Determining the source of a partial rendering postback

Is there a way to determine (on the server) what trigger/control/event was the source of the postback? How about something that indicates what update panel(s) will be rendered?

I see that the script manager has an IsInAsyncPostBack property, but I'm curious if there is something more specific.

UpdatePanel.IsInPartialRendering does not seem to work.

You could check the _EventTarget for a hint on what triggered the PostBack.

What would you do differently if you knew what triggered the PostBack?

You could use the ScriptManager.AsyncPostBackSourceElementID to determine the source of the asynchronous postback. In terms of what UpdatePanels will get updated, in server code I don't think there is a summary list that lists them because the Update() method can be called by any code and tracking that is difficult if not impossible(?). However, on the client you can use the pageLoaded or pageLoading events of the PageRequestManager to get information about what panels will be created, updated or deleted.

Determine what element caused the Postback when handling the endRequest event

Hi All,

I have an UpdatePanel with 2 buttons. Pressing either of them causes a Postback and the panel gets refreshed.

I'm handling the endRequest event on the client side. Is there a way to determine which of the page elements caused the Postback?

Thanks,

Uzi

Try here:

http://www.eggheadcafe.com/articles/20050609.asp

Hi,

you can determine the postback element on the client side with the PageRequestManager. Attach to the beginRequest event and you can save the postback control. More information here:

http://ajax.asp.net/docs/ClientReference/Sys.WebForms/BeginRequestEventArgsClass/default.aspx

Regards
Marc André

Here is a neat way to get it done:

In the 'BeginRequest' event handler insert the postback element to the UserContext of the WebRequest:

function BeginRequestHandler(sender, args)

{

var elemName = args.get_postBackElement().id;var request = args.get_request();

request.set_userContext(elemName);

}

Then, when the request ends, at the 'EndEvent' get the information from the Response object:

function EndRequestHandler(sender, args)

{

var response = args.get_response();

alert(response._webRequest.get_userContext());

}

Thanks,

Uzi