ASP TreeView: All nodes have the same ID

Question

I'm currently writing a custom web forms control with, among others, an embedded TreeView control. The content of this TreeView control is generated programmatically like this:

    public void PopulateTreeView(TreeView treeView)
    {
        // Initialize with a single root node.
        treeView.Nodes.Clear();
        TreeNode currentNode = new TreeNode("root");
        treeView.Nodes.Add(currentNode);

        // Some logic with basically a depth first search through some data classes.
        {
            TreeNode node = new TreeNode(/* node label */);
            currentNode.ChildNodes.Add(node);

            if ( /* some condition */)
            {
                currentNode = node;
            }
        }

    }

When rendering, everything looks fine, except that the ID for all HTML elements generated is ControlName1n0, which has the effect that clicking on the expand/collapse icons will only expand/collapse the root node.

Does anyone know what's the cause of this or how to fix this?

Without seeing the actual code (it would be useful for you to post it in its entirety, or at least the relevant bits), my hunch is that you're not assigning the ID dynamically at time of node creation. Please show where you're adding the ID's. — mjw
That is the relevant bit of the actual code, i'm indeed doing nothing more with TreeNodes than creating them and assigning them to their respective parents. I also could not find here any way to assign an ID to TreeNodes - the only thing mentioned there is to assign different Value attributes but this did not help. — C. Sura

C. Sura C. Sura · Accepted Answer · 2015-05-19T08:03:55

Moving the code to create the TreeNodes from the Render method to the OnPreRender method solved the problem; now all nodes get a unique ID.

ASP TreeView: All nodes have the same ID

1 Answers