ControlParameter.Evaluate(HttpContext, Control) Method

Reference

Definition

Namespace:: System.Web.UI.WebControls

Assembly:: System.Web.dll

Important

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Updates and returns the value of the ControlParameter object.

protected:
 override System::Object ^ Evaluate(System::Web::HttpContext ^ context, System::Web::UI::Control ^ control);

protected public:
 override System::Object ^ Evaluate(System::Web::HttpContext ^ context, System::Web::UI::Control ^ control);

protected override object Evaluate (System.Web.HttpContext context, System.Web.UI.Control control);

protected internal override object Evaluate (System.Web.HttpContext context, System.Web.UI.Control control);

override this.Evaluate : System.Web.HttpContext * System.Web.UI.Control -> obj

Protected Overrides Function Evaluate (context As HttpContext, control As Control) As Object

Protected Friend Overrides Function Evaluate (context As HttpContext, control As Control) As Object

Parameters

context: HttpContext

The current HttpContext of the request.

control: Control

The Control that the parameter is bound to.

Returns

Object

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

Exceptions

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

FindControl(String) does not return the specified control.

-or-

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

Remarks

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.

Note

In this implementation of the method, the context parameter is ignored. If the control parameter is null, null is returned.

Applies to

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