I have a composite drop down calendar user control that consists of a textbox and and calendar image and a validation control. I expose a property called "TextBox" on
the usercontrol which returns a reference to
the textbox used within
the control. This is
the textbox that
the user enters
the date into.
In
the ASPX page, I have an instance of this usercontrol:
<uc1:DropDownCalendar ID="dtmDateFirstEntry" runat="server" Required="True" />
In my code
behind, I want to detect when a user has tabbed off of
the textbox and, using an UpdatePanel, referesh an appropriate message depending on
the date that was specified.
Elsewhere in
the ASPX page I have this:
<asp:UpdatePanel ID="upIntendedStay" runat="server">
<ContentTemplate>
<asp:Label ID="Label4" runat="server" Text="Update this text from server" CssClass="ErrorText"></asp:Label>
</ContentTemplate>
</asp:UpdatePanel>
Here's what I do in
the code behind:
If Not Me.IsPostBack Then
dtmDateFirstEntry.TextBox.AutoPostBack = True
Dim trigger As New AsyncPostBackTrigger
trigger.ControlID = dtmDateFirstEntry.TextBox.ClientID
trigger.EventName = "onChange"
upIntendedStay.Triggers.Add(trigger)
End If
When
the page runs and I view
the source, I see something like this:
<input id="ctl00_phPageContent_dtmDateFirstEntry_txtDate" class="DefaultTextBox" name="ctl00$phPageContent$dtmDateFirstEntry$txtDate" onchange="javascript:setTimeout('__doPostBack(\'ctl00$phPageContent$dtmDateFirstEntry$txtDate\',\'\')', 0)" onkeypress="if (WebForm_TextBoxKeyHandler(event) == false) return false;" style="width: 112px;" type="text" value="Mar-29-2010" />
<input id="ctl00_phPageContent_dtmDateFirstEntry_imgDate" name="ctl00$phPageContent$dtmDateFirstEntry$imgDate" src="images/calendar.JPG" style="border-width: 0px;" type="image" />
When I run it, I get this error:
A control with ID 'ctl00_phPageContent_dtmDateFirstEntry_txtDate' could not be found for
the trigger in UpdatePanel 'upIntendedStay'.
I didn't think that
the trigger control had to be within
the UpdatePanel. I thought that was
the whole point of adding
the trigger.
How do I refresh this update panel changes to
the text in
the date usercontrol. Next I will have to add other triggers to trigger
the refreshing of
the Update Panel from other controls scattered across
the page, so clearly all of
the trigger sources cannot be within
the UpdatePanel.
