I'm beginner for C# and WPF.

When I tried to figure out how to bind data to treeview, I find a example in Microsoft learn, the link is

I code the objects with my limited C# knowledge, as below.

Objects: ListLeagueList

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Collections.ObjectModel;

namespace Treeview01
{
    public class ListLeagueList : ObservableCollection<League>
    {
        public ListLeagueList() : base()
        {
            Add(new League("League A"));
            Add(new League("League B"));
            Add(new League("League C"));
        }
    }
}

Objects: League

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Collections.ObjectModel;

namespace Treeview01
{
    public class League
    {
        public string Name { get; set; }

        List<Division> Divisions  = new List<Division>();
        public League(string name) //: base()
        {
            Name = name;
            Divisions.Add(new Division("DivisionA"));
            Divisions.Add(new Division("DivisionB"));
            Divisions.Add(new Division("DivisionC"));
        }
        private League()
        {
        }
    }
}

Objects: Division

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Collections.ObjectModel;

namespace Treeview01
{
    public class Division
    {
        public string Name { get; set; }

        List<Team> Teams = new List<Team>();
        public Division(string name) //: base()
        {
            Name = name;
            Teams.Add(new Team("Bear"));
            Teams.Add(new Team("Rocket"));
        }
        private Division()
        {
        }

    }
}

Objects: Team

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Treeview01
{
    public class Team
    {
        public string Name { get; set; }

        public Team(string name)
        {
            Name = name;
        }

        private Team()
        {
        }
    }
}

XAML:

<Window x:Class="Treeview01.Window1"
      xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
      xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
      Title="HierarchicalDataTemplate Sample"
      xmlns:src="clr-namespace:Treeview01">
        <DockPanel>
            <DockPanel.Resources>
                <src:ListLeagueList x:Key="MyList"/>
    
                <HierarchicalDataTemplate DataType    = "{x:Type src:League}"
                                    ItemsSource = "{Binding Path=Divisions}">
                    <TextBlock Text="{Binding Path=Name}"/>
                </HierarchicalDataTemplate>
    
                <HierarchicalDataTemplate DataType    = "{x:Type src:Division}"
                                    ItemsSource = "{Binding Path=Teams}">
                    <TextBlock Text="{Binding Path=Name}"/>
                </HierarchicalDataTemplate>
    
                <DataTemplate DataType="{x:Type src:Team}">
                    <TextBlock Text="{Binding Path=Name}"/>
                </DataTemplate>
                
            </DockPanel.Resources>
    
            <Menu Name="menu1" DockPanel.Dock="Top" Margin="10,10,10,10">
                <MenuItem Header="My Soccer Leagues"
                      ItemsSource="{Binding Source={StaticResource MyList}}" />
            </Menu>
    
            <TreeView>
                <TreeViewItem ItemsSource="{Binding Source={StaticResource MyList}}" Header="My Soccer Leagues" />
            </TreeView>
    
        </DockPanel>
    </Window>

XAML.CS:

using System.Windows;

namespace Treeview01
{
    /// <summary>
    /// Interaction logic for Window1.xaml
    /// </summary>
    public partial class Window1 : Window
    {
        public Window1()
        {
            InitializeComponent();
        }

    }
}

With the code above, only the first level data is represented, as the picture below.

Please check and correct my code. Thank you very much!

CodePudding user response：

Divisions and Teams could not be recognized in Xaml , because they are not public properties.

Devisions

public List<Division> Divisions { set; get; } = new List<Division>();

Teams

public List<Team> Teams { set; get; } = new List<Team>();