How to Identify Postback event in Page_Load

Question

We have some legacy code that needs to identify in the Page_Load which event caused the postback. At the moment this is implemented by checking the Request data like this...

if (Request.Form["__EVENTTARGET"] != null
&& (Request.Form["__EVENTTARGET"].IndexOf("BaseGrid") > -1 // BaseGrid event ( e.g. sort)
       || Request.Form["btnSave"] != null // Save button

This is pretty ugly and breaks if someone renames a control. Is there a better way of doing this?

Rewriting each page so that it does not need to check this in Page_Load is not an option at the moment.

Answer 1

This should get you the control that caused the postback:

public static Control GetPostBackControl(Page page)
{
    Control control = null;

    string ctrlname = page.Request.Params.Get("__EVENTTARGET");
    if (ctrlname != null && ctrlname != string.Empty)
    {
        control = page.FindControl(ctrlname);
    }
    else
    {
        foreach (string ctl in page.Request.Form)
        {
            Control c = page.FindControl(ctl);
            if (c is System.Web.UI.WebControls.Button)
            {
                control = c;
                break;
            }
        }
    }
    return control;
}

Read more about this on this page: http://ryanfarley.com/blog/archive/2005/03/11/1886.aspx