Wednesday, September 1, 2010

Page Life Cycle Events in ASP.NET

EventDescription
PreInitThis is the first real event you might handle for a page. You typically
use this event only if you need to dynamically (from code) set
values such as master page or theme.
This event is also useful when you are working with dynamically
created controls for a page. You want to create the controls inside
this event.
InitThis event fires after each control has been initialized. You can use
this event to change initialization values for controls.
InitCompleteRaised once all initializations of the page and its controls have
been completed.
PreLoadThis event fires before view state has been loaded for the page
and its controls and before PostBack processing. This event is useful
when you need to write code after the page is initialized but
before the view state has been wired back up to the controls.
LoadThe page is stable at this time; it has been initialized and its state
has been reconstructed. Code inside the page load event typically
checks for PostBack and then sets control properties appropriately.
The page’s load event is called first. Then, the load event for each
child control is called in turn (and their child controls, if any). This
is important to know if you are writing your own user or custom
controls.
Control (PostBack) event(s)ASP.NET now calls any events on the page or its controls thatcaused the PostBack to occur. This might be a button’s click event,for example.
LoadCompleteAt this point all controls are loaded. If you need to do additional
processing at this time you can do so here.
PreRenderAllows final changes to the page or its control. This event takes place after all regular PostBack events have taken place. This event takes place before saving ViewState, so any changes made here are saved.
SaveStateCompletePrior to this event the view state for the page and its controls is set. Any changes to the page’s controls at this point or beyond are ignored. This is useful if you need to write processing that requires the view state to be set.
RenderThe Render method generates the client-side HTML, Dynamic Hypertext Markup Language (DHTML), and script that are necessary to properly display a control at the browser. This method is useful if you are writing your own custom control. You override this method to control output for the control.
UnLoadThis event is used for cleanup code. You use it to release any managed resources in this stage. Managed resources are resources that are handled by the runtime, such as instances of classes created by the .NET common language runtime.

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