ASP.NET 2.0 Page LifeCycle

URL:http://www.eggheadcafe.com/articles/20051227.asp

I was searching the web for some information on the ASP.NET 2.0 Page LifeCycle to see what's new and different from ASP.NET 1.1. This chart was created by Leon Andrianarivony, and unfortunately the original URL to it is dead. So I'll start by reproducing it here. This is a 384K jpeg, so you can copy this and print it, and it will look very nice on the wall of your cubie. I've reduced the render size because of our page formatting constraints, but the image below is "the full banana":



As can be seen above, there is a whole bunch of new stuff going on in ASP.NET 2.0.
ASP.NET 2.0 provides a much more granular page lifecycle method stack compared to ASP.NET 1.1. The added methods provide a greater level of control to the Web developer. With that added level of control comes the responsibility to understand what these methods do and when they are called. These events can be accessed through the Page object on any ASP.NET page.

The table below shows the list, and whether the method is active at all times, or only on PostBack.

Method	Active
Constructor	Always
Construct	Always
TestDeviceFilter	Always
AddParsedSubObject	Always
DeterminePostBackMode	Always
OnPreInit	Always
LoadPersonalizationData	Always
InitializeThemes	Always
OnInit	Always
ApplyControlSkin	Always
ApplyPersonalization	Always
OnInitComplete	Always
LoadPageStateFromPersistenceMedium	PostBack
LoadControlState	PostBack
LoadViewState	PostBack
ProcessPostData1	PostBack
OnPreLoad	Always
OnLoad	Always
ProcessPostData2	PostBack
RaiseChangedEvents	PostBack
RaisePostBackEvent	PostBack
OnLoadComplete	Always
OnPreRender	Always
OnPreRenderComplete	Always
SavePersonalizationData	Always
SaveControlState	Always
SaveViewState	Always
SavePageStateToPersistenceMedium	Always
Render	Always
OnUnload	Always

If you really want to see how the "rubber meets the road" in ASP.NET 2.0 you can construct for yourself a test page that overrides each of these methods, like so:

using System;
       using System.Data;
       using System.Configuration;
       using System.Web;
       using System.Web.Security;
       using System.Web.UI;
       using System.Web.UI.WebControls;
       using System.Web.UI.WebControls.WebParts;
       using System.Web.UI.HtmlControls;
    public partial class _Default : System.Web.UI.Page 

      {     protected override void AddedControl(Control control, int index)

      {

      Response.Write("AddedControl Fired on " +control.ID+"<br>");

      base.AddedControl(control, index);

      }     protected override void AddParsedSubObject(object obj)

      {

      base.AddParsedSubObject(obj);

      Response.Write("AddParsedSubObject" + obj.ToString() +"<BR>");

      }

      public override void ApplyStyleSheetSkin(Page page)

      {

      base.ApplyStyleSheetSkin(page);

      Response.Write("ApplyStyleSheetSkin " + page.ToString() + "<BR>");

      }

      protected override void Construct()

      {

      base.Construct();

      // No Response Object here yet!

      }     protected override void CreateChildControls()

      {

      base.CreateChildControls();

      Response.Write("CreateChildControls<BR>");

      }     protected override ControlCollection CreateControlCollection()

      {

      Response.Write("CreateControlCollection<BR>");

      return base.CreateControlCollection();

      }   

// etc. etc. just type the keyword "override" and select from the list! protected void Page_Load(object sender, EventArgs e)

      {         }

 }

The study guide you will have created by making such a test page will be invaluable in learning how the ASP.NET 2.0 Page LifeCycle works, the order in which the methods are called (and when / if they are called) and whether the Response Object (for example) is available at that stage of Page class's execution.