Page.RegisterRequiresControlState Method (Control)

 
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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.

Exception Condition
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;
        }
    }
}

.NET Framework
Available since 2.0
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