TreeView Constructor ()
Initializes a new instance of the TreeView class.
Assembly: System.Web (in System.Web.dll)
Use the TreeView constructor to create and initialize a new instance of the TreeView class. To add a TreeView control to a page dynamically, create a new TreeView object, set its properties, and then add it to the Control.Controls collection of a container control, such as the PlaceHolder control.
This section contains two code examples. The first code example demonstrates how to use the TreeView constructor to add a TreeView control to a page dynamically. The second code example provides sample XML data for the first code example.
The following code example demonstrates how to use the TreeView constructor to add a TreeView control to a page dynamically. For this example to work correctly, you must copy the sample XML data provided after this code example, to a file named Book.xml.
<%@ 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 Page_Load(ByVal sender As Object, ByVal e As EventArgs) ' Create a new TreeView control. Dim NewTree As New TreeView ' Set the properties of the TreeView control. NewTree.ID = "BookTreeView" NewTree.DataSourceID = "BookXmlDataSource" ' Create the tree node binding relationship. ' Create the root node binding. Dim RootBinding As New TreeNodeBinding RootBinding.DataMember = "Book" RootBinding.TextField = "Title" ' Create the parent node binding. Dim ParentBinding As New TreeNodeBinding ParentBinding.DataMember = "Chapter" ParentBinding.TextField = "Heading" ' Create the leaf node binding. Dim LeafBinding As New TreeNodeBinding LeafBinding.DataMember = "Section" LeafBinding.TextField = "Heading" ' Add bindings to the DataBindings collection. NewTree.DataBindings.Add(RootBinding) NewTree.DataBindings.Add(ParentBinding) NewTree.DataBindings.Add(LeafBinding) ' Manually register the event handler for the SelectedNodeChanged event. AddHandler NewTree.SelectedNodeChanged, AddressOf Node_Change ' Add the TreeView control to the Controls collection of the PlaceHolder control. ControlPlaceHolder.Controls.Add(NewTree) End Sub Sub Node_Change(ByVal sender As Object, ByVal e As EventArgs) ' Retrieve the TreeView control from the Controls collection of the PlaceHolder control. Dim LocalTree As TreeView = CType(ControlPlaceHolder.FindControl("BookTreeView"), TreeView) ' Display the selected node. Message.Text = "You selected: " & LocalTree.SelectedNode.Text End Sub </script> <html xmlns="http://www.w3.org/1999/xhtml" > <head runat="server"> <title>TreeView Constructor Example</title> </head> <body> <form id="form1" runat="server"> <h3>TreeView Constructor Example</h3> <asp:PlaceHolder id="ControlPlaceHolder" runat="server"> </asp:PlaceHolder> <asp:XmlDataSource id="BookXmlDataSource" DataFile="Book.xml" runat="server"> </asp:XmlDataSource> <br /><br /> <asp:Label id="Message" runat="server"/> </form> </body> </html>
The following code example provides sample XML data for the preceding example.
<Book Title="Book Title">
<Chapter Heading="Chapter 1">
<Section Heading="Section 1">
</Section>
<Section Heading="Section 2">
</Section>
</Chapter>
<Chapter Heading="Chapter 2">
<Section Heading="Section 1">
</Section>
</Chapter>
</Book>
Available since 2.0