Page.RegisterRequiresControlState Method
.NET Framework 3.0
Registers a control as one whose control state must be persisted.
Namespace: System.Web.UI
Assembly: System.Web (in system.web.dll)
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 type | Condition |
|---|---|
|
The control to register is a null reference (Nothing in Visual Basic). | |
|
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
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