This documentation is archived and is not being maintained.

Parameter.OnParameterChanged Method

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

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

protected void OnParameterChanged()

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 Raising an Event.

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.

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;

.NET Framework

Supported in: 4, 3.5, 3.0, 2.0

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.