ControlParameter.Evaluate Method

Updates and returns the value of the ControlParameter object.

Namespace: System.Web.UI.WebControls
Assembly: System.Web (in system.web.dll)

protected:
virtual Object^ Evaluate (
	HttpContext^ context, 
	Control^ control
) override
protected Object Evaluate (
	HttpContext context, 
	Control control
)
protected override function Evaluate (
	context : HttpContext, 
	control : Control
) : Object
Not applicable.

Parameters

context

The current HttpContext of the request.

control

The Control that the parameter is bound to.

Return Value

An Object that represents the updated and current value of the parameter.

Exception typeCondition

ArgumentException

The ControlID property is not set.

- or -

The PropertyName property is not set and the Control identified by the ControlID property is not decorated with a ControlValuePropertyAttribute attribute.

InvalidOperationException

Control.FindControl does not return the specified control.

- or -

The control identified by the ControlID property does not support the property named by PropertyName.

The ControlParameter object attempts to bind to the Control object and property every time the Evaluate method is called. The Evaluate method returns the value of the control's property that is identified by the combination of the ControlID and PropertyName properties.

The ControlParameter class never uses the DefaultValue property, which is inherited from Parameter, when binding to a control's property value.

NoteNote:

In this implementation of the method, the context parameter is ignored. If the control parameter is a null reference (Nothing in Visual Basic), a null reference (Nothing in Visual Basic) is returned.

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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