• Check the IsPostBack property to determine whether this is the first time the page is being processed.
• Create or re-create dynamic controls.
• Set a master page dynamically.
• Set the Theme property dynamically.
• Read or set profile property values.
  Note:

  If the request is a postback, the values of the controls have not yet been restored from view state. If you set a control property at this stage, its value might be overwritten in the next event.

Before the Page instance raises this event, it loads view state for itself and all controls, and then processes any postback data included with the Request instance.

Use the OnLoad event method to set properties in controls and establish database connections.

• The Page object calls EnsureChildControls for each control and for the page.
• Each data bound control whose DataSourceID property is set calls its DataBind method. For more information, see Data Binding Events for Data-Bound Controls later in this topic.

The PreRender event occurs for each control on the page. Use the event to make final changes to the contents of the page or its controls.

Use this event perform tasks that require view state to be saved, but that do not make any changes to controls.

If you create a custom control, you typically override this method to output the control’s markup. However, if your custom control incorporates only standard ASP.NET Web server controls and no custom markup, you do not need to override the Render method. For more information, see Developing Custom ASP.NET Server Controls.

A user control (an .ascx file) automatically incorporates rendering, so you do not need to explicitly render the control in code.

For the page itself, use this event to do final cleanup work, such as closing open files and database connections, or finishing up logging or other request-specific tasks.

Note:

During the unload stage, the page and its controls have been rendered, so you cannot make further changes to the response stream. If you attempt to call a method such as the Response.Write method, the page will throw an exception.