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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 _
)

Parameters

control
Type: System.Web.UI.Control
The control to register.
ExceptionCondition
ArgumentException

The control to register is Nothing.

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

      Protected Overrides Sub OnInit(ByVal e As EventArgs)
          Page.RegisterRequiresControlState(Me)
          currentIndex = 0
          MyBase.OnInit(e)
      End Sub

      Protected Overrides Function SaveControlState() As Object
          If currentIndex <> 0 Then
              Return CType(currentIndex, Object)
          Else
              Return Nothing
          End If
      End Function

      Protected Overrides Sub LoadControlState(ByVal state As Object)
          If (state <> Nothing) Then
              currentIndex = CType(state, Integer)
          End If
      End Sub

End Class


.NET Framework

Supported in: 4, 3.5, 3.0, 2.0

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.
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