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TreeView.SelectedNodeChanged Event

Occurs when a node is selected in the TreeView control.

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

public event EventHandler SelectedNodeChanged
<asp:TreeView OnSelectedNodeChanged="EventHandler" />

The SelectedNodeChanged event is raised when a node is selected in the TreeView control. This allows you to provide an event-handling method that performs a custom routine, such as updating the displayed content, whenever this event occurs.

You can optionally set the SelectAction property for a node to specify which event is raised when that node is selected. The following table lists the available options.

Selection action

Description

Expand

Toggles the node between expanded and collapsed. Raises the TreeNodeExpanded or TreeNodeCollapsed event, as appropriate.

None

Raises no events when a node is selected.

Select

Raises the SelectedNodeChanged event when a node is selected.

SelectExpand

Raises both the SelectedNodeChanged and TreeNodeExpanded events when a node is selected. Nodes are only expanded, never collapsed.

NoteNote:

The HoverNodeStyle is not rendered for a node with its SelectAction property set to TreeNodeSelectAction.None.

The SelectedNodeChanged event is fired only on post back when a user clicks a node. The event is not fired if the SelectedNode property is changed programmatically.

For more information about handling events, see Consuming Events.

The following code example demonstrates how to use the SelectedNodeChanged event to update a Label control when a node is selected 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 Select_Change(Object sender, EventArgs e)
    {

        Message.Text = "You selected: " + LinksTreeView.SelectedNode.Text;

    }

</script>

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

    <head runat="server">
    <title>TreeView SelectedNodeStyle Example</title>
</head>
<body>
        <form id="form1" runat="server">

            <h3>TreeView SelectedNodeStyle Example</h3>

            <asp:TreeView id="LinksTreeView"
                Font-Names= "Arial"
                ForeColor="Blue"
                SelectedNodeStyle-ForeColor="Green"
                SelectedNodeStyle-VerticalPadding="0"
                OnSelectedNodeChanged="Select_Change"   
                runat="server">

                <LevelStyles>

                    <asp:TreeNodeStyle ChildNodesPadding="10" 
                        Font-Bold="true" 
                        Font-Size="12pt" 
                        ForeColor="DarkGreen"/>
                    <asp:TreeNodeStyle ChildNodesPadding="5" 
                        Font-Bold="true" 
                        Font-Size="10pt"/>
                    <asp:TreeNodeStyle ChildNodesPadding="5" 
                        Font-UnderLine="true" 
                        Font-Size="10pt"/>
                    <asp:TreeNodeStyle ChildNodesPadding="10" 
                        Font-Size="8pt"/>

                </LevelStyles>

                <Nodes>

                    <asp:TreeNode Text="Table of Contents"
                        SelectAction="None">

                        <asp:TreeNode Text="Chapter One">

                            <asp:TreeNode Text="Section 1.0">

                                <asp:TreeNode Text="Topic 1.0.1"/>
                                <asp:TreeNode Text="Topic 1.0.2"/>
                                <asp:TreeNode Text="Topic 1.0.3"/>

                            </asp:TreeNode>

                            <asp:TreeNode Text="Section 1.1">

                                <asp:TreeNode Text="Topic 1.1.1"/>
                                <asp:TreeNode Text="Topic 1.1.2"/>
                                <asp:TreeNode Text="Topic 1.1.3"/>
                                <asp:TreeNode Text="Topic 1.1.4"/>

                            </asp:TreeNode>

                        </asp:TreeNode>

                        <asp:TreeNode Text="Chapter Two">

                            <asp:TreeNode Text="Section 2.0">

                                <asp:TreeNode Text="Topic 2.0.1"/>
                                <asp:TreeNode Text="Topic 2.0.2"/>

                            </asp:TreeNode>

                        </asp:TreeNode>

                    </asp:TreeNode>
                    <asp:TreeNode Text="Appendix A" />
                    <asp:TreeNode Text="Appendix B" />
                    <asp:TreeNode Text="Appendix C" />

                </Nodes>

            </asp:TreeView>

            <br /><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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