ASP.NET Page Life Cycle


by Peter A. Bromberg, Ph.D.

Peter Bromberg

ASP.NET 2.0 Page Life Cycle is a much more granular 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.



 

ASP.NET Page Life Cycle Methods

 

Method Active 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 in the ASP.NET Page Life Cycle, 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)
{

}
}

 

Study Guide & Diagram

 

The study guide you will have created by making such a test page will be invaluable in learning how the ASP.NET Page Life Cycle 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.


I was searching the web for some information on the ASP.NET Page Life Cycle 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":

Life Cycle Chart


Peter Bromberg is a C# MVP, MCP, and .NET consultant who has worked in the banking and financial industry for 20 years. He has architected and developed web - based corporate distributed application solutions since 1995, and focuses exclusively on the .NET Platform.