TreeView.TreeNodeExpanded Event
.NET Framework (current version)
Occurs when a node is expanded in the TreeView control.
Assembly: System.Web (in System.Web.dll)
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.
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If the SelectAction property for a node is set to TreeNodeSelectAction.Expand or TreeNodeSelectAction.SelectExpand, the TreeNodeExpanded event is also raised when that node is clicked in the TreeView control. |
For more information about handling events, see NIB: Consuming Events.
The following code example demonstrates how to use the TreeNodeExpanded event to update the content of a Label control when the user expands 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
Available since 2.0
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