TreeView.SelectedNodeChanged Event

 
System_CAPS_noteNote

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Occurs when a node is selected in the TreeView control.

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

Public Event SelectedNodeChanged As 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.

System_CAPS_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 NIB: 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="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 Select_Change(ByVal sender As Object, ByVal e As EventArgs)

        Message.Text = "You selected: " & LinksTreeView.SelectedNode.Text

    End Sub

</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>

.NET Framework
Available since 2.0
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