Create Hierarchy with Linq

Question

I was reading this to try and create a hierarchy 2 levels deep in WPF, C# with Linq to Sql using 1 table. The table does not have a parent or child key relationship. How can this be created in a treeview?

http://www.scip.be/index.php?Page=ArticlesNET09

I am trying to make paper the 1st level and title the second of the tree.

DC12
    Once Around     
    Second Around
    New Age#3
    Third Around
DC13
    New Age

DC14
    Rock & Roll
    Rock & Roll #2
DC15
    Top 5
    New Age #2

Here are the class'

public class Parent
{
    public string Paper { get; set; }
    public IEnumerable<Child> Readings { get; set; }
}

public class Child
{
    public string Paper { get; set; }
    public string Title { get; set; }
    public IEnumerable<Book> Books { get; set; }
}

Answer 1

try this simple code (sample from my project) :

1 .aspx

<table>
   <tr>
      <td>
         <asp:TreeView ID="HierarchyTreeView" ExpandDepth="3" PopulateNodesFromClient="true"
                                                            ForeColor="Blue" BackColor="ButtonFace" ShowLines="true" ShowExpandCollapse="true"
                                                            runat="server" OnTreeNodePopulate="HierarchyTreeView_TreeNodePopulate" />
      </td>
   </tr>
 </table>

2 .cs

    protected void Page_Load(object sender, EventArgs e){
    this.PopulateRootLevel();
    }

    private void PopulateRootLevel()
    {
        DataTable _dataTable = this.GetDataTable(ApplicationConfig.ConnString, "sp_PopulateRootLevel", "parentID", String.Empty);
        this.PopulateNodes(_dataTable, this.HierarchyTreeView.Nodes);
    }

    private void PopulateSubLevel(String _parentID, TreeNode _parentNode)
    {
        DataTable _dataTable = this.GetDataTable(ApplicationConfig.ConnString, "sp_PopulateRootLevel", "parentID", _parentID);
        this.PopulateNodes(_dataTable, _parentNode.ChildNodes);
    }

    protected void HierarchyTreeView_TreeNodePopulate(object sender, TreeNodeEventArgs e)
    {
        PopulateSubLevel(e.Node.Value.ToString(), e.Node);
    }

    private void PopulateNodes(DataTable _dataTable, TreeNodeCollection _nodes)
    {
        foreach (DataRow _dataRow in _dataTable.Rows)
        {
            TreeNode _treeNode = new TreeNode();
            _treeNode.Text = _dataRow["EmpName"].ToString();
            _treeNode.Value = _dataRow["EmpNumb"].ToString();

            if (_dataRow["FgActive"].ToString() == "Y")
                _nodes.Add(_treeNode);

            _treeNode.PopulateOnDemand = ((int)(_dataRow["ChildNodeCount"]) > 0);
        }
    }

public DataTable GetDataTable(String _prmConnString, String _prmStoreProcedure, String _prmField, String _prmValue)
    {
        DataTable _result = new DataTable();

        string[] _field = _prmField.Split('|');
        string[] _value = _prmValue.Split('|');

        try
        {
            SqlConnection _conn = new SqlConnection(_prmConnString);
            SqlCommand _cmd = new SqlCommand();
            _cmd.CommandType = CommandType.StoredProcedure;
            _cmd.Parameters.Clear();
            _cmd.Connection = _conn;
            _cmd.CommandTimeout = 180;
            _cmd.CommandText = _prmStoreProcedure;
            for (int i = 0; i < _field.Count(); i++)
                _cmd.Parameters.AddWithValue("@" + _field[i], _value[i]);

            SqlDataAdapter _da = new SqlDataAdapter();
            _da.SelectCommand = _cmd;
            _da.Fill(_result);
        }
        catch (Exception ex)
        {
        }

        return _result;
    }

3 .sql

CREATE PROC dbo.sp_PopulateRootLevel(@parentID VARCHAR(50))  
AS   
SELECT a.EmpNumb,a.EmpName,a.CompanyID, b.JobTitleName + ' - ' + c.JobLevelName AS JobTitleLevel,  
(SELECT COUNT(*) FROM dbo.MsEmployee WHERE EmpNumbParent = a.EmpNumb) AS ChildNodeCount,a.FgActive   
FROM dbo.MsEmployee a   
LEFT JOIN dbo.MsJobTitle b ON a.JobTitle = b.JobTitleId  
LEFT JOIN dbo.MsJobLevel c ON a.JobLevel = c.JobLevelId  
WHERE a.EmpNumbParent = @parentID