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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
)

Parameters

control
Type: System.Web.UI.Control

The control to register.

ExceptionCondition
ArgumentException

The control to register is null.

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 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98

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

.NET Framework

Supported in: 3.5, 3.0, 2.0
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