Page.RegisterRequiresControlState Method

Registers a control as one whose control state must be persisted.

Namespace: System.Web.UI
Assembly: System.Web (in system.web.dll)

'Declaration
Public Sub RegisterRequiresControlState ( _
	control As Control _
)
'Usage
Dim instance As Page
Dim control As Control

instance.RegisterRequiresControlState(control)
public void RegisterRequiresControlState (
	Control control
)
public function RegisterRequiresControlState (
	control : Control
)
Not applicable.

Parameters

control

The control to register.

Exception typeCondition

ArgumentException

The control to register is a null reference (Nothing in Visual Basic).

InvalidOperationException

The RegisterRequiresControlState method can be called only before or during the PreRender event.

Custom server controls that use control state must call the RegisterRequiresControlState method on each request because registration for control state is not carried over from request to request during a postback event. It is recommended that registration occur in the Init event.

The following code example shows a custom server control calling the RegisterRequiresControlState method.

Class Sample
  Inherits Control
  
  Dim currentIndex As Integer
  
  Overloads Sub OnInit(ByVal e As EventArgs)
    Page.RegisterRequiresControlState(Me)
    currentIndex = 0
    
    MyBase.OnInit(e)
  End Sub
  
  Overloads Function SaveControlState() As Object
    If currentIndex <> 0 Then
      Return CType(currentIndex, Object)
    Else
      Return Nothing
    End If
  End Function
  
  Overloads Sub LoadControlState(ByVal state As Object)
    If (state <> Nothing) Then
      currentIndex = CType(state, Integer)
    End If
  End Sub
  
End Class

Windows 98, Windows Server 2000 SP4, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0

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