Binaryworld - GetPostbackControl - Return a reference to the control that caused the ... [ ASP.net -> General ]

' Return a reference to the control that caused the last postback,
' even from the Page_Load event!
' It requires in input a reference to the posted-back page
' (this is necessary if you want to be able to move this function in a separate
' class
' instead of in a page's codebehind class
'
' Example:
'  Private Sub Page_Load(ByVal sender As System.Object,
' ByVal e As System.EventArgs) Handles MyBase.Load
'    Dim postbackCtl As Control = GetPostbackControl(Me)
'    If Not postbackCtl Is Nothing Then
'      lblResult.Text = postbackCtl.ID
'    End If
'  End Sub

Function GetPostbackControl(ByVal targPage As Page) As Control
  If targPage.IsPostBack Then
    ' try to find the name of the postback control in the hidden
    ' __EVENTTARGET field
    Dim ctlName As String = targPage.Request.Form("__EVENTTARGET")
    ' if the string is not null, return the control with that name
    If ctlName.Trim().Length > 0 Then
      Return targPage.FindControl(ctlName)
    End If
    ' the trick above does not work if the postback is caused by standard
    ' buttons.
    ' In that case we retrieve the control the ASP-way: by looking in the
    ' Page's Form collection
    ' to find the name of a button control, that actually is the control
    ' that submitted the page
    Dim keyName As String
    For Each keyName In targPage.Request.Form
      Dim ctl As Control = targPage.FindControl(keyName)
      ' if a control named as this key exists,
      ' check whether it is a button - if it is, return it!
      If Not ctl Is Nothing Then
        If TypeOf ctl Is Button Then
          Return ctl
        End If
      End If
    Next
  End If

  Return Nothing
End Function