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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)

public void RegisterRequiresControlState (
	Control 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.

public class Sample : Control {
    private int currentIndex = 0;
   
    protected override void OnInit(EventArgs e) {
        Page.RegisterRequiresControlState(this);
        base.OnInit(e);
    }

    protected override object SaveControlState() {
        return currentIndex != 0 ? (object)currentIndex : null;
    }

    protected override void LoadControlState(object state) {
        if (state != null) {
            currentIndex = (int)state;
        }
    }
}

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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