winforms - Adding Child Nodes to a Treeview from DataTable (C# Windows Forms)

Question

I'm having a hard time trying to get a Treeview to display child notes.

I have a DataTable which is filled with Data from a query.

The table is something like this.

| ParentOT | ChildOT
  -------------------
  1        | 2
  1        | 3
  1        | 4
  4        | 5
  5        | 6

now, what I need is to order this data in a TreeView.

The result must be something like this (using this same table)

1
|
--2
|
--3
|
--4
  |
  --5
    |
    --6

I tried to this on Windows Forms and the only thing I can get is the tree to show only 1 set of childs. like this

1
|
--2
|
--3
|
--4
|
--5
|
5
|
--6

I tried to do it like this:

DataTable arbolSub = mssql_cnn.ejecutarSqlSelect(q2);

            //Metodo 2: muestra las ot correctamente pero no muestra mas detalle de subOT.
            if (trvOTHs.Nodes.Count > 0)
            {
                trvOTHs.Nodes.Clear();
            }

            trvOTHs.BeginUpdate();

            if (arb.Rows.Count > 0)
            {
                string otPadre = arb.Rows[0][0].ToString();
                int nivel = 0;

                trvOTHs.Nodes.Add(arbolSub.Rows[0]["OT Padre"].ToString());

                for (int i = 0; i < arbolSub.Rows.Count; i++)
                {
                    //trvOTHs.Nodes.Add(arbolSub.Rows[0]["OT Padre"].ToString());                  
                    if (arbolSub.Rows[i]["OT Padre"].ToString() == otPadre)
                    {
                        if (trvOTHs.Nodes[nivel].Text == otPadre)
                        {
                            trvOTHs.Nodes[nivel].Nodes.Add(arbolSub.Rows[i]["OT Hija"].ToString());
                        }
                    }
                    else
                    {
                        otPadre = arbolSub.Rows[i+1]["OT Padre"].ToString();
                        TreeNode nodo = new TreeNode(otPadre.ToString());
                        trvOTHs.Nodes.Add(nodo);
                        nivel++;
                    }

                }


                trvOTHs.Nodes[0].Remove();

                trvOTHs.ExpandAll();
            }

            trvOTHs.EndUpdate();

where trvOTHs is a TreeView.

Please Help! Thanks

EDIT: Thanks for the reply. I finally worked around this,using a idea given by a friend and using something like the suggested solution by @Mohammad abumazen.

I ended up using two methods recursively:

 private TreeView cargarOtPadres(TreeView trv, int otPadre, DataTable datos)
    {
        if (datos.Rows.Count > 0)
        { 
            foreach (DataRow dr in datos.Select("OTPadre='"+ otPadre+"'"))
            {
                TreeNode nodoPadre = new TreeNode();
                nodoPadre.Text = dr["OTPadre"].ToString();
                trv.Nodes.Add(nodoPadre);
                cargarSubOts(ref nodoPadre, int.Parse(dr["OTHija"].ToString()), datos);
            }
        }
        return trv;
    }

    private void cargarSubOts(ref TreeNode nodoPadre, int otPadre, DataTable datos)
    {
        DataRow[] otHijas = datos.Select("OTPadre='" + otPadre +"'");
        foreach (DataRow drow in otHijas)
        {
            TreeNode hija = new TreeNode();
            hija.Text = drow["OTHija"].ToString();
            nodoPadre.Nodes.Add(hija);
            cargarSubOts(ref hija, int.Parse(drow["OTHija"].ToString()), datos);
        }
    }

This did it. I leave it here in case anyone needs it. Thanks again.

Answer 1

The main issue in your code that you are not looking for the child parent in the tree view to add it under , you add them all under main parent.

i made some changes to your code hopefully it work straight forward or with minor changes at your side:

        if (arb.Rows.Count > 0)
        {
            TreeNode MainNode = new TreeNode();

            string otPadre = arb.Rows[0][0].ToString();
            int nivel = 0;

            MainNode.Text = otPadre;
            trvOTHs.Nodes.Add(MainNode);

            for (int i = 0; i < arbolSub.Rows.Count; i++)
            {        

            TreeNode child = new TreeNode();
            child.Text = row["OT Hija"].ToString();

            if (arbolSub.Rows[i]["OT Padre"].ToString() == otPadre)
            {
                MainNode.Nodes.Add(child);  
            }
            else
            {
                FindParent(MainNode, row["OT Padre"].ToString(), child);
            }

            }

            trvOTHs.ExpandAll();
        }

this function to find the parent node :

    private void FindParent(TreeNode ParentNode, string Parent, TreeNode ChildNode)
    {
        foreach (TreeNode node in ParentNode.Nodes)
        {
            if (node.Text.ToString() == Parent)
            {
                node.Nodes.Add(ChildNode); 
            }
            else
            {
                FindParent(node, Parent, ChildNode);
            }
        }
    }