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Parameter.OnParameterChanged Method

  • Reference

Definition

Namespace:
System.Web.UI.WebControls
Assembly:
System.Web.dll

Calls the OnParametersChanged(EventArgs) method of the ParameterCollection collection that contains the Parameter object.

protected:
 void OnParameterChanged();
protected void OnParameterChanged ();
member this.OnParameterChanged : unit -> unit
Protected Sub OnParameterChanged ()

Examples

The following code example demonstrates how to call the OnParameterChanged method to raise the ParametersChanged event when the state of a parameter changes. This code example is part of a larger example provided for the Parameter class overview.

// The Value property is a type safe convenience property
// used when the StaticParameter represents string data.
// It gets the string value of the DataValue property, and
// sets the DataValue property directly.
public string Value {
  get {
    object o = DataValue;
    if (o == null || !(o is string))
      return String.Empty;
    return (string)o;
  }
  set {
    DataValue = value;
    OnParameterChanged();
  }
}

' The Value property is a type safe convenience property
' used when the StaticParameter represents string data.
' It gets the string value of the DataValue property, and
' sets the DataValue property directly.
Public Property Value() As String
   Get
      Dim o As Object = DataValue
      If o Is Nothing OrElse Not TypeOf o Is String Then
         Return String.Empty
      End If
      Return CStr(o)
   End Get
   Set
      DataValue = value
      OnParameterChanged()
   End Set
End Property

Remarks

If the Parameter object is not contained by a ParameterCollection collection, calling the OnParameterChanged method has no effect. If the Parameter object is contained by a ParameterCollection collection, OnParameterChanged raises the ParameterCollection.ParametersChanged event of the collection.

If the ParameterCollection collection is contained by a data source control, the ParameterCollection.ParametersChanged event raises the data source control's DataSourceChanged event, causing any data-bound controls to rebind.

Raising an event invokes the event handler through a delegate. For more information, see Handling and Raising Events.

The OnParameterChanged method also allows derived classes to handle the event without attaching a delegate. This is the preferred technique for handling the event in a derived class.

Notes to Inheritors

When overriding OnParameterChanged() in a derived class, be sure to call the base class's OnParameterChanged() method so that registered delegates receive the event.

Applies to

See also