ASP.NET Life Cycle and Best Practices - Steps 7 Through 10
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7. Prerender the Objects
The point at which the objects are prerendered is the last time changes to the objects can be saved or persisted to viewstate. This makes the PreRender step a good place to make final modifications, such as changing properties of controls or changing Control Tree structure, without having to worry about ASP.NET making changes to objects based off of database calls or viewstate updates. After the PreRender phase those changes to objects are locked in and can no longer be saved to the page viewstate. The PreRender step can be overridden using OnPreRender.
8. ViewState Saved
The viewstate is saved after all changes to the page objects have occurred. Object state data is persisted in the hidden <input> object and this is also where object state data is prepared to be rendered to HTML. At the SaveViewState event, values can be saved to the ViewState object, but changes to page controls are not. You can override this step by using SaveViewState.
9. Render To HTML
The Render event commences the building of the page by assembling the HTML for output to the browser. During the Render event, the page calls on the objects to render them into HTML. The page then collects the HTML for delivery. When the Render event is overridden, the developer can write custom HTML to the browser that nullifies all the HTML the page has created thus far. The Render method takes an HtmlTextWriter object as a parameter and uses that to output HTML to be streamed to the browser. Changes can still be made at this point, but they are reflected to the client only.
10. Disposal
After the page's HTML is rendered, the objects are disposed of. During the Dispose event, you should destroy any objects or references you have created in building the page. At this point, all processing has occurred and it is safe to dispose of any remaining objects, including the Page object. You can override Dispose, as well as Render by setting the appropriate selection in the object parameter.
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