How do you get the root node or the first level node of the selected node in a tree view?

Question

Are there more straight forward method than the code below to get the root nodes or the first level nodes in a tree view?

TreeNode node = treeView.SelectedNode;

while(node != null)
{
       node = node.Parent;
}

In my programs, I do it just as you described (or at least similar; your code would always lead to a `null` reference in the `node` variable). Do you experience performance issues with this? — Uwe Keim, Dec 23 '10 at 16:20
@Vlad Lazarenko This would only work if you have just one single root node. — Uwe Keim, Dec 23 '10 at 16:31

score 35 · Accepted Answer · answered Dec 23 '10 at 16:27

Actually the correct code is:

TreeNode node = treeView.SelectedNode;
while (node.Parent != null)
{
    node = node.Parent;
}

otherwise you will always get node = null at the end of the loop.

BTW, if you are sure to have one and one only root in your TreeView, you could consider to use directly treeView.Nodes[0], because in that case it would give the root.

score 0 · Answer 2 · edited Nov 27 '18 at 05:43

0

protected void Submit(object sender, EventArgs e)
        {
           ///naidi root 

            string name = Request.Form["Name"];
            if (String.IsNullOrEmpty(name))
                return;

            if (TreeView1.Nodes.Count <= 1)
            {
                System.Web.UI.WebControls.TreeNode newNode = new TreeNode("Porposal");
                TreeView1.Nodes.Add(newNode);
            }




            System.Web.UI.WebControls.TreeNode newNode1 = new TreeNode(name);
            TreeView1.Nodes[1].ChildNodes.Add(newNode1);


        }

edited Nov 27 '18 at 05:43

Irshad

3,071
5
30
51

answered Feb 10 '18 at 19:07

Olga Ivolgin

11

It's not really clear how this answers the question and the code in the comment doesn't help. You need to edit your question. – Kalle Richter Feb 10 '18 at 19:36

score -1 · Answer 3 · answered Jan 19 '17 at 03:49

-1

Try This. It's Worked for me...!

treeView1.TopNode.Expand();

answered Jan 19 '17 at 03:49

Chathura Liyanage

212
2
11

2

Did you read the question? See the downvoted answer in regards to the TopNode issue. – LarsTech Jan 19 '17 at 03:52
1

That command alters the display of the treeview. Showing expanding the node. The question (IMHO) was aking how to get the root node, of the selected node, as an object in code. – TinyRacoon Jul 15 '19 at 16:03

score -8 · Answer 4 · answered Mar 21 '13 at 13:18

-8

TreeNode rootNode = treeView1.TopNode;

this should be all you need. SelectedNode doesn't need to be always != null

answered Mar 21 '13 at 13:18

Jebu

345
3
5

5

This is horrifically wrong. This gets the "first fully-visible tree node in the tree view control.". Note that "Initially, the TopNode returns the first root tree node, which is located at the top of the TreeView. However, if the user has scrolled the contents, another tree node might be at the top.". – woddle Nov 18 '13 at 12:16

How do you get the root node or the first level node of the selected node in a tree view?

4 Answers4