Code Customization Model: Handling Post Back Events
Be sure to check the post back property in the event handler, or your field will be initialized again when the page is being reposted and thus overwrite any user entered value.
- Razi Mohiuddin, President of Iron Speed, Inc.

September 20, 2006
Iron Speed Designer V4.0

Handling Post Back Events

In ASP.NET, each page is reloaded when a button is pressed or if you set the AutoPostBack property of a control to be True when its value has changed. Since the same overridden methods are called and the same event notifications are sent during a post back, you need to make sure that you check the post back property of a page when writing your custom code. For example, if you want to initialize a field to a value when the page is first displayed then you can handle an event and initialize this value. But if you do not check the post back property in the event handler, your field will be initialized again when the page is being reposted and thus overwrite any user entered value. This is perhaps the most common mistake made by .NET programmers.

C#:

if (!this.Page.IsPostBack)
{
    // This code executes when the page is first loaded.
}
else
{
    // This code executes during a button click or other postback.
}
// This code executes in all cases.

Visual Basic .NET:

If Not (Me.Page.IsPostBack) Then
    ' This code executes when the page is first loaded.
Else
    ' This code executes during a button click or other postback.
End If
' This code executes in all cases.

About the Author

Razi Mohiuddin
Co-Founder, President & CEO of Iron Speed, Inc.

Mr. Mohiuddin co-founded numerous Internet and software companies, including Onsale, Inc. (later Egghead.com and now Amazon.com), Ambia Corporation, an electronic document publishing software company later acquired by Infodata Systems Inc., and Software Partners, Inc., a software consulting company that developed StreetSmart, e.Schwab, FundMap, SchwabLink and Retirement Planner software for Charles Schwab & Co.

Mr. Mohiuddin earned his BS in Computer Science from the University of Illinois, Chicago.



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