count <> 0 Then > > > > > > > > > > > > > > dlstParent1.DataSource = dvwSelect > > > > > > > > > > > > > > dlstParent1.DataBind() > > > > > > > > > > > > > > Else > > > > > > > > > > > > > > Session("DataList_ParentDetailControls") = Nothing > > > > > > > > > > > > > > pnlDetail.Visible = False > > > > > > > > > > > > > > End If > > > > > > > > > > > > > > Catch ex As SqlException > > > > > > > > > > > > > > lblErrorMsg.Text = ex.message.ToString > > > > > > > > > > > > > > Catch ex As Exception > > > > > > > > > > > > > > lblErrorMsg.Text = ex.Message.ToString > > > > > > > > > > > > > > Finally > > > > > > > > > > > > > > dvwSelect.Dispose() > > > > > > > > > > > > > > End Try > > > > > > > > > > > > > > > > > > > > > > > > > > > > "Phillip Williams" wrote: > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Hi Erik, > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Good morning to you too and welcome back to the newsgroup. Regarding your > > > > > > > > > > > > > > > code: > > > > > > > > > > > > > > > 1- Server control markup renders into HTML markup when it is processed by > > > > > > > > > > > > > > > the ASP.NET engine. But when you placed it inside the label text, the label > > > > > > > > > > > > > > > control will assume that is a regular HTML markup and would not translate it > > > > > > > > > > > > > > > from being server control markup to HTML > > > > > > > > > > > > > > > 2- The BindParentLabelColumn would not execute unless you add an event Good Morning Phillip,
I was unable to see in your code where imgBtn.ImageUrl is assigned to left.gif. Would you please point out in which function / sub the assignment takes place? Another question I had was calling the 'CreateTable' function twice in Page_Init. Isn't datagrid1.DataSource = CreateTable() sufficient to create the table for databinding? Thanks, Erik Show quoteHide quote "Phillip Williams" wrote: > Hi Erik, > > You are quite welcome. To be able to refer to the buttons you need to give > them IDs (I noticed that you used the commandName; while I would prefer to > use the CommandArgument). I modified the original demo accordingly: > http://www.societopia.net/samples/DataGrid_DynamicallyCreatedColumns.aspx > > As for formatting a number as currency you can use the DataFormatString > property of the BoundColumn like this DataFormatString = "{0:C}" > > -- > HTH, > Phillip Williams > http://www.societopia.net > http://www.webswapp.com > > > "Erik" wrote: > > > Good Morning Phillip, > > I hope you enjoyed the weekend. I have everything working, and just have > > two questions regarding the dynamically created controls (imagebutton), and > > formatting of the databound template columns. > > When the user clicks the 'plus' button to expand the detail information, the > > button originally was updated to a 'minus' button. Below is the adapted code > > for the dynamically created controls: > > btnDetails = > > CType(DataGrid1.Items(e.Item.ItemIndex).FindControl(e.CommandName), > > ImageButton) > > btnDetails = CType(e.Item.FindControl(e.CommandName.ToString), ImageButton) > > If Not (btnDetails Is Nothing) Then > > btnDetails.ImageUrl = "images/minus.gif" > > Else > > lblErrorMsg.Text = "Control " & e.CommandName.ToString & " not found." > > End If > > The control is not being found, and I can't find the issue with the code. > > Next, I was wondering if there is a way to format decimal values for the > > databound template columns. I have been able to accomplish some formatting > > through the stylesheet, but can't figure out how to explicitly define some > > columns value to display as currency (in Sub DataGrid1_DataBinding1). For > > example, if dc.ColumnName = "Price" then display the value as currency. > > Thank you again for your help. You have again provided wonderful > > instruction and patience. > > Erik > > > > > > "Erik" wrote: > > > > > Hi Phillip, > > > I have your example working locally, and am working on making it data-driven. > > > Thanks, > > > Erik > > > > > > "Phillip Williams" wrote: > > > > > > > Hi Erik, > > > > > > > > Can you post the code. (I know this page is getting pretty long, so you > > > > might want to chop off the history out of it) > > > > > > > > Also, have you looked at the demo using the datagrid that I posted. It > > > > might prove easier in getting a tidy layout. > > > > -- > > > > HTH, > > > > Phillip Williams > > > > http://www.societopia.net > > > > http://www.webswapp.com > > > > > > > > > > > > "Erik" wrote: > > > > > > > > > Good Morning Phillip, > > > > > Thanks you for the instruction. I have been working through the code, and > > > > > can't figure out an exception I am getting on line Dim drv As DataRowView = > > > > > e.Item.DataItem() in dlstParent1_ItemDataBound. e is Nothing. > > > > > Thanks, Erik > > > > > "Phillip Williams" wrote: > > > > > > > > > > > I managed to put a concept demo that combines the techniques we referred to > > > > > > below: 1) creating templates dynamically, and 2) creating controls > > > > > > dynamically, based on an undetermined number of columns in a datatable. I > > > > > > used here the datagrid instead of the datalist. > > > > > > > > > > > > http://www.societopia.net/Samples/DataGrid_DynamicallyCreatedColumns.aspx > > > > > > > > > > > > -- > > > > > > HTH, > > > > > > Phillip Williams > > > > > > http://www.societopia.net > > > > > > http://www.webswapp.com > > > > > > > > > > > > > > > > > > "Phillip Williams" wrote: > > > > > > > > > > > > > Hi Erik, > > > > > > > > > > > > > > We have just displayed any number of controls (instead of HTML table > > > > > > > columns) into one label (which is inside one ItemTemplate). > > > > > > > > > > > > > > This was just a modification to your original code to explain to you the > > > > > > > concept of building the controls dynamically. (Instead of concatenating > > > > > > > markup text that you started with, you now learned that you could add the > > > > > > > controls dynamically within the page initialization stage to maintain their > > > > > > > functions) > > > > > > > > > > > > > > To reach to a full production outcome of the application that you desire, > > > > > > > you can build on the concepts of adding dynamic controls that we achieved in > > > > > > > this code by refining the way you place the controls. > > > > > > > > > > > > > > For example, instead of using one label you can build a Table within the > > > > > > > DataListItem. You can start by trying a simple markup like this: > > > > > > > > > > > > > > <asp:DataList ID="datalist1" Runat='server' CssClass="Container"> > > > > > > > <ItemTemplate> > > > > > > > <%--leave it empty to be populated programmatically based on # of > > > > > > > columns--%> > > > > > > > </ItemTemplate> > > > > > > > </asp:DataList> > > > > > > > > > > > > > > And then move the code where you created the buttons within the stage of > > > > > > > processing the DataList.ItemDataBound event like this: > > > > > > > > > > > > > > Private Sub DataList1_ItemDataBound(ByVal sender As Object, ByVal e As > > > > > > > DataListItemEventArgs) Handles datalist1.ItemDataBound > > > > > > > Dim drv As DataRowView = e.Item.DataItem() > > > > > > > Dim dt As DataTable = drv.Row.Table > > > > > > > Dim dc As DataColumn > > > > > > > Dim sColumnValue As String > > > > > > > Dim sColumnName As String > > > > > > > 'each row would be formatted as a table that contains one row and as > > > > > > > many cells as there > > > > > > > 'are columns on the datatable > > > > > > > Dim t As New Table > > > > > > > e.Item.Controls.Add(t) 'add the table to the datalist row > > > > > > > Dim r As New TableRow > > > > > > > t.Rows.Add(r) > > > > > > > > > > > > > > For Each dc In dt.Columns > > > > > > > Dim c As New TableCell > > > > > > > r.Cells.Add(c) > > > > > > > 'you have to add the imagebutton control as a control object to > > > > > > > the > > > > > > > 'controls collection of the label so that it would be rendered > > > > > > > by the > > > > > > > 'asp.net engine as a server control > > > > > > > Dim btnImg As New ImageButton > > > > > > > sColumnName = dc.ColumnName > > > > > > > sColumnValue = drv(sColumnName) > > > > > > > btnImg.ID = "Expand" + sColumnName > > > > > > > btnImg.CommandName = "Select" + sColumnName > > > > > > > btnImg.ImageUrl = "images/plus.gif" > > > > > > > c.Controls.Add(btnImg) > > > > > > > 'add the description beside the image button also as a label > > > > > > > control > > > > > > > 'to the original label's controls collection > > > > > > > Dim UrlLabel As New Label > > > > > > > UrlLabel.Text = sColumnValue > > > > > > > c.Controls.Add(UrlLabel) > > > > > > > Next > > > > > > > > > > > > > > End Sub > > > > > > > > > > > > > > Once you get the hang of this you might try a one-more step complex > > > > > > > approach: to dynamically create the ItemTemplates as in this sample: > > > > > > > http://msdn.microsoft.com/library/default.asp?url=/library/en-us/vbcon/html/vbtskcreatingwebservercontroltemplatesdynamically.asp > > > > > > > > > > > > > > If you still cannot get it to work, let me know and I might put a demo of it > > > > > > > on my website. > > > > > > > -- > > > > > > > HTH, > > > > > > > Phillip Williams > > > > > > > http://www.societopia.net > > > > > > > http://www.webswapp.com > > > > > > > > > > > > > > > > > > > > > "Erik" wrote: > > > > > > > > > > > > > > > Is there a way I can define the ItemTemplate labels dynamically in code? The > > > > > > > > number and definition of columns displayed is selected by the user. > > > > > > > > Thanks, Erik > > > > > > > > "Phillip Williams" wrote: > > > > > > > > > > > > > > > > > Hi Erik, > > > > > > > > > > > > > > > > > > That's alright. Label1 is the id of the label that I placed within the > > > > > > > > > DataList markup. You have to give the label an Id to be able to identify it > > > > > > > > > using the FindControl method in the Codebehind. > > > > > > > > > > > > > > > > > > <asp:DataList ID="datalist1" Runat='server' > > > > > > > > > > <ItemTemplate> > > > > > > > > > <asp:Label ID="Label1" Runat="server"></asp:Label>" > > > > > > > > > </ItemTemplate> > > > > > > > > > </asp:DataList> > > > > > > > > > > > > > > > > > > -- > > > > > > > > > HTH, > > > > > > > > > Phillip Williams > > > > > > > > > http://www.societopia.net > > > > > > > > > http://www.webswapp.com > > > > > > > > > > > > > > > > > > > > > > > > > > > "Erik" wrote: > > > > > > > > > > > > > > > > > > > Hi Phillip, > > > > > > > > > > The error is still occurring in > > > > > > > > > > Dim myLabel As Label = e.Item.FindControl("Label1") > > > > > > > > > > AddHandler myLabel.DataBinding, AddressOf BindParentLabelColumn > > > > > > > > > > with the addition below. The ID for the item is Nothing. I can't figure > > > > > > > > > > out what the control 'Label1' refers to since the controls are being created > > > > > > > > > > for the DataList. I apologize for my confusion, but this is new territory > > > > > > > > > > for me again. > > > > > > > > > > Thanks, Erik > > > > > > > > > > > > > > > > > > > > "Phillip Williams" wrote: > > > > > > > > > > > > > > > > > > > > > Correction; the condition should be: > > > > > > > > > > > > > > > > > > > > > > If e.Item.ItemType = ListItemType.Item Or e.Item.ItemType = > > > > > > > > > > > ListItemType.AlternatingItem Then > > > > > > > > > > > '.... > > > > > > > > > > > End IF > > > > > > > > > > > > > > > > > > > > > > "Phillip Williams" wrote: > > > > > > > > > > > > > > > > > > > > > > > Hi Erik, > > > > > > > > > > > > > > > > > > > > > > > > Yes, of course. I exptected you to fill in those tiny details :-) but here > > > > > > > > > > > > is a checked code: > > > > > > > > > > > > > > > > > > > > > > > > Private Sub DataList1_ItemCreated(ByVal sender As Object, ByVal e As > > > > > > > > > > > > DataListItemEventArgs) Handles datalist1.ItemCreated > > > > > > > > > > > > If e.Item.ItemType = ListItemType.Item And e.Item.ItemType = > > > > > > > > > > > > ListItemType.AlternatingItem Then > > > > > > > > > > > > Dim myLabel As Label = e.Item.FindControl("Label1") > > > > > > > > > > > > If Not myLabel Is Nothing Then > > > > > > > > > > > > 'this step wires up the label databinding event to a method > > > > > > > > > > > > AddHandler myLabel.DataBinding, AddressOf > > > > > > > > > > > > BindParentLabelColumn > > > > > > > > > > > > End If > > > > > > > > > > > > End If > > > > > > > > > > > > End Sub > > > > > > > > > > > > > > > > > > > > > > > > -- > > > > > > > > > > > > HTH, > > > > > > > > > > > > Phillip Williams > > > > > > > > > > > > http://www.societopia.net > > > > > > > > > > > > http://www.webswapp.com > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > "Erik" wrote: > > > > > > > > > > > > > > > > > > > > > > > > > Hi Phillip, > > > > > > > > > > > > > It appears the following is causing the error, with an itemtype = 'header'. > > > > > > > > > > > > > Should there be code added to verify the itemtype = 'item'. Thanks, Erik > > > > > > > > > > > > > > > > > > > > > > > > > > Private Sub dlstParent1_ItemCreated(ByVal sender As Object, ByVal e As > > > > > > > > > > > > > DataListItemEventArgs) Handles dlstParent1.ItemCreated > > > > > > > > > > > > > Dim myLabel As Label = e.Item.FindControl("Label1") > > > > > > > > > > > > > 'this step wires up the label databinding event to a method > > > > > > > > > > > > > AddHandler myLabel.DataBinding, AddressOf BindParentLabelColumn > > > > > > > > > > > > > End Sub > > > > > > > > > > > > > > > > > > > > > > > > > > "Phillip Williams" wrote: > > > > > > > > > > > > > > > > > > > > > > > > > > > Hi Erik, > > > > > > > > > > > > > > > > > > > > > > > > > > > > Using VS.Net debugger, set up break points within the methods that are > > > > > > > > > > > > > > triggered upon databinding (of both the datalist and the label) and step > > > > > > > > > > > > > > through them. Somewhere in the code that you did not post, you will find the > > > > > > > > > > > > > > line that threw that exception. > > > > > > > > > > > > > > -- > > > > > > > > > > > > > > HTH, > > > > > > > > > > > > > > Phillip Williams > > > > > > > > > > > > > > http://www.societopia.net > > > > > > > > > > > > > > http://www.webswapp.com > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > "Erik" wrote: > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Hi Phillip, > > > > > > > > > > > > > > > Good to hear from you also. > > > > > > > > > > > > > > > I am encountering an error (Object reference not set to an instance of an > > > > > > > > > > > > > > > object.) on line dlstParent1.DataBind after populating the Parent_Data_Table > > > > > > > > > > > > > > > with the SQL string defined from the user's parameter selection. Do I have > > > > > > > > > > > > > > > some redundant code which is causing a conflict? > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > dlstParent1.HeaderTemplate = > > > > > > > > > > > > > > > New DatalistParentLabelColumn(ListItemType.Header) > > > > > > > > > > > > > > > dlstParent1.ItemTemplate = > > > > > > > > > > > > > > > New DatalistParentLabelColumn(ListItemType.Item) > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Try > > > > > > > > > > > > > > > dvwSelect = New DataView(Parent_Data_Table(sCmd)) > > > > > > > > > > > > > > > If dvwSelect.Table.Rows.Count <> 0 Then > > > > > > > > > > > > > > > dlstParent1.DataSource = dvwSelect > > > > > > > > > > > > > > > dlstParent1.DataBind() > > > > > > > > > > > > > > > Else > > > > > > > > > > > > > > > Session("DataList_ParentDetailControls") = Nothing > > > > > > > > > > > > > > > pnlDetail.Visible = False > > > > > > > > > > > > > > > End If Good morning Erik,
Yes you are right on both counts; I missed uploading the source code therefore you only found the old demo's source code; and the second one (namely repeating the CreatTable method) was a typo on my behalf. I guess I was too much engaged in watching the elections results on TV and listening to the speech of our new Prime Minister that I was not fully paying attention when I uploaded the demo. I corrected it now. Show quoteHide quote "Erik" wrote: > Good Morning Phillip, > I was unable to see in your code where imgBtn.ImageUrl is assigned to > left.gif. Would you please point out in which function / sub the assignment > takes place? > Another question I had was calling the 'CreateTable' function twice in > Page_Init. Isn't datagrid1.DataSource = CreateTable() sufficient to create > the table for databinding? > Thanks, Erik > "Phillip Williams" wrote: > > > Hi Erik, > > > > You are quite welcome. To be able to refer to the buttons you need to give > > them IDs (I noticed that you used the commandName; while I would prefer to > > use the CommandArgument). I modified the original demo accordingly: > > http://www.societopia.net/samples/DataGrid_DynamicallyCreatedColumns.aspx > > > > As for formatting a number as currency you can use the DataFormatString > > property of the BoundColumn like this DataFormatString = "{0:C}" > > > > -- > > HTH, > > Phillip Williams > > http://www.societopia.net > > http://www.webswapp.com > > > > > > "Erik" wrote: > > > > > Good Morning Phillip, > > > I hope you enjoyed the weekend. I have everything working, and just have > > > two questions regarding the dynamically created controls (imagebutton), and > > > formatting of the databound template columns. > > > When the user clicks the 'plus' button to expand the detail information, the > > > button originally was updated to a 'minus' button. Below is the adapted code > > > for the dynamically created controls: > > > btnDetails = > > > CType(DataGrid1.Items(e.Item.ItemIndex).FindControl(e.CommandName), > > > ImageButton) > > > btnDetails = CType(e.Item.FindControl(e.CommandName.ToString), ImageButton) > > > If Not (btnDetails Is Nothing) Then > > > btnDetails.ImageUrl = "images/minus.gif" > > > Else > > > lblErrorMsg.Text = "Control " & e.CommandName.ToString & " not found." > > > End If > > > The control is not being found, and I can't find the issue with the code. > > > Next, I was wondering if there is a way to format decimal values for the > > > databound template columns. I have been able to accomplish some formatting > > > through the stylesheet, but can't figure out how to explicitly define some > > > columns value to display as currency (in Sub DataGrid1_DataBinding1). For > > > example, if dc.ColumnName = "Price" then display the value as currency. > > > Thank you again for your help. You have again provided wonderful > > > instruction and patience. > > > Erik > > > > > > > > > "Erik" wrote: > > > > > > > Hi Phillip, > > > > I have your example working locally, and am working on making it data-driven. > > > > Thanks, > > > > Erik > > > > > > > > "Phillip Williams" wrote: > > > > > > > > > Hi Erik, > > > > > > > > > > Can you post the code. (I know this page is getting pretty long, so you > > > > > might want to chop off the history out of it) > > > > > > > > > > Also, have you looked at the demo using the datagrid that I posted. It > > > > > might prove easier in getting a tidy layout. > > > > > -- > > > > > HTH, > > > > > Phillip Williams > > > > > http://www.societopia.net > > > > > http://www.webswapp.com > > > > > > > > > > > > > > > "Erik" wrote: > > > > > > > > > > > Good Morning Phillip, > > > > > > Thanks you for the instruction. I have been working through the code, and > > > > > > can't figure out an exception I am getting on line Dim drv As DataRowView = > > > > > > e.Item.DataItem() in dlstParent1_ItemDataBound. e is Nothing. > > > > > > Thanks, Erik > > > > > > "Phillip Williams" wrote: > > > > > > > > > > > > > I managed to put a concept demo that combines the techniques we referred to > > > > > > > below: 1) creating templates dynamically, and 2) creating controls > > > > > > > dynamically, based on an undetermined number of columns in a datatable. I > > > > > > > used here the datagrid instead of the datalist. > > > > > > > > > > > > > > http://www.societopia.net/Samples/DataGrid_DynamicallyCreatedColumns.aspx > > > > > > > > > > > > > > -- > > > > > > > HTH, > > > > > > > Phillip Williams > > > > > > > http://www.societopia.net > > > > > > > http://www.webswapp.com > > > > > > > > > > > > > > > > > > > > > "Phillip Williams" wrote: > > > > > > > > > > > > > > > Hi Erik, > > > > > > > > > > > > > > > > We have just displayed any number of controls (instead of HTML table > > > > > > > > columns) into one label (which is inside one ItemTemplate). > > > > > > > > > > > > > > > > This was just a modification to your original code to explain to you the > > > > > > > > concept of building the controls dynamically. (Instead of concatenating > > > > > > > > markup text that you started with, you now learned that you could add the > > > > > > > > controls dynamically within the page initialization stage to maintain their > > > > > > > > functions) > > > > > > > > > > > > > > > > To reach to a full production outcome of the application that you desire, > > > > > > > > you can build on the concepts of adding dynamic controls that we achieved in > > > > > > > > this code by refining the way you place the controls. > > > > > > > > > > > > > > > > For example, instead of using one label you can build a Table within the > > > > > > > > DataListItem. You can start by trying a simple markup like this: > > > > > > > > > > > > > > > > <asp:DataList ID="datalist1" Runat='server' CssClass="Container"> > > > > > > > > <ItemTemplate> > > > > > > > > <%--leave it empty to be populated programmatically based on # of > > > > > > > > columns--%> > > > > > > > > </ItemTemplate> > > > > > > > > </asp:DataList> > > > > > > > > > > > > > > > > And then move the code where you created the buttons within the stage of > > > > > > > > processing the DataList.ItemDataBound event like this: > > > > > > > > > > > > > > > > Private Sub DataList1_ItemDataBound(ByVal sender As Object, ByVal e As > > > > > > > > DataListItemEventArgs) Handles datalist1.ItemDataBound > > > > > > > > Dim drv As DataRowView = e.Item.DataItem() > > > > > > > > Dim dt As DataTable = drv.Row.Table > > > > > > > > Dim dc As DataColumn > > > > > > > > Dim sColumnValue As String > > > > > > > > Dim sColumnName As String > > > > > > > > 'each row would be formatted as a table that contains one row and as > > > > > > > > many cells as there > > > > > > > > 'are columns on the datatable > > > > > > > > Dim t As New Table > > > > > > > > e.Item.Controls.Add(t) 'add the table to the datalist row > > > > > > > > Dim r As New TableRow > > > > > > > > t.Rows.Add(r) > > > > > > > > > > > > > > > > For Each dc In dt.Columns > > > > > > > > Dim c As New TableCell > > > > > > > > r.Cells.Add(c) > > > > > > > > 'you have to add the imagebutton control as a control object to > > > > > > > > the > > > > > > > > 'controls collection of the label so that it would be rendered > > > > > > > > by the > > > > > > > > 'asp.net engine as a server control > > > > > > > > Dim btnImg As New ImageButton > > > > > > > > sColumnName = dc.ColumnName > > > > > > > > sColumnValue = drv(sColumnName) > > > > > > > > btnImg.ID = "Expand" + sColumnName > > > > > > > > btnImg.CommandName = "Select" + sColumnName > > > > > > > > btnImg.ImageUrl = "images/plus.gif" > > > > > > > > c.Controls.Add(btnImg) > > > > > > > > 'add the description beside the image button also as a label > > > > > > > > control > > > > > > > > 'to the original label's controls collection > > > > > > > > Dim UrlLabel As New Label > > > > > > > > UrlLabel.Text = sColumnValue > > > > > > > > c.Controls.Add(UrlLabel) > > > > > > > > Next > > > > > > > > > > > > > > > > End Sub > > > > > > > > > > > > > > > > Once you get the hang of this you might try a one-more step complex > > > > > > > > approach: to dynamically create the ItemTemplates as in this sample: > > > > > > > > http://msdn.microsoft.com/library/default.asp?url=/library/en-us/vbcon/html/vbtskcreatingwebservercontroltemplatesdynamically.asp > > > > > > > > > > > > > > > > If you still cannot get it to work, let me know and I might put a demo of it > > > > > > > > on my website. > > > > > > > > -- > > > > > > > > HTH, > > > > > > > > Phillip Williams > > > > > > > > http://www.societopia.net > > > > > > > > http://www.webswapp.com > > > > > > > > > > > > > > > > > > > > > > > > "Erik" wrote: > > > > > > > > > > > > > > > > > Is there a way I can define the ItemTemplate labels dynamically in code? The > > > > > > > > > number and definition of columns displayed is selected by the user. > > > > > > > > > Thanks, Erik > > > > > > > > > "Phillip Williams" wrote: > > > > > > > > > > > > > > > > > > > Hi Erik, > > > > > > > > > > > > > > > > > > > > That's alright. Label1 is the id of the label that I placed within the > > > > > > > > > > DataList markup. You have to give the label an Id to be able to identify it > > > > > > > > > > using the FindControl method in the Codebehind. > > > > > > > > > > > > > > > > > > > > <asp:DataList ID="datalist1" Runat='server' > > > > > > > > > > > <ItemTemplate> > > > > > > > > > > <asp:Label ID="Label1" Runat="server"></asp:Label>" > > > > > > > > > > </ItemTemplate> > > > > > > > > > > </asp:DataList> > > > > > > > > > > > > > > > > > > > > -- > > > > > > > > > > HTH, > > > > > > > > > > Phillip Williams > > > > > > > > > > http://www.societopia.net > > > > > > > > > > http://www.webswapp.com > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > "Erik" wrote: > > > > > > > > > > > > > > > > > > > > > Hi Phillip, > > > > > > > > > > > The error is still occurring in > > > > > > > > > > > Dim myLabel As Label = e.Item.FindControl("Label1") > > > > > > > > > > > AddHandler myLabel.DataBinding, AddressOf BindParentLabelColumn > > > > > > > > > > > with the addition below. The ID for the item is Nothing. I can't figure > > > > > > > > > > > out what the control 'Label1' refers to since the controls are being created > > > > > > > > > > > for the DataList. I apologize for my confusion, but this is new territory > > > > > > > > > > > for me again. > > > > > > > > > > > Thanks, Erik > > > > > > > > > > > > > > > > > > > > > > "Phillip Williams" wrote: > > > > > > > > > > > > > > > > > > > > > > > Correction; the condition should be: > > > > > > > > > > > > > > > > > > > > > > > > If e.Item.ItemType = ListItemType.Item Or e.Item.ItemType = > > > > > > > > > > > > ListItemType.AlternatingItem Then > > > > > > > > > > > > '.... > > > > > > > > > > > > End IF > > > > > > > > > > > > > > > > > > > > > > > > "Phillip Williams" wrote: > > > > > > > > > > > > > > > > > > > > > > > > > Hi Erik, > > > > > > > > > > > > > > > > > > > > > > > > > > Yes, of course. I exptected you to fill in those tiny details :-) but here > > > > > > > > > > > > > is a checked code: > > > > > > > > > > > > > > > > > > > > > > > > > > Private Sub DataList1_ItemCreated(ByVal sender As Object, ByVal e As > > > > > > > > > > > > > DataListItemEventArgs) Handles datalist1.ItemCreated > > > > > > > > > > > > > If e.Item.ItemType = ListItemType.Item And e.Item.ItemType = > > > > > > > > > > > > > ListItemType.AlternatingItem Then > > > > > > > > > > > > > Dim myLabel As Label = e.Item.FindControl("Label1") > > > > > > > > > > > > > If Not myLabel Is Nothing Then > > > > > > > > > > > > > 'this step wires up the label databinding event to a method > > > > > > > > > > > > > AddHandler myLabel.DataBinding, AddressOf > > > > > > > > > > > > > BindParentLabelColumn > > > > > > > > > > > > > End If > > > > > > > > > > > > > End If > > > > > > > > > > > > > End Sub > > > > > > > > > > > > > > > > > > > > > > > > > > -- > > > > > > > > > > > > > HTH, > > > > > > > > > > > > > Phillip Williams > > > > > > > > > > > > > http://www.societopia.net > > > > > > > > > > > > > http://www.webswapp.com > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > "Erik" wrote: > > > > > > > > > > > > > > > > > > > > > > > > > > > Hi Phillip, > > > > > > > > > > > > > > It appears the following is causing the error, with an itemtype = 'header'. > > > > > > > > > > > > > > Should there be code added to verify the itemtype = 'item'. Thanks, Erik > > > > > > > > > > > > > > > > > > > > > > > > > > > > Private Sub dlstParent1_ItemCreated(ByVal sender As Object, ByVal e As > > > > > > > > > > > > > > DataListItemEventArgs) Handles dlstParent1.ItemCreated > > > > > > > > > > > > > > Dim myLabel As Label = e.Item.FindControl("Label1") > > > > > > > > > > > > > > 'this step wires up the label databinding event to a method > > > > > > > > > > > > > > AddHandler myLabel.DataBinding, AddressOf BindParentLabelColumn > > > > > > > > > > > > > > End Sub > > > > > > > > > > > > > > > > > > > > > > > > > > > > "Phillip Williams" wrote: > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Hi Erik, > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Using VS.Net debugger, set up break points within the methods that are > > > > > > > > > > > > > > > triggered upon databinding (of both the datalist and the label) and step > > > > > > > > > > > > > > > through them. Somewhere in the code that you did not post, you will find the > > > > > > > > > > > > > > > line that threw that exception. > > > > > > > > > > > > > > > -- > > > > > > > > > > > > > > > HTH, > > > > > > > > > > > > > > > Phillip Williams > > > > > > > > > > > > > > > http://www.societopia.net > > > > > > > > > > > > > > > http://www.webswapp.com > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > "Erik" wrote: > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Hi Phillip, > > > > > > > > > > > > > > > > Good to hear from you also. > > > > > > > > > > > > > > > > I am encountering an error (Object reference not set to an instance of an > > > > > > > > > > > > > > > > object.) on line dlstParent1.DataBind after populating the Parent_Data_Table > > > > > > > > > > > > > > > > with the SQL string defined from the user's parameter selection. Do I have > > > > > > > > > > > > > > > > some redundant code which is causing a conflict? > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > dlstParent1.HeaderTemplate = > > > > > > > > > > > > > > > > New DatalistParentLabelColumn(ListItemType.Header) > > > > > > > > > > > > > > > > dlstParent1.ItemTemplate = > > > > > > > > > > > > > > > > New DatalistParentLabelColumn(ListItemType.Item)  
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