WPF-TreeView DataBinding in MVVM

Question

I just try to implement simple MVVM-model with WPF-TreeView with DataBinding. But I found some problems with it and hope, that someone of you can help me with it.

I have Model, where I defind my own class:

public class ItemOfWorld : INotifyPropertyChanged
{
    #region Fields
    private ObservableCollection<ItemOfWorld> _Items;
    private string _Name;
    private ItemOfWorld _Parent;
    #endregion

    #region FieldDeclaration
    public ObservableCollection<ItemOfWorld> Items 
    { 
        get
        {
            return _Items;
        }
        set
        {
            _Items = value;
            OnPropertyChanged("Items");
        }
    }

    public string Name
    {
        get
        {
            return _Name;
        }
        set 
        {
            _Name = value;
            OnPropertyChanged("Name");
        }
    }

    public ItemOfWorld Parent
    {
        get
        {
            return _Parent;
        }
        set
        {
            _Parent = value;
            OnPropertyChanged("Parent");
        }
    }

    #endregion

    public ItemOfWorld(ItemOfWorld parent)
    {
        Items = new ObservableCollection<ItemOfWorld>();
        Parent = parent;
    }

    #region INotifyPropertyChanged Members

    public event PropertyChangedEventHandler PropertyChanged;

    private void OnPropertyChanged(string propertyName)
    {
        PropertyChangedEventHandler handler = PropertyChanged;

        if (handler != null)
        {
            handler(this, new PropertyChangedEventArgs(propertyName));
        }
    }

    #endregion
}

public class MyWorld:ItemOfWorld
{
    public MyWorld():base(null)
    {
        Name = "MyWorld";
        Items.Add(new Ions(this));
    }
}

public class Ions : ItemOfWorld
{
    public Ions(ItemOfWorld parent)
        : base(parent)
    {
        Name = "Ions";
        Parent = parent;
    }
}

public class Molecules : ItemOfWorld
{
    public Molecules(ItemOfWorld parent)
        : base(parent)
    {
        Name = "Molecules";
        Parent = parent;
    }
}

I have a ViewModel, where I create MyWorld class:

internal class ItemsOfWorldViewModel
{
    #region Fields
    private ItemOfWorld _MyItem;
    #endregion

    #region FieldDeclaration
    public ItemOfWorld MyItem
    {
        get
        {
            return _MyItem;
        }
        set
        {
            _MyItem = value;
        }
    }
    #endregion



    public ItemsOfWorldViewModel()
    {
        MyItem = new MyWorld();
    }

}

And, finally, I have a View with TreeView toolbox, with simple code-behind:

 ItemsOfWorldViewModel myworld=new ItemsOfWorldViewModel();
 TreeView1.DataContext = myworld;

My question is: How can I show in my TreeView my hierarchy without using local-sources?

-MyWorld
     -->Ions
     -->Molecules

If I implement simple TextBlock it is works without any additional libraries and local-sources, just simple DataContext in code-behind and in XAML:

<TextBox x:Name="TextBlock2" Text="{Binding MyItem.Name}"></TextBox>

Answer 1

Use HierarchicalDataTemplate as your TreeView.ItemTemplate

    <TreeView ItemsSource="{Binding MyItem.Items}">
            <TreeView.Resources>
                <HierarchicalDataTemplate DataType="{x:Type local:ItemOfWorld }" ItemsSource = "{Binding Path=Items}">
                    <TextBlock Text="{Binding Path=Name}"/>
                </HierarchicalDataTemplate>
            </TreeView.Resources>
        </TreeView>