Loop through to the parent node and join with a "\\" in C# treeview

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I have a TreeView where the root node is the primary drive on my computer. I can list all the names of the folders inside that drive with the code below whenever the root node is clicked. The root node is the only node that cannot have a parent. So when a node is clicked, I need to check first if it has a parent, if it has a parent, I use a loop to get the text of all the parents up to the root node while I add the text of the clicked child node and the parents to a list. I then use a join method to form a path that can be used to get all the directories in that child node folder. Which conditional structure is the right one to use? a while loop or a do while, my code is shown below.

What I have tried:

<pre lang="C#">

   private void TreeView1_NodeMouseClick(object sender, TreeNodeMouseClickEventArgs e)
        {
            //get the name of the parent drive
            var parent = e.Node.Text;
            if (e.Node.Parent != null)
            {
                MessageBox.Show(e.Node.Parent.Text);
                var path = new List <string>(); 
                var node = e.Node;
                path.Add(node.Text);    
                while (node.Parent != null)
                {
                    MessageBox.Show(node.Text);
                    //add the text to the list
                    path.Add(node.Text);
                    node = node.Parent;
                }
                var final = string.Join("\\", path);
                MessageBox.Show(final);
            }
            if (e.Node.IsExpanded)
            {
                //collpase the node
                //e.Node.Collapse();

            }
            else
            {
                //get all directories in the drive
                if(e.Node.Parent != null)
                {
                    var node = e.Node.Parent;
                    while (node.Parent != null)
                    {
                        MessageBox.Show(node.Text);
                        node = node.Parent;
                    }
                 
                }
                else
                {
                    e.Node.Nodes.Clear();
                    List<DirectoryInfo> list = new List<DirectoryInfo>();
                    var files = Directory.GetDirectories(parent);
                    files.ToList().ForEach(item => list.Add(new DirectoryInfo(item)));
                    list.ForEach(item => e.Node.Nodes.Add(item.Name));
                }
             
            }
        }

Posted 30-May-23 7:08am

Tim the Gamer

Updated 30-May-23 22:02pm

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2 solutions

Solution 1

In case you are asking about this loop:

if(e.Node.Parent != null)
{
    var node = e.Node.Parent;
    while (node.Parent != null)
    {
        MessageBox.Show(node.Text);
        node = node.Parent;
    }

I think you can simplify it like this:

var node = e.Node;
while (node.Parent != null)
{
    node = node.Parent;
    MessageBox.Show(node.Text);
}

Posted 30-May-23 10:26am

dietmar paul schoder

Comments

Tim the Gamer 31-May-23 4:07am

You have moved the reset code to the top of the Message Box statement, let me check if it outputs the nodes parents text as expected.

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Richard Deeming · Accepted Answer · 2023-05-30T22:02:00

The choice between while and do..while is fairly simple: if you want to test the condition before executing the code, then use while; if you want to execute the code in the loop at least once before testing the condition, then use do..while.

The bigger problem is your choice of collection. By appending each parent node's text to a List<string>, you'll end up with the path in the wrong order. For example, if you have a tree structure of C: ⇒ Users ⇒ Tim ⇒ Documents, your final path will be: "Documents\Tim\Users\C:".

You could replace the Add call with an Insert call:

C#

path.Add(node.Text);    
while (node.Parent != null)
{
    path.Insert(0, node.Text);
    node = node.Parent;
}

Or you could switch to using a Stack<string>, which iterates its values in the reverse order, producing the correct results:

C#

var path = new Stack<string>(); 
var node = e.Node;
while (node != null)
{
    path.Push(node.Text);
    node = node.Parent;
}
string final = string.Join(Path.DirectorySeparatorChar, path);

Stack<T> Class (System.Collections.Generic) | Microsoft Learn[^]