ASP .Net Page Life Cycle Events

ASP .Net Page Life Cycle Events:

PreInit:

You can:

• Check for the IsPostBack property to determine whether this is the first time the page is being processed.
• Create or recreate dynamic controls.
• Set master page dynamically.
• Set the Theme property dynamically.
• Read or set profile property values.

If Request is postback:

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

Init:

• In the Init event of the individual controls occurs first, later the Init event of the Page takes place.
• This event is used to initialize control properties.

InitComplete:

• Tracking of the ViewState is turned on in this event.
• Any changes made to the ViewState in this event are persisted even after the next postback.

PreLoad:

• This event processes the postback data that is included with the request.

Load:

• In this event the Page object calls the OnLoad method on the Page object itself, later the OnLoad method of the controls is called.
• Thus Load event of the individual controls occurs after the Load event of the page.

ControlEvents:

• This event is used to handle specific control events such as a Button control’s Click event or a TextBoxcontrol’s TextChanged event.

In case of postback:

• If the page contains validator controls, the Page.IsValid property and the validation of the controls takes place before the firing of individual control events.

LoadComplete:

• This event occurs after the event handling stage.
• This event is used for tasks such as loading all other controls on the page.

PreRender:

• In this event the PreRender event of the page is called first and later for the child control.

Usage:

• This method is used to make final changes to the controls on the page like assigning the DataSourceId and calling the DataBind method.

PreRenderComplete:

• This event is raised after each control's PreRender property is completed.

SaveStateComplete:

• This is raised after the control state and view state have been saved for the page and for all controls.

RenderComplete:

• The page object calls this method on each control which is present on the page.
• This method writes the control’s markup to send it to the browser.

Unload:

• This event is raised for each control and then for the Page object.

Usage:

• Use this event in controls for final cleanup work, such as closing open database connections, closing open files, etc.