Getting the control that posted back to asp.net application

Need to know which specific control posted back to your page? (Original article at http://geekswithblogs.net/mahesh/archive/2006/06/27/83264.aspx)

/// <summary>
 /// Tells us which control posted back
 /// </summary>
 /// <returns></returns>
 public Control getPostBackControlName()
 {
 Control control = null;
 //first we will check the "__EVENTTARGET" because if post back made by       the controls
 //which used "_doPostBack" function also available in Request.Form collection.
 string ctrlname = Page.Request.Params["__EVENTTARGET"];
 if (ctrlname != null && ctrlname != String.Empty)
 control = Page.FindControl(ctrlname);

 // if __EVENTTARGET is null, the control is a button type and we need to
 // iterate over the form collection to find it
 else
 {
 string ctrlStr = String.Empty;
 Control c = null;
 foreach (string ctl in Page.Request.Form)
 {
 //handle ImageButton they having an additional "quasi-property" in their Id which identifies
 //mouse x and y coordinates
 if (ctl.EndsWith(".x") || ctl.EndsWith(".y"))
 {
 ctrlStr = ctl.Substring(0, ctl.Length - 2);
 c = Page.FindControl(ctrlStr);
 }
 else
 c = Page.FindControl(ctl);

 if (c is System.Web.UI.WebControls.Button || c is System.Web.UI.WebControls.ImageButton)
 {
 control = c;
 break;
 }
 }
 }
 return control;
 }

If you are using master pages, simply add this to the master.cs file and where you need to call the method use the following code:

MasterPage masterPage = (MasterPage)Page.Master; // where MasterPage is the class name
 Control rep = masterPage.getPostBackControlName();
 if (rep.Parent.Parent.ID == "rpRegion")// only if postback is the regions control
 GetSelectedRegion();