Ajax Triggers for DropDownList don't fire

22 Dec 2006 9:28 AM

Troy Donavan

I'm trying to get a partial page (Ajax style) update when the selection of a
DropDownList changes. I'm not having much luck. I will continue plugging
away at the sample applications in hopes of finding some hints, but
meanwhile, if someone could point out to me what I am doing wrong, I would
appreciate it. Here is a page with three controls on it. They are for
selection of Country, State and Locality. The idea is that when one chooses
the country, the possible selections for state (region) would then update and
similarly for localities.

Let me know if you can spot my problem. Here is the code:

<%@ Page Language="VB" AutoEventWireup="true" CodeFile="Default.aspx.vb"
Inherits="_Default" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN"
"http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title>Untitled Page</title>
</head>
<body>
    <form id="form1" runat="server">
        <asp:ScriptManager ID="ScriptManager1" runat="server" />
        <div>

            <asp:UpdatePanel ID="UPCountry" runat="server">
            <ContentTemplate>

                <asp:DropDownList ID="DDCountry" runat="server"
style="z-index: 100; left: 500px; position: absolute; top: 100px; width:
200px" OnLoad="DDCountry_Load">
                </asp:DropDownList>

                <asp:DropDownList style="Z-INDEX: 100; LEFT: 500px; WIDTH:
200px; POSITION: absolute; TOP: 130px" id="DDState" runat="server"
OnLoad="DDState_Load">
                </asp:DropDownList>

                <asp:DropDownList style="Z-INDEX: 100; LEFT: 500px; WIDTH:
200px; POSITION: absolute; TOP: 160px" id="DDLocality" runat="server"
OnLoad="DDLocality_Load">
                </asp:DropDownList>
            </ContentTemplate>
            <triggers>
                <asp:AsyncPostBackTrigger ControlID="DDState"
EventName="TextChanged"></asp:AsyncPostBackTrigger>
                <asp:AsyncPostBackTrigger ControlID="DDCountry"
EventName="TextChanged"></asp:AsyncPostBackTrigger>
            </triggers>
            </asp:UpdatePanel>

        </div>
    </form>
</body>
</html>

--
Troy Donavan

24 Dec 2006 5:46 AM

technoGirl

Troy,

Shouldn't you be using OnSelectedIndexChanged =
DDCountry_SelectedIndexChanged for your drop downs??? Since you want a
ajax style functionality??
Tina

Troy Donavan wrote:
Show quoteHide quote

> I'm trying to get a partial page (Ajax style) update when the selection of a
> DropDownList changes. I'm not having much luck. I will continue plugging
> away at the sample applications in hopes of finding some hints, but
> meanwhile, if someone could point out to me what I am doing wrong, I would
> appreciate it. Here is a page with three controls on it. They are for
> selection of Country, State and Locality. The idea is that when one chooses
> the country, the possible selections for state (region) would then update and
> similarly for localities.
>
> Let me know if you can spot my problem. Here is the code:
>
>
> <%@ Page Language="VB" AutoEventWireup="true" CodeFile="Default.aspx.vb"
> Inherits="_Default" %>
>
> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN"
> "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
> <html xmlns="http://www.w3.org/1999/xhtml">
> <head runat="server">
>     <title>Untitled Page</title>
> </head>
> <body>
>     <form id="form1" runat="server">
>         <asp:ScriptManager ID="ScriptManager1" runat="server" />
>         <div>
>
>             <asp:UpdatePanel ID="UPCountry" runat="server">
>             <ContentTemplate>
>
>                 <asp:DropDownList ID="DDCountry" runat="server"
> style="z-index: 100; left: 500px; position: absolute; top: 100px; width:
> 200px" OnLoad="DDCountry_Load">
>                 </asp:DropDownList>
>
>                 <asp:DropDownList style="Z-INDEX: 100; LEFT: 500px; WIDTH:
> 200px; POSITION: absolute; TOP: 130px" id="DDState" runat="server"
> OnLoad="DDState_Load">
>                 </asp:DropDownList>
>
>                 <asp:DropDownList style="Z-INDEX: 100; LEFT: 500px; WIDTH:
> 200px; POSITION: absolute; TOP: 160px" id="DDLocality" runat="server"
> OnLoad="DDLocality_Load">
>                 </asp:DropDownList>
>             </ContentTemplate>
>             <triggers>
>                 <asp:AsyncPostBackTrigger ControlID="DDState"
> EventName="TextChanged"></asp:AsyncPostBackTrigger>
>                 <asp:AsyncPostBackTrigger ControlID="DDCountry"
> EventName="TextChanged"></asp:AsyncPostBackTrigger>
>             </triggers>
>             </asp:UpdatePanel>
>
>         </div>
>     </form>
> </body>
> </html>
>
>
> --
> Troy Donavan

25 Dec 2006 9:09 AM

Walter Wang [MSFT]

Hi Troy,

As Tina pointed out, if you want to update second DropDownList when the
first one changes, you need to handle the first one's SelectedIndexChanged
event instead of the Load event. Also you need to set the first
DropDownList's AutoPostBack to true:

            <asp:UpdatePanel ID="UPCountry" runat="server">
                <ContentTemplate>
                    <asp:DropDownList ID="DDCountry" runat="server"
Style="z-index: 100; left: 500px;
                        position: absolute; top: 100px; width: 200px"
OnLoad="DDCountry_Load"
OnSelectedIndexChanged="DDCountry_SelectedIndexChanged" AutoPostBack="true">
                        <asp:ListItem>1</asp:ListItem>
                        <asp:ListItem>2</asp:ListItem>
                    </asp:DropDownList>

    Protected Sub DDCountry_SelectedIndexChanged(ByVal sender As Object,
ByVal e As System.EventArgs)
        DDState.Items.Clear()
        Dim s As String = DDCountry.SelectedItem.Text
        For i As Integer = 1 To 2
            DDState.Items.Add(s + "_" + i.ToString())
        Next
    End Sub

Hope this helps.

Sincerely,
Walter Wang (waw***@online.microsoft.com, remove 'online.')
Microsoft Online Community Support

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27 Dec 2006 6:32 AM

Troy Donavan

>AutoPostBack="true"

What a wonderful concept!!! Thank you very much!

--
Troy Donavan

Show quoteHide quote

"Walter Wang [MSFT]" wrote:

> Hi Troy,
>
> As Tina pointed out, if you want to update second DropDownList when the
> first one changes, you need to handle the first one's SelectedIndexChanged
> event instead of the Load event. Also you need to set the first
> DropDownList's AutoPostBack to true:
>
>             <asp:UpdatePanel ID="UPCountry" runat="server">
>                 <ContentTemplate>
>                     <asp:DropDownList ID="DDCountry" runat="server"
> Style="z-index: 100; left: 500px;
>                         position: absolute; top: 100px; width: 200px"
> OnLoad="DDCountry_Load"
> OnSelectedIndexChanged="DDCountry_SelectedIndexChanged" AutoPostBack="true">
>                         <asp:ListItem>1</asp:ListItem>
>                         <asp:ListItem>2</asp:ListItem>
>                     </asp:DropDownList>
>
>
>
>     Protected Sub DDCountry_SelectedIndexChanged(ByVal sender As Object,
> ByVal e As System.EventArgs)
>         DDState.Items.Clear()
>         Dim s As String = DDCountry.SelectedItem.Text
>         For i As Integer = 1 To 2
>             DDState.Items.Add(s + "_" + i.ToString())
>         Next
>     End Sub
>
>
>
> Hope this helps.
>
> Sincerely,
> Walter Wang (waw***@online.microsoft.com, remove 'online.')
> Microsoft Online Community Support
>
> ==================================================
> Get notification to my posts through email? Please refer to
> http://msdn.microsoft.com/subscriptions/managednewsgroups/default.aspx#notif
> ications. If you are using Outlook Express, please make sure you clear the
> check box "Tools/Options/Read: Get 300 headers at a time" to see your reply
> promptly.
>
> Note: The MSDN Managed Newsgroup support offering is for non-urgent issues
> where an initial response from the community or a Microsoft Support
> Engineer within 1 business day is acceptable. Please note that each follow
> up response may take approximately 2 business days as the support
> professional working with you may need further investigation to reach the
> most efficient resolution. The offering is not appropriate for situations
> that require urgent, real-time or phone-based interactions or complex
> project analysis and dump analysis issues. Issues of this nature are best
> handled working with a dedicated Microsoft Support Engineer by contacting
> Microsoft Customer Support Services (CSS) at
> http://msdn.microsoft.com/subscriptions/support/default.aspx.
> ==================================================
>
> This posting is provided "AS IS" with no warranties, and confers no rights.
>
>