Page life cycle
The .aspx mechanism is most detailed HttpHandler in ASP.NET .
this HttpHandler fires events along its Life cycle so it is possible to write code between the creation steps of the page.
The Life cycle of The .aspx, depends on whether the page is requested for the first time or it is a
postback.
The events:
PreInit
This event is the beginning of the page life cycle. Every page controls are initialized and the properties are set according to aspx source code.
- Check the IsPostBack property to determine whether this is the first time the page is being processed.
- Change or set Master page, Themes.
- Creates or re-creates dynamic controls.
- Reads or sets Profile property values.
Init
First, the Init event for the Page object occurs, then Init event occurs for each control on the Page. Viewstate information is not available at this stage.
- Controls have been initialized.
- Theme skins applied if any.
- Initialize control properties.
LoadViewState when PostBack is true
During this phase, the view state of the control posted by the client is reloaded into the new instance of the control.
LoadPostData when PostBack is true
During this phase, the server searches any data corresponding to the control that is loaded in the data posted by the client.
InitComplete
This event is used to processing tasks that require all initialization be complete.
PreLoad
This event is used before Perform any processing that should occur before Load. Use this event if you need to perform processing on your page or control before the Load 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.
Load
Set properties in controls and establish database connection
Control Events
These are control specific events such as – Button Click, DropDownIndexChanged etc.
Load Complete
This event is used for performing those tasks which require load has been completed.
RaisePostBackEvent when PostBack is true
During this phase, the server searches any data corresponding to the control that is loaded in the data posted by the client.
PreRender
In this event page insures that all child controls are created. Page calls EnsureChildControls for all controls, including itself. Every controls whose datasource/databind property is set calls for its databind method.
SaveStateComplete
This event occurs after viewstate encoded and saved for the page and for all controls.
Render
Every ASP.NET control has render method and the page instance calls this method to output the control’s markup, after this event any changes to the page or controls are ignored.
Unload
Unload event used to do cleanup task like closing the database connections, closing of the open files, completing logging or other requested tasks. Unload events occurs for each control on page control tree first and after that page.
