Parameter.OnParameterChanged Method
Definition
Important
Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.
Calls the OnParametersChanged(EventArgs) method of the ParameterCollection collection that contains the Parameter object.
protected:
void OnParameterChanged();protected void OnParameterChanged ();member this.OnParameterChanged : unit -> unitProtected 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.
