TreeView.TreeNodeCollapsed Event

Occurs when a node is collapsed in the TreeView control.

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

public event TreeNodeEventHandler TreeNodeCollapsed
/** @event */
public void add_TreeNodeCollapsed (TreeNodeEventHandler value)

/** @event */
public void remove_TreeNodeCollapsed (TreeNodeEventHandler value)

In JScript, you can handle the events defined by a class, but you cannot define your own.
Not applicable.

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

For more information about handling events, see Consuming Events.

The following code example demonstrates how to use the TreeNodeCollapsed event to update the content of a Label control when the user collapses a node in the TreeView control.

<%@ Page Language="C#" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
<script runat="server">

  void Node_Expand(Object sender, TreeNodeEventArgs e)

    Message.Text = "You expanded the " + e.Node.Text + " node.";


  void Node_Collapse(Object sender, TreeNodeEventArgs e)

    Message.Text = "You collapsed the " + e.Node.Text + " node.";



<html xmlns="" >

  <head runat="server">
    <title>TreeView TreeNodeExpand and TreeNodeCollapse Example</title>
    <form id="form1" runat="server">
      <h3>TreeView TreeNodeExpand and TreeNodeCollapse Example</h3>
      <asp:TreeView id="BookTreeView"
          <asp:TreeNode Value="Chapter 1" 
            Text="Chapter 1">
            <asp:TreeNode Value="Section 1"
              Text="Section 1">
              <asp:TreeNode Value="Paragraph 1" 
                Text="Paragraph 1">
            <asp:TreeNode Value="Section 2" 
              Text="Section 2">
      <br />
      <asp:Label id="Message" runat="server"/>


Windows 98, Windows Server 2000 SP4, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0

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