Page Refresh Causes Duplicate POST in ASP.NET Applications

Question

i have an application in which i am adding a new record and the record is added two times if i am pressing refresh button.

I am clearing the cache but i am having the same problem. what to do?

Answer 1

Once you have handled a post back to a page, best practice is to then redirect so that you can't have the data posted a second time using the "refresh" button. This is common to all web develoment, not just ASP.NET.

Answer 2

My method is shamelessly stolen from page 4 of this awesome article on ASP Alliance. To detect a refresh, you can store the same value in ViewState and Session. If the user refreshes a page, it will PostBack using the old ViewState data that does not match your Session value. Once you detect this, you can create a Page that all of your other Pages inherit from with a simple variable to test for whether the user refreshed the browser. This solution requires ViewState to be enabled and a valid Session.

protected override void OnLoad(EventArgs e)
{
    base.OnLoad(e);

    if (IsPostBack && ViewState[REFRESH_CHECK_GUID] != Session[REFRESH_CHECK_GUID])
    {
        IsRefresh = true;
    }
    Session[REFRESH_CHECK_GUID] = System.Guid.NewGuid().ToString();
    ViewState[REFRESH_CHECK_GUID] = Session[REFRESH_CHECK_GUID];
}

/// <summary>
/// True if the last PostBack was caused by a Page refresh.
/// </summary>
public virtual bool IsRefresh
{
    get;
    private set;
}