C# Populate TreeView Recursively Stack Overflow

Question

Woohoo! I get to post a question about a stack overflow...on stackoverflow :)

So it might just be that it's Friday and my brain is already fried, but I am trying to write a class that recursively populates a given TreeView with a generic type of object that inherits from a TreeNode and a simple interface.

For some reason I am getting a stackoverflow exception when I try to populate the nodes.

My simple interface:

public interface ITreeNode
{
    int ItemID { get; set; }
    int ParentID { get; set; }
}

Recursion code:

public void SetNodes(int rootId)
{
    foreach (T root in _nodeList.Where(i => i.ParentID == rootId))
    {
        _tree.Nodes.Add(root);
        addBrowserItems(root);
    }
}

private void addBrowserItems(T parentNode)
{
    foreach (T child in _nodeList.Where(i => i.ParentID == parentNode.ItemID))
    {
        parentNode.Nodes.Add(child);
        addBrowserItems(child);
    }
}

Code looks good to me. Have you stepped in to make sure your data is ok? — Adam Rackis
– Adam Rackis, Commented Nov 11, 2011 at 16:28
When your _nodeList contains cycles your stack will overflow. — Henk Holterman
– Henk Holterman, Commented Nov 11, 2011 at 16:30
Ohhhh - @Henk nailed it. Your tree has a cycle. A circular reference. Node X has a parent, that has a parent, whose parent is X. Or some similar mind-bending edge case that's creeped into your data. — Adam Rackis
– Adam Rackis, Commented Nov 11, 2011 at 17:05

ChandlerPelhams · Accepted Answer · 2011-11-11 17:34:58Z

2

OK, so Henk got it, there was a cycle.

I had 2 seperate tables with folder items and report items that were populating the treeview - I was using an identity column as the ID in both - and the identity was duplicated for a folder that had both another folder and report items as children.

I just added a check to only call the recursion for Folder items and it works perfectly now.

I knew it was a silly Friday mistake.

Thanks for the help!

answered Nov 11, 2011 at 17:34

ChandlerPelhams

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