Geek Answers Handbook

Dynamically create tree

I am trying to create a dynamic tree using C # and asp.net.

I created a lazy load tree using the popdem ondemand attribute.

>  <asp:TreeView ID="treeView1"  runat="server" 
>              OnTreeNodePopulate="treeview1_TreeNodePopulate"></asp:TreeView>

For the code, I uploaded my data, but initially I populate the parent nodes. What I want to achieve is when I click on the parent node, then I do the postback, and then populate its child, and then populate its child again, and so on. I have thousands of data, so I don’t want all the data to be populated due to performance. Therefore, I only want to populate the children of the node based on the selected node. See the example below:

>Peter
    - - >user1
    - - >user2
    - - >user3
       - - >userPassword
       - - >userId
>john
>david
>Jack
    - - >user1
    - - >user2
       - - >userpassword
       - - >userId
       - - >Permissions
>Laura 
    - - > admin
    - - > permissions
       -- > user1
       -- > user2
         - - >userpassword
             - - >userId
             - - >Permissions           
>...
>...
>...

, . , . , node, node , , , .. , .

#:

private void LoadTreeview()
{
 //Load data
 // Get data from DB.
 //loop through the list and build its parent nodes.
  foreach (var dxm in list)
  {
                TreeNode tnParent = CheckNodeExist(dxm.Node); //I check to see if exists.
                if (tnParent== null)
                {
                    TreeNode tn = new TreeNode();
                    tn.Text = dxm.Node;
                    tn.Value = dxm.Id.ToString();
                    tn.SelectAction = TreeNodeSelectAction.None;
                    tn.Collapse();
                    treeView1.Nodes.Add(tn);
                    tn.PopulateOnDemand = true; //lazy load
                    tnParent= tn;
                }

}

.

TreeNodePopulateEvent: ( node)

protected void treeview1_TreeNodePopulate(object sender, TreeNodeEventArgs e)
        {
            ICollection<ITEMS> list = new Collection<ITEMS>();           

            list = GetData(e.Node.Text); //pass in the node you have selected  this will go and check in DB if the node does have any child nodes. If so will return with child nodes.

            foreach (var dxm in list)
            {

                TreeNode tnChild = CheckNodeExist(dxm.Node);
                if (tnChild == null)
                {
                    TreeNode tn = new TreeNode();
                    tn.Text = dxm.Node;
                    tn.Value = dxm.Id.ToString();
                    tn.SelectAction = TreeNodeSelectAction.None;
                    tn.Collapse();

                    tn.PopulateOnDemand = true;
                    tnChild = tn;
                    tnChild.ChildNodes.Add(tnChild);                  

                }
            }
        }
+5
1

, SelectedNodeChanged. . , node, .

aspx

<%@ 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 runat="server">
    <title></title>
</head>
<body>
    <form id="form1" runat="server">
    <div id="div1" runat="server">

    </div>

    <asp:TreeView ID="TreeView1" runat="server" 
        onselectednodechanged="TreeView1_SelectedNodeChanged">

    </asp:TreeView>

    </form>
</body>
</html>


using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

public partial class _Default : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!Page.IsPostBack)
        {
            TreeView1.Nodes.Add(new TreeNode("Node1"));
            TreeView1.Nodes[0].ChildNodes.Add(new TreeNode("ChildNode"));
        }

    }


    protected void TreeView1_SelectedNodeChanged(object sender, EventArgs e)
    {
        Response.Write(TreeView1.SelectedNode.Text);
    }
}
+4

More articles:


All Articles