UpdatePanel is doing full postback when it should not

[TomK]

I have a ASP.NET 2.0 web application that was written using traditional
postbacks.
I am in the process of Ajaxifying some pages.

PROBLEM: Update panel is always causing postbacks

I have 1 test page that does partial postbacks no problem. The second page
is a legacy page that I have wrapped some controls in UpdatePanels and
followed a similar model as the working test page. Whenever the UpdatePanel
trigger is fired I keep getting full postbacks even though I have
EnablePartialRendering=true.

I know it has to be something at the page level since the test page works
fine.

Here are some sample snippets:

<asp:ScriptManager runat="server" ID="ctlScriptManager"
EnablePartialRendering="true" >
</asp:ScriptManager>
<script type="text/javascript" language="javascript">
try
{
var prm = Sys.WebForms.PageRequestManager.getInstance();
prm.add_initializeRequest(InitializeRequest);
prm.add_beginRequest(doNothing);
prm.add_pageLoading(doNothing);
prm.add_pageLoaded(doNothing);
prm.add_endRequest(EndRequest);
}catch(e)
{
//alert("There was an error setting up ScriptManager");
}

function InitializeRequest(sender, args)
{

alert('InitializeRequest');
debugger
if (prm.get_isInAsyncPostBack())
{
alert('cancelled double request');
args.set_cancel(true);
}else
{
if (!OnSubmitValidation())
{
alert('handled validation error');
args.set_cancel(true);
prm._originalDoPostBack(args._postBackElement.id,'');
}
}
}

function doNothing(sender, args)
{
}

function EndRequest(sender, args)
{
DisableOnSubmitValidation();

// TODO: handle timeout errors, and revert to fullpage postback
if (args.get_error() && args.get_response().get_timedOut())
{
prm._originalDoPostBack(args._postBackElement.id,'');
//alert('handled time out');
args.set_errorHandled(true);
}
}
</script>

THIS IS THE TRIGGER CONTROL
<aspropDownList ID="ddlCategory" alt="Category" runat="server"
Width="100%" CssClass="clsDropDown" AutoPostBack="true">

</aspropDownList>

<asp:UpdatePanel runat="server"
ID="updPnlCaseType" UpdateMode="Conditional">
<ContentTemplate>
<aspropDownList ID="ddlCaseType"
alt="Case Type" runat="server"
Width="100%" CssClass="clsDropDown"
AutoPostBack="True">
</aspropDownList>
</ContentTemplate>
<Triggers>
<asp:AsyncPostBackTrigger ControlID="ddlCategory"
EventName="SelectedIndexChanged" />
</Triggers>
</asp:UpdatePanel>

<asp:UpdatePanel runat="server" ID="updPnlLocation" UpdateMode="Conditional">
<ContentTemplate>
<table><tr>
<td class="clstd" style="width: 10%; vertical-align: top;">
<div id="divLocationLabel" runat="server">Location:</div>
</td>
<td class="clstd" style="width: 700px">
<div id="divLocation" runat="server">
<ctrllocation:location ID="LocationControlCase"
runat="server"
SelectedLocation="All">
</ctrllocation:location>
</div>
</td>
</tr></table>
</ContentTemplate>
<Triggers>
<asp:AsyncPostBackTrigger ControlID="ddlCaseType"
EventName="SelectedIndexChanged" />
<asp:AsyncPostBackTrigger ControlID="ddlCategory"
EventName="SelectedIndexChanged" />
</Triggers>
</asp:UpdatePanel>

<asp:UpdatePanel runat="server" ID="updPnlUDEFs" UpdateMode="always">
<ContentTemplate>
<ctrlUserDefinedFields:UserDefinedFields
ID="ucCaseSubmissionFields" runat="server" />
</ContentTemplate>
</asp:UpdatePanel>

Tom

 

[Harry Keck]

When you say the whole page is posting back, do you mean that it is doing the
"flicker" kind of postback where the entire page is re-rendered? If so, then
yes, you do have a problem, but I can not tell anything wrong with the code
you supplied.

If, however, you simply mean that all of your server side code is running
everytime an updatepanel updates, then that is correct behavior. When and
AJAX page posts back, all of the server side code runs just as if partial
rendering were not enabled. The only difference is that the client will only
re-paint the portions marked for update.

 

[TomK]

I see. So is the entired rendered page sent back and only the portions
belonging to update panels used? Or are only the parts from update panels
sent back to the client?

I also notice that while in a partial postback if you put a break point on
the server the client page is unresponsive until a response is received. Is
this normal? Since this does not seem to be "asynchronous" behaviour to me.