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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
<asp:TreeView OnTreeNodeCollapsed="TreeNodeEventHandler" />

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" 
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<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.";

  }

</script>

<html xmlns="http://www.w3.org/1999/xhtml" >

  <head runat="server">
    <title>TreeView TreeNodeExpand and TreeNodeCollapse Example</title>
</head>
<body>
    <form id="form1" runat="server">

      <h3>TreeView TreeNodeExpand and TreeNodeCollapse Example</h3>

      <asp:TreeView id="BookTreeView"
        ExpandDepth="1"
        OnTreeNodeExpanded="Node_Expand"
        OnTreeNodeCollapsed="Node_Collapse"
        runat="server">

        <Nodes>

          <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>

            </asp:TreeNode>

            <asp:TreeNode Value="Section 2" 
              Text="Section 2">
            </asp:TreeNode>

          </asp:TreeNode>

        </Nodes>

      </asp:TreeView>

      <br />

      <asp:Label id="Message" runat="server"/>

    </form>
  </body>
</html>

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98

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

.NET Framework

Supported in: 3.5, 3.0, 2.0
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