OnTreeNodeExpanded Method

TreeView.OnTreeNodeExpanded Method

Raises the TreeNodeExpanded event of the TreeView control.

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

protected virtual void OnTreeNodeExpanded(
	TreeNodeEventArgs e


Type: System.Web.UI.WebControls.TreeNodeEventArgs
A TreeNodeEventArgs that contains event data.

The TreeNodeExpanded event is raised when a node is expanded in the TreeView control. This allows you to provide an event-handling method that performs a custom routine whenever this event occurs.


If the SelectAction property for a node is set to Expand or SelectExpand, the TreeNodeExpanded event is also raised when that node is clicked in the TreeView control.

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

The OnTreeNodeExpanded 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 the OnTreeNodeExpanded method in a derived class, be sure to call the OnTreeNodeExpanded method for the base class so that registered delegates receive the event.

.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.

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