How to build nested treeview in C#?

Question

I am using dapper, asp.net web api and want to show data in treeview. For this, I have 2 models that currently looks like below. Database table mapping:

public c         


        

Answer 1

You don't need a treeview. You can use a DataTable with 1st column being a boolean

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
    {
        public Form1()
        {
            InitializeComponent();
            dataGridView1.AllowUserToAddRows = false;

            List<Zones> zones = new List<Zones>() {
                new Zones() { 
                    Id = "AllZone", Name = "AllZone", Childrens = new List<Zones>() {
                        new Zones() { 
                            Id = "SZ001", Name = "All Stores", Childrens = new List<Zones>() {
                                new Zones() { Id = "1", Name = "Express", Childrens = null},
                                new Zones() { Id = "2", Name = "National", Childrens = null},
                                new Zones() { Id = "3", Name = "Metro", Childrens = null},
                                new Zones() { Id = "4", Name = "Scotland National", Childrens = null},
                                new Zones() { Id = "5", Name = "Scotland Express", Childrens = null},
                                new Zones() { Id = "6", Name = "UK London Metro", Childrens = null}
                            }
                        }
                    }
                }
            };

            DataTable dt = new DataTable();
            dt.Columns.Add("Enabled", typeof(Boolean));
            dt.Columns.Add("ID", typeof(string));
            dt.Columns.Add("Name", typeof(string));
            dt.Columns.Add("Parent", typeof(string));
            dt.Columns["Parent"].AllowDBNull = true;

            Zones.GetChildren(dt, zones, "NULL");
            dt = dt.AsEnumerable().OrderBy(x => x.Field<string>("ID")).CopyToDataTable();
            dataGridView1.DataSource = dt;
        }
    }
    public class Zones
    {
        public string Id { get; set; }
        public string Name { get; set; }
        public List<Zones> Childrens { get; set; }

        public static void GetChildren(DataTable dt, List<Zones> children, string parent)
        {
            foreach (Zones child in children)
            {
                dt.Rows.Add(new object[] { false, child.Id, child.Name, parent });
                if (child.Childrens != null)
                {
                    GetChildren(dt, child.Childrens, child.Id);
                }
            }
        }

    }
}

Answer 2

Create a method in Zones model

public void PrintPretty(string indent, bool last)
    {
        Console.Write(indent);
        if (last)
        {
            Console.Write("|-");
            indent += "  ";
        }
        else
        {
            Console.Write("|-");
            indent += "| ";
        }
        Console.WriteLine(Name);

        for (int i = 0; i < Children.Count; i++)
            Children[i].PrintPretty(indent, i == Children.Count - 1);
    }

then rename the zones model class to childzone

public class childzones
{
    public string model_zone_id { get; set; }
    public string model_zone_name { get; set; }
    public string model_zone_parent_id { get; set; }
}

because class names should not be equal for generating treeNode.

You can use the same Zones class like this

 public class Zones
    {

        public Zones()
        {
            Children = new List<Zones>();
        }
        public string Id { get; set; }
        public string Name { get; set; }
        public List<Zones> Children { get; set; }

        public void PrintPretty(string indent, bool last)
        {
            Console.Write(indent);
            if (last)
            {
                Console.Write("|-");
                indent += "  ";
            }
            else
            {
                Console.Write("|-");
                indent += "| ";
            }
            Console.WriteLine(Name);

            for (int i = 0; i < Children.Count; i++)
                Children[i].PrintPretty(indent, i == Children.Count - 1);
        }

    }

Finally you will get a Model like this

static void Main(string[] args)
        {

            Zones node1 = new Zones()
            {
                Name = "Root",
                Id = "1",
                Children = {
                    new Zones() {
                        Name = "BranchA",
                       Id = "1",
                        Children = {
                            new Zones() {
                                Name = "Siblings1",
                                 Id = "1",
                                Children = {
                                    new Zones() {
                                        Name = "subChild1",
                                         Id = "1",
                                        Children = {
                                        }
                                    },
                                    new Zones() {
                                        Name = "subchild2",
                                         Id = "1",
                                        Children= {
                                        }
                                    }
                                }

                            },
                            new Zones() {
                                Name = "Siblings2",
                                 Id = "1",
                                Children = {

                                }
                            }
                        }
                    },
                    new Zones() {
                        Name = "BranchB",
                         Id = "1",
                        Children = {
                            new Zones() {
                                Name = "Sibilings1",
                                 Id = "1",
                                Children = {

                                }
                            }
                        }
                    }
                }
            };
            node1.PrintPretty("", true);

}

Output

|-Root
  |-BranchA
  | |-Siblings1
  | | |-subChild1
  | | |-subchild2
  | |-Siblings2
  |-BranchB
    |-Sibilings1