ASP.NET Tree View out of Sql Binding

Question

I got a Categorie Table with a column for the Tree View in my Database which I want to display as a Tree View.

My TreeView Column Looks like the following. (I Hope you understand)

0001.
0001.0001.
0001.0002.
0001.0002.0001.
0001.0002.0002.
0001.0003.
0002.
...
...
...

Is this possible to be displayed in a asp:TreeView? Or what other way can I use to display this?

The Database already existed I'm just designing the website & can't do much in the database.

EDIT:

I tried the first Solutions and now I got this. Image

But I don't want to display the number, just the name and the number just as value invisible for me to use when I click on it.

Answer 1

Try something like following :

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace WindowsFormsApplication64
{
    public partial class Form1 : Form
    {
        DataTable dt = null;
        public Form1()
        {
            InitializeComponent();

            dt = new DataTable();
            dt.Columns.Add("Index", typeof(string));
            dt.Columns.Add("Value", typeof(string));

            dt.Rows.Add(new object[] { "0001.", "aaaa"});
            dt.Rows.Add(new object[] { "0001.0001.", "bbbb"});
            dt.Rows.Add(new object[] { "0001.0002.", "cccc"});
            dt.Rows.Add(new object[] { "0001.0002.0001.", "dddd"});
            dt.Rows.Add(new object[] { "0001.0002.0002.", "eeee"});
            dt.Rows.Add(new object[] { "0001.0003.", "ffff"});
            dt.Rows.Add(new object[] { "0002.", "gggg" });

            new Index(dt);

            MakeTreeRecursive(0, Index.indexes, null);
            treeView1.ExpandAll();

        }
        public void MakeTreeRecursive(int level, List<Index> rows, TreeNode parent)
        {
            TreeNode child = null;

            var groups = rows
                .OrderBy(x => x.paragraphs[level])
                .GroupBy(x => x.paragraphs[level]);

            foreach (var group in groups)
            {
                child = new TreeNode(group.Key);
                if (parent == null)
                {
                    treeView1.Nodes.Add(child);
                }
                else
                {
                    parent.Nodes.Add(child);
                }

                foreach (Index node in group.Where(x => x.paragraphs.Count == level + 1))
                {
                    child.Nodes.Add(node.row.Field<string>("Value"));
                }
                List<Index> descendants = group.Where(x => x.paragraphs.Count > level + 1).ToList();
                if (descendants.Count > 0)
                {
                    MakeTreeRecursive(level + 1, descendants, child);
                }

            }
        }
    }
    public class Index
    {
        public static List<Index> indexes { get; set; }
        public List<string> paragraphs { get; set; }
        public DataRow row { get; set; }

        public Index() { }
        public Index(DataTable dt)
        {
            Index.indexes =  dt.AsEnumerable()
                .Select(x => new Index() {
                    row = x,
                    paragraphs = x.Field<string>("Index")
                    .Split(new char[] {'.'}, StringSplitOptions.RemoveEmptyEntries)
                    .Select(y=> y).ToList()
                }).ToList();

        }
    }
}

Here is solution if you only want the text

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        DataTable dt = null;
        public Form1()
        {
            InitializeComponent();

            dt = new DataTable();
            dt.Columns.Add("Index", typeof(string));
            dt.Columns.Add("Value", typeof(string));

            dt.Rows.Add(new object[] { "0001.", "aaaa" });
            dt.Rows.Add(new object[] { "0001.0001.", "bbbb" });
            dt.Rows.Add(new object[] { "0001.0002.", "cccc" });
            dt.Rows.Add(new object[] { "0001.0002.0001.", "dddd" });
            dt.Rows.Add(new object[] { "0001.0002.0002.", "eeee" });
            dt.Rows.Add(new object[] { "0001.0003.", "ffff" });
            dt.Rows.Add(new object[] { "0002.", "gggg" });

            new Index(dt);

            MakeTreeRecursive(0, Index.indexes, null);
            treeView1.ExpandAll();

        }
        public void MakeTreeRecursive(int level, List<Index> rows, TreeNode parent)
        {
            TreeNode child = null;

            var groups = rows
                .OrderBy(x => x.paragraphs[level])
                .GroupBy(x => x.paragraphs[level]);

            foreach (var group in groups)
            {
                Index root = group.OrderBy(x => x.paragraphs.Count).First();
                child = new TreeNode(root.row.Field<string>("Value"));

                List<Index> descendants = group.Where(x => x.paragraphs.Count > level + 1).ToList();
                if (descendants.Count()  > 0)
                {
                    MakeTreeRecursive(level + 1, descendants, child);
                }
                if (parent == null)
                {
                    treeView1.Nodes.Add(child);
                }
                else
                {
                    parent.Nodes.Add(child);
                }
            }
        }
    }
    public class Index
    {
        public static List<Index> indexes { get; set; }
        public List<string> paragraphs { get; set; }
        public DataRow row { get; set; }

        public Index() { }
        public Index(DataTable dt)
        {
            Index.indexes = dt.AsEnumerable()
                .Select(x => new Index()
                {
                    row = x,
                    paragraphs = x.Field<string>("Index")
                    .Split(new char[] { '.' }, StringSplitOptions.RemoveEmptyEntries)
                    .Select(y => y).ToList()
                }).ToList();

        }
    }
}