Event sequence of Grid

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yuki
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yuki asked on 24 Aug 2023, 09:59 AM | edited on 25 Aug 2023, 03:50 AM

What is the event sequence of grid OnPreRender? Will it be fired only once or every time there is a postback?

When the grid is ajaxified, will OnPreRender be fired every time when there is a postback?

I'm asking this because when postback my breakpoint in Grid OnPreRender is not hit after Page_PreRender event when the grid is ajaxified.

Thanks.

Rumen
Telerik team
commented on 28 Aug 2023, 06:42 AM

In ASP.NET Web Forms, the event sequence for a control's lifecycle, including the RadGrid control, is crucial for understanding how events are triggered and handled. Specifically, the OnPreRender event is part of this lifecycle.

The OnPreRender event occurs after the Page_Load event and before the Page_PreRender event. It is raised when the server control is about to render to the client. This event is fired during every postback and not just once during the initial page load. This means that if there is a postback, the OnPreRender event will be fired again.

If you are working with AJAX in ASP.NET Web Forms, whether using the built-in ASP.NET AJAX library (UpdatePanels) or a jQuery AJAX, the behavior can vary based on how the AJAX updates are handled.

When a control, such as the Grid is ajaxified, its lifecycle events still occur, but they might behave differently in the context of AJAX updates. In some cases, depending on the specifics of how the AJAX update is implemented, the OnPreRender event might not fire as expected during a partial postback, which could explain why your breakpoint is not being hit.

Here are a few things to consider when debugging the issue you're facing:
  • Check the RadGrid Events Life cycle and Event sequence articles:
  • Check AJAX Configuration: Ensure that the Grid is properly configured for AJAX updates.
    • If you are using RadAjaxPanel/RadAjaxManager disable the ajax by setting EnableAjax="false", check for any errors in the console and test again.
    • If you're using UpdatePanels, make sure the Grid is inside an UpdatePanel control and that triggers are set up correctly.
    • If you're using a different AJAX library, ensure that the necessary controls are being targeted for updates.
  • UpdatePanel Lifecycle: If you are using UpdatePanels, remember that controls inside an UpdatePanel still go through their lifecycle events, but the events are only triggered for the controls within the UpdatePanel, not the whole page. Make sure that your Grid is within the UpdatePanel that's being updated during the AJAX request.
  • Double-check that your breakpoint in Visual Studio is correctly set in the OnPreRender event handler of the Grid. Also, ensure that your browser's developer tools are open and capable of breaking on server-side code, especially during AJAX requests.
  • Other Event Interactions: Check if there are any other event handlers, methods, or conditions that might be affecting the normal flow of events, including during AJAX updates.
yuki
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commented on 28 Aug 2023, 06:58 AM

Hello friend, thanks for the very detailed explanation. You really help me a lot!

No answers yet. Maybe you can help?

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