ListSearchExtender and AutoPostBack

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I'm using a DropDownList control with an AJAX ListSearchExtender within an UpdatePanel. Since I added the extender, the DropDownList's events are not firing until you tab out of the control or click enter. My users need to see the changes immediately without having to tab or press enter. Is there any way to accomplish this?

Posted 15-Apr-11 5:54am

Lonnie Raffray

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Albin Abel · Answer 1 · 2011-04-15T07:08:00

Solution 1

It is not true the extender hide the events from the control. If you put a break inside your routine you may found the event handler code is running. If you want to update a control on a async postback which is not inside the update panel then look at this link http://msdn.microsoft.com/en-us/magazine/cc163354.aspx[^]

"My users need to see the changes immediately without having to tab or press enter"- How the control knows your user finished entering chars? There should be a way to tell it right...enter, tab, blur event etc.,

Posted 15-Apr-11 7:08am

Albin Abel

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Lonnie Raffray 15-Apr-11 13:11pm

Yes, the events are firing, but not until the user tabs or presses enter. I need them to fire immediately. And the controls I am updating are all in the same update panel.

Albin Abel 15-Apr-11 13:14pm

Hi Lonnie Raffray which event you are expecting to fire before enter or tab?

Lonnie Raffray 15-Apr-11 13:15pm

SelectedIndexChanged

Albin Abel 15-Apr-11 13:45pm

SelectIndexChanged supposed run after user selects something. Usually that is by hitting the enter or tab or a mouse click. Which action you want to raise that event? I mean which action ensures user selected something. If you tell that we will try to help write a custom event.

Albin Abel 15-Apr-11 13:50pm

If you want something to do when user types something you can use TextChanged event

Lonnie Raffray 15-Apr-11 13:53pm

If I use a DropDownList control in an update panel with AutoPostBack set to True, and without an extender, the page posts back and the SelectedIndexChanged event fires whenever the user selects from the list either by typing or clicking and selecting with the mouse. They do not have to press tab or enter. But with the extender attached, the page does not post back until the user presses tab or enter.

Albin Abel 15-Apr-11 14:22pm

"click" still fire the selectedindexchanged event with the extender also. Try this
<asp:UpdatePanel runat="server">
<contenttemplate>
<asp:DropDownList AutoPostBack="true" OnSelectedIndexChanged="dl_SelectChanged" ID="DropDownList1" runat="server">
<asp:ListItem Text="Item1">
<asp:ListItem Text="Item2">

<asp:ListSearchExtender ID="DropDownList1_ListSearchExtender" runat="server"
Enabled="True" TargetControlID="DropDownList1" >

then in the code behind
protected void dl_SelectChanged(object sender, EventArgs e)
{
System.Diagnostics.Debugger.Break();
}

Lonnie Raffray 15-Apr-11 16:10pm

This is my code:

<asp:DropDownList ID="DDL_ClassCode" runat="server" Width="400px" AutoPostBack=true CssClass=text9p>
<ajaxToolkit:ListSearchExtender ID="LSE_ClassCode" runat="server" TargetControlID=DDL_ClassCode IsSorted=true PromptCssClass="hiddenprompt">

The list is populated dynamically. In my code-behind page, the event handler is declared like this:

Protected Sub DDL_ClassCode_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles DDL_ClassCode.SelectedIndexChanged
End Sub

I put a break point in the event handler code and ran it in debug. It does not break until I press tab or enter.

Lonnie Raffray 15-Apr-11 16:13pm

Also, the TextChanged event does the same thing. It does not fire until I press tab or enter or otherwise select from the list. I need it to fire when typing in the list. That's the way it worked without the extender.

Albin Abel 15-Apr-11 23:08pm

Hi Lonnie Raffray, Is that is your original markup. if so it has few issues like parameters not wrapped in quotes and the elements are not closed. Anyway I have tried this...My markup
<asp:DropDownList ID="DDL_ClassCode" runat="server" Width="400px" AutoPostBack="true" >

<asp:ListSearchExtender ID="LSE_ClassCode" runat="server"
Enabled="True" TargetControlID="DDL_ClassCode" IsSorted="true">

My code behind

protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
ListItem item1 = new ListItem("Item1", "1");
ListItem item2 = new ListItem("Item2", "2");
DDL_ClassCode.Items.Add(item1);
DDL_ClassCode.Items.Add(item2);
}
DDL_ClassCode.SelectedIndexChanged += new EventHandler(DDL_ClassCode_SelectedIndexChanged);

}

protected void DDL_ClassCode_SelectedIndexChanged(object sender, EventArgs e)
{
System.Diagnostics.Debugger.Break();
}

There is no issues. The event fires when i click any item with mouse. I just wonder is there a compatibility issue between vb.net and ajax toolkit. I am using c# with .Net framework 4

Albin Abel 15-Apr-11 23:12pm

Oops this comment box just trimming the closing tags. So I understood it did on your comment as well.

Lonnie Raffray 16-Apr-11 10:07am

The only difference I see between your code and mine is the language. I have to use VB instead of C# because that is our shop standard. There must be a compatibility issue somewhere. I will have to try to find a work-around, or abandon the use of the extender in this particular case. It all works fine when not contained in an update panel. Thanks for all your help.