Problem to update hierarchical data and display it in treeView.

[hdv212]

Hi i have a simple app which display emplyees organization chart from northwind database. here is my code to accomplish this :

private void btnLoadData_Click(object sender, EventArgs e)
{
this.treeView1.Nodes.Clear();

  this.\_dtEmployees = this.GetEmployees();
  this.FillHieraricalData(this.\_dtEmployees, this.treeView1, "LastName", "EmployeeID", "ReportsTo");
  this.treeView1.ExpandAll();

}

private DataTable GetEmployees()
{
DataTable dt = new DataTable();

  using (SqlConnection con = new SqlConnection(Properties.Settings.Default.NorthwindConnectionString))
  {
    SqlCommand cmd = con.CreateCommand();
    cmd.CommandText = "select \* from employees";
    con.Open();
    dt.Load(cmd.ExecuteReader());
    con.Close();
  }

  return dt;

}

private void FillHieraricalData(DataTable dt, TreeView treeView, string infoColumnName,
string pkColumnName, string parentColumnName)
{
TreeNode node = null;
foreach (DataRow row in dt.Rows)
{
node = new TreeNode(row[infoColumnName].ToString());
node.Tag = row[pkColumnName];

    if (row\[parentColumnName\] != DBNull.Value)
    {
      List<TreeNode> foundNodes = new List<TreeNode>();

      // search over treeView nodes to found parent of row (if exists)
      SearchNodeInTreeView(treeView.Nodes, Convert.ToInt32(row\[parentColumnName\]), foundNodes);
      if (foundNodes.Count > 0)
        foundNodes\[0\].Nodes.Add(node);
    }
    else // if row parent does not exists, then it's parent itself (or it's root), it should add to level 0 of treeView
      treeView.Nodes.Add(node);
  }

}

// this method search in treeView.Nodes to find specific nodes base on 'value'
private void SearchNodeInTreeView(TreeNodeCollection nodesToSearch, int value, List<TreeNode> foundNodes)
{
for (int i = 0; i < nodesToSearch.Count; i++)
{
if (Convert.ToInt32(nodesToSearch[i].Tag) == value)
foundNodes.Add(nodesToSearch[i]);

    //Recursively search in the child nodes        
    SearchNodeInTreeView(nodesToSearch\[i\].Nodes, value, foundNodes);
  }

}

However, when i update data in memory (via dataTable) and redisplay data in treeView, the row that has been modfied has been removed from treeView and not display. for example, when i change 'Reports To' of any employee, that employee does not display in treeView! here

[Mycroft Holmes]

You are putting the row id into the tag property

node.Tag = row[pkColumnName];

But I don't see where you find that row to update the record when editing. You may be updating row[0] all the time. I have been known to stick the entire row object into the tag property.

node.Tag = row;

Never underestimate the power of human stupidity RAH

[hdv212]

Thanks Mycroft but still i have the same problem.