Saturday, October 1, 2011

TreeView in ASP.NET


Introduction:

The TreeView control is one of the most important controls of ASP.NET controls. It is used to display records in a hierarchical format.
TreeView.png 
Figure 1: TreeView control structure
How to use TreeView control: Follow these steps:
Step 1: Open Visual Studio 2008 and drag a TreeView control from the toolbar and drop on page as follows:
image1.png
 
Figure 2:
Step 2: Copy this code and paste on your page.
<asp:TreeView ID="CourseTreeView" runat="server" OnSelectedNodeChanged="CourseTreeView_SelectedNodeChanged" ShowLines="true" DataSourceID="XmlDataSource1" ExpandDepth="1" PopulateNodesFromClient="false">
    <Nodes>
        <asp:TreeNode Text="Puru" PopulateOnDemand="false" Value="-1" />
    </Nodes>
</asp:TreeView>
<asp:XmlDataSource ID="XmlDataSource1" runat="server" DataFile="~/treenode.xml">
</asp:XmlDataSource>
Here I am binding the node from a xml file. This is optional. You can bind a TreeView node from a database or fix the node directly within the <node> tab.
How to open a popup upon a click of any node in a TreeView?
I am using a small JavaScript function for popup on click.
<script type="text/javascript" language="javascript">        Sys.WebForms.PageRequestManager.getInstance().add_endRequest(EndRequestHandler);
        function EndRequestHandler(sender, args) {
            alert($get("<%=TextBox1.ClientID %>").value);
        }</script>
The following example demonstrates how to use a TreeView control and how to popup on click of any node.
Example:
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head id="Head1" runat="server">    <title>Untitled Page</title></head>
<body>
    <form id="form1" runat="server">
    <asp:ScriptManager ID="ScriptManager1" runat="server">
    </asp:ScriptManager>
    <asp:UpdatePanel ID="UpdatePanel1" runat="server">
        <ContentTemplate>
            <asp:TreeView ID="CourseTreeView" runat="server" OnSelectedNodeChanged="CourseTreeView_SelectedNodeChanged"
                ShowLines="true" DataSourceID="XmlDataSource1" ExpandDepth="1" PopulateNodesFromClient="false">
                <Nodes>
                    <asp:TreeNode Text="Puru" PopulateOnDemand="false" Value="-1" />
                </Nodes>
            </asp:TreeView>
            <asp:XmlDataSource ID="XmlDataSource1" runat="server" DataFile="~/treenode.xml">
            </asp:XmlDataSource>
            <span style="display: none;">
                <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
            </span>
        </ContentTemplate>
    </asp:UpdatePanel>

    <script type="text/javascript" language="javascript">
        Sys.WebForms.PageRequestManager.getInstance().add_endRequest(EndRequestHandler);
        function EndRequestHandler(sender, args) {
            alert($get("<%=TextBox1.ClientID %>").value);
        }
    </script>

    </form>
</body>
</html>
 
protected void CourseTreeView_SelectedNodeChanged(object sender, EventArgs e)
{
    TextBox1.Text = CourseTreeView.SelectedNode.Text;
}
Output:
output.png
 
Figure 3: Output of TreeView control.
If you click on any tree node, a popup will be shown as follows:
popup.png
 
Figure 4: PopUp shown upon click of a tree node.