Our project has inherited some composite controls that we can't change. One of these composite controls contains a dropdownlist that we'd like to trigger an asyncpostback that fires an update panel.

 We can make the dropdownlist AutoPostBack but we can't make it work asynchronously. I've tried a number of things including using the unique client ID without success:

e.g.

	<triggers>
		<ajax:AsyncPostBackTrigger ControlID="compositeControl$ctl01" EventName="OnSelectedIndexChanged"></ajax:AsyncPostBackTrigger>
	</triggers>
</ajax:UpdatePanel>

 Any ideas?

 

Try to change your codes as the following.It should work fine.
<triggers>
<ajax:AsyncPostBackTrigger ControlID="compositeControlID" EventName="SelectedIndexChanged"></ajax:AsyncPostBackTrigger>
</triggers>
</ajax:UpdatePanel>
If you still have any problem,I suggest you to download the latest Ajax Beta 2 and Futures November CTP to install in your PC.
Wish the above can give you some helps.

Thanks Jasson,

That wouldn't work because nothing is posted back with the compositeControlID - it wouldn't get picked up against the list of _asyncPostBackControlIDs. Finding this out led to the solution though:

 My subcontrol didn't have an ID set explicitly...

 _listBox.Id = "someId";

 Now this works:

<triggers>
<ajax:AsyncPostBackTrigger ControlID="compositeControlID$someId" EventName="SelectedIndexChanged"></ajax:AsyncPostBackTrigger>
</triggers>
</ajax:UpdatePanel>