How to get Text from all Parent Nodes of a Node in TreeView?

Question

Maybe I couldn't explain well, but this should explain: I have a int field called getParentNode(TreeNode) to get how many parent it has (eg if there is 2 nodes below node, count will be 2) And I have a List field called getParentNames(TreeNode) that returns all of the parent's names.

getParentCount:

int getParentCount(TreeNode node)
{
    int count = 1;
    while (node.Parent != null)
    {
        count++;
        node = node.Parent;
    }
    return count;
}

getParentsNames:

List<string> getParentNames(TreeNode node)
{
    List<string> list = new List<string>();
    for (int i = 0; i < getParentCount(node); i++)
    {
        //i = 1 : list.Add(node.Parent.Text);
        //i = 2 : list.Add(node.Parent.Parent.Text);
        //i = 3 ...
    }
    return list;
}

Do I need to check if (i == 0) (I don't want to write manually because number can be anything) or something? Regards.

Answer 1

why don't you use the node.FullPath counting the TreeView.PathSeparator char? Something like

char ps = Convert.ToChar( TreeView1.PathSeparator);
int nCount = selectedNode.FullPath.Split(ps).Length;

Answer 2

You can use either of these options:

• Split FullPath of node by PathSeparator of tree
• Ancestors and AncestorsAndSelf sxtension methods

Split FullPath of node by PathSeparator of tree

You can use FullPath property of the TreeNode and split the result using PathSeparator property of TreeView . For example:

private void treeView1_AfterSelect(object sender, TreeViewEventArgs e)
{
    var ancestorsAndSelf = e.Node.FullPath.Split(treeView1.PathSeparator.ToCharArray());
}

Ancestors and AncestorsAndSelf sxtension methods

Also you can get all ancestors of a TreeNode . You can simply use a while loop to go up using node.Parent while the parent is not null. I prefer to encapsulate this logic in an extension method and make it more reusable for future. You can create an extension method to return all parent nodes (ancestors) of a node:

using System.Collections.Generic;
using System.Linq;
using System.Windows.Forms;
public static class TreeViewExtensions
{
    public static List<TreeNode> Ancestors(this TreeNode node)
    {
        return AncestorsInternal(node).Reverse().ToList();
    }
    public static List<TreeNode> AncestorsAndSelf(this TreeNode node)
    {
        return AncestorsInternal(node, true).Reverse().ToList();
    }
    private static IEnumerable<TreeNode> AncestorsInternal(TreeNode node, bool self=false)
    {
        if (self)
            yield return node;
        while (node.Parent != null)
        {
            node = node.Parent;
            yield return node;
        }
    }
}

Usage:

List<TreeNode> ancestors = treeView1.SelectedNode.Ancestors();

You can get text or any other property from ancestors:

List<string> ancestors = treeView1.SelectedNode.Ancestors().Select(x=>x.Text).ToList(); 

Note

JFYI you can use an extension method approach to get all child nodes too. Here I've shared an extension method to to so: Descendants Extension Method .

Answer 3

Anyways, I noticed that I need to use while loop:

List<string> getParentNames(TreeNode node)
    {
        List<string> list = new List<string>();
        int count = getParentCount(node);
        int index = 0;
        TreeNode parent = node;
        while (index < count)
        {
            if (parent != null)
            {
                index++;
                list.Add(parent.Text);
                parent = parent.Parent;
            }
        }
        return list;
    }