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 TreeNodeCollapsed As 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 NIB: 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="VB" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">

  Sub Node_Expand(ByVal sender As Object, ByVal e As TreeNodeEventArgs)

    Message.Text = "You expanded the " & e.Node.Text & " node."

  End Sub

  Sub Node_Collapse(ByVal sender As Object, ByVal e As TreeNodeEventArgs)

    Message.Text = "You collapsed the " & e.Node.Text & " node."

  End Sub

</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>

.NET Framework
Available since 2.0
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