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Surprise with Textbox1.TextTextBox1.Text to be changed each time the dropdownlist selected index changes. It works in Windows application but surprisingly not not WebApplication web form. Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load DropDownList1.Items.Add("Australia") DropDownList1.Items.Add("Belgium") DropDownList1.Items.Add("Canada") DropDownList1.Items.Add("India") End Sub Private Sub DropDownList1_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) TextBox1.Text = DropDownList1.SelectedItem.Text End Sub Pls advise what's wrong with the code. Thank you, Rakesh hi Rakesh, use an IsPostBack check in your page_load to add items only if
its not a postback situation. Postback events are raised after your page_load method(so after you added items in your dropdownlist,which clears the selected item before the selectedIndexChanged method executes). Also your test case is not so clear, you basically keep adding the same items to your ddl in page_load which fires everytime an item is selected(and keeps adding to the already existing items in your dropdownlist, in this case australia,belgium,canada and india keep getting duplicated each time a postback occurs, unless you disabled viewstate on the dropdownlist. And if you did then i suggest you turn it back on, and use the ispostback check instead to populate the items only the first time. With viewstate disabled the selectedindex changed event wont fire. It needs viewstate enabled to know if the index has changed or not comparing oldvalue with new. With viewstate disabled it wont know what the old value was =P Have a good day, Alessandro Zifiglio Show quoteHide quote "Rakesh Parekh" <RakeshPar***@discussions.microsoft.com> ha scritto nel messaggio news:95889810-B228-489B-82CE-95952C31BD90@microsoft.com... > To my great surprise the following code is not working. I expect > TextBox1.Text to be > changed each time the dropdownlist selected index changes. It works in > Windows application but > surprisingly not not WebApplication web form. > > Private Sub Page_Load(ByVal sender As System.Object, ByVal e As > System.EventArgs) Handles MyBase.Load > DropDownList1.Items.Add("Australia") > DropDownList1.Items.Add("Belgium") > DropDownList1.Items.Add("Canada") > DropDownList1.Items.Add("India") > End Sub > > Private Sub DropDownList1_SelectedIndexChanged(ByVal sender As > System.Object, ByVal e As System.EventArgs) > TextBox1.Text = DropDownList1.SelectedItem.Text > End Sub > > Pls advise what's wrong with the code. > > Thank you, > Rakesh Dear Alessandro,
Thank you very much for your prompt response. I already checked using IsPostBack at the page_load event. It's not working. I also checked with EnableViewState=True and also with Falst. It is not working either. OK, for the moment let us forget to get the text/value of DropDown list to Textbox on selectedIndexChanged event. Even the following or any other TextBox property is working. Private Sub DropDownList1_SelectedIndexChanged() 'For ease of reading removed arguments. TextBox1.BackColor = System.Drawing.Color.Red End Sub The TextBox1 control is not at all getting affected with any property selection on SelectedIndexChanged event. This event is not able to do anything to the TextBox control. Till today I spent about three days on this "too simple code" without success and I am very frustrated. Please help me. Kind regards, Rakesh Show quoteHide quote "Alessandro Zifiglio" wrote: > hi Rakesh, use an IsPostBack check in your page_load to add items only if > its not a postback situation. > Postback events are raised after your page_load method(so after you added > items in your dropdownlist,which clears the selected item before the > selectedIndexChanged method executes). > > Also your test case is not so clear, you basically keep adding the same > items to your ddl in page_load which fires everytime an item is selected(and > keeps adding to the already existing items in your dropdownlist, in this > case australia,belgium,canada and india keep getting duplicated each time a > postback occurs, unless you disabled viewstate on the dropdownlist. And if > you did then i suggest you turn it back on, and use the ispostback check > instead to populate the items only the first time. With viewstate disabled > the selectedindex changed event wont fire. It needs viewstate enabled to > know if the index has changed or not comparing oldvalue with new. With > viewstate disabled it wont know what the old value was =P > Have a good day, > Alessandro Zifiglio > > "Rakesh Parekh" <RakeshPar***@discussions.microsoft.com> ha scritto nel > messaggio news:95889810-B228-489B-82CE-95952C31BD90@microsoft.com... > > To my great surprise the following code is not working. I expect > > TextBox1.Text to be > > changed each time the dropdownlist selected index changes. It works in > > Windows application but > > surprisingly not not WebApplication web form. > > > > Private Sub Page_Load(ByVal sender As System.Object, ByVal e As > > System.EventArgs) Handles MyBase.Load > > DropDownList1.Items.Add("Australia") > > DropDownList1.Items.Add("Belgium") > > DropDownList1.Items.Add("Canada") > > DropDownList1.Items.Add("India") > > End Sub > > > > Private Sub DropDownList1_SelectedIndexChanged(ByVal sender As > > System.Object, ByVal e As System.EventArgs) > > TextBox1.Text = DropDownList1.SelectedItem.Text > > End Sub > > > > Pls advise what's wrong with the code. > > > > Thank you, > > Rakesh > > > Rakesh, Seems like the event is not firing at all, verify this. It might be
the way you hooked up the event, probably done it wrongly. looking at your code and since its a private method it does not seem like you hooked it up via declarative code. So you are missing the implements parts : FOllowing is your Event in your codebehind : Private Sub DropDownList1_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) TextBox1.Text = DropDownList1.SelectedItem.Text End Sub It should be : Private Sub DropDownList1_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles DropDownList1.SelectedIndexChanged TextBox1.Text = DropDownList1.SelectedItem.Text End Sub Note the extra parts you are missing in your method -->> Handles DropDownList1.SelectedIndexChanged This is what binds the SelectedIndexChanged method to DropDownList1, without this your event will fire blank coz when your code runs the dropdownlist wont know what method is going to handle its SelectedIndexChanged event. Normally this code is automatically added for you by the IDE. Now it should be working. Have a good day, Alessandro Zifiglio Show quoteHide quote "Rakesh Parekh" <RakeshPar***@discussions.microsoft.com> ha scritto nel messaggio news:F5E1B248-1C9B-4966-B2B5-F9E6766ADAB9@microsoft.com... > Dear Alessandro, > > Thank you very much for your prompt response. I already checked > using IsPostBack at the page_load event. It's not working. I also checked > with EnableViewState=True and also with Falst. It is not working either. > OK, > for > the moment let us forget to get the text/value of DropDown list to Textbox > on > selectedIndexChanged event. > > Even the following or any other TextBox property is working. > > Private Sub DropDownList1_SelectedIndexChanged() 'For ease of reading > removed arguments. > TextBox1.BackColor = System.Drawing.Color.Red > End Sub > > The TextBox1 control is not at all getting affected with any property > selection > on SelectedIndexChanged event. This event is not able to do anything to > the > TextBox > control. Till today I spent about three days on this "too simple code" > without > success and I am very frustrated. Please help me. > > Kind regards, > Rakesh > > "Alessandro Zifiglio" wrote: > >> hi Rakesh, use an IsPostBack check in your page_load to add items only >> if >> its not a postback situation. >> Postback events are raised after your page_load method(so after you added >> items in your dropdownlist,which clears the selected item before the >> selectedIndexChanged method executes). >> >> Also your test case is not so clear, you basically keep adding the same >> items to your ddl in page_load which fires everytime an item is >> selected(and >> keeps adding to the already existing items in your dropdownlist, in this >> case australia,belgium,canada and india keep getting duplicated each time >> a >> postback occurs, unless you disabled viewstate on the dropdownlist. And >> if >> you did then i suggest you turn it back on, and use the ispostback check >> instead to populate the items only the first time. With viewstate >> disabled >> the selectedindex changed event wont fire. It needs viewstate enabled to >> know if the index has changed or not comparing oldvalue with new. With >> viewstate disabled it wont know what the old value was =P >> Have a good day, >> Alessandro Zifiglio >> >> "Rakesh Parekh" <RakeshPar***@discussions.microsoft.com> ha scritto nel >> messaggio news:95889810-B228-489B-82CE-95952C31BD90@microsoft.com... >> > To my great surprise the following code is not working. I expect >> > TextBox1.Text to be >> > changed each time the dropdownlist selected index changes. It works in >> > Windows application but >> > surprisingly not not WebApplication web form. >> > >> > Private Sub Page_Load(ByVal sender As System.Object, ByVal e As >> > System.EventArgs) Handles MyBase.Load >> > DropDownList1.Items.Add("Australia") >> > DropDownList1.Items.Add("Belgium") >> > DropDownList1.Items.Add("Canada") >> > DropDownList1.Items.Add("India") >> > End Sub >> > >> > Private Sub DropDownList1_SelectedIndexChanged(ByVal sender As >> > System.Object, ByVal e As System.EventArgs) >> > TextBox1.Text = DropDownList1.SelectedItem.Text >> > End Sub >> > >> > Pls advise what's wrong with the code. >> > >> > Thank you, >> > Rakesh >> >> >> Hi
Have you made sure that AutoPostBack is set to True on your DropDownList? Also wrap your page_load code like this (sorry, c#) if (!Page.IsPostBack) { DropDownList1.Items.Add("Australia"); DropDownList1.Items.Add("Belgium"); DropDownList1.Items.Add("Canada"); DropDownList1.Items.Add("India") ; } - Richard Alessandro, the handles selectedIndexchanged is automatically added
by IDE so that was not the problem. Thank you both Alessandro & Richard. The problem was with AutoPostback which is by default false. I turned it true and it works. The viewState is also required to be true. But now with both these properties to be true I am put in another problem surely because of them. If not IsPostBack then I populate the dropdownlist with a commandtext query to get only DISTINCT country names. It populates the dropdown list but the values filled in twice though I use distinct in query. Means, the dropdownlist shows values as under when I run the page. Australia Belgium Canada India Australia Belgium Canada India Why it fills the values twice. As per me the query runs perfect but it is because of viewstate or autopost back property it fills value twice. I tried all alternatives without success. Can you pls help. Kind regards, Rakesh Show quoteHide quote "groovyghoul" wrote: > Hi > > Have you made sure that AutoPostBack is set to True on your > DropDownList? Also wrap your page_load code like this (sorry, c#) > > if (!Page.IsPostBack) > { > DropDownList1.Items.Add("Australia"); > DropDownList1.Items.Add("Belgium"); > DropDownList1.Items.Add("Canada"); > DropDownList1.Items.Add("India") ; > } > > - Richard > > Hi Rakesh
Can you confirm that you have wrapped the code the populates the dropdownlist with a check for IsPostBack. If you do not, then you will populate everytime a postback is performed. Also, just for kicks, make sure that you are not populating that ddl anywhere else in your code. If you want, why don't you post the code block that you are using to populate and we'll take a quick peek at it. - Richard 
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