How can I get data binding to work properly with a DependencyProperty having an ObservableCollection property?

[SetTrend]

My WPF window's view model resembles the following:

public class ViewModel : INotifyPropertyInfo
{
  private ObservableCollection<MyItems> _myItems;

  public  ObservableCollection<MyItems> MyItemCollection
  {
    get => _myItems;

    set =>
    {
      _myItems = value;
      PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(MyItemCollection)));
    }
  }
}

My WPF window's code-behind class resembles this:

public partial class MainWindow : Window
{
  public static readonly DependencyProperty VMProperty = DependencyProperty.Register("VM"
                                                                                    , typeof(ViewModel)
                                                                                    , typeof(MainWindow)
                                                                                    );

  public ViewModel VM
  {
    get => (ViewModel)GetValue(VMProperty);
    set => SetValue(VMProperty, value);
  }
}

Now, wenn I bind an ItemsControl.ItemSource to VM.MyItemCollection – nothing happens when items in the ObservableCollection member of my view model are updated.

What am I doing wrong?

Here's an excerpt of my MainWindow.xaml:

<Window x:Class="GaqlReplApplication.WpfWindows.Main.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        mc:Ignorable="d" x:Name="MainWin"
				DataContext="{Binding RelativeSource={RelativeSource Mode=Self}}"
				>
  <ListView ItemsSource="{Binding Path=VM.MyItemCollection}"/>
</Window>

[miloush]

Do you have a small repro project?

[lindexi]

I also think that this problem should not occur under normal use. That I need the repro code.

[SetTrend]

I will prepare an MRE in the next few days, using my current application and strip off all redundant code. Please bear with me.

[SetTrend]

Here's the MRE now:

https://github.com/SetTrend/WpfDataBindingMRE

These Three Issues From The MRE Need A Remedy

1. Why doesn't the FileMruList MenuItem data binding automatically create the corresponding menu items when the collection is updated?
2. How do I assign a command to the dynamically created menu items for them to eventually work?
3. What's causing the XAML binding failure depicted in the screenshot?

[miloush]

1. Because you are updating different collection than the controls are bound to. In Window_Loaded, you are setting Settings.Preferences to a new instance, so FileMruList => Settings.Preferences.FileMruList now points to a brand new collection. You either need to set Settings.Preferences before the InitializeComponent() call, or, you will have to make sure changes to FileMruList instance are announced via property change notification.

3. Don't worry about the alignment binding failure, that comes from the template - it is not caused by your code and does not affect you.

[miloush]

For 2., the command needs to be set on the container, so you can do:

<MenuItem.ItemContainerStyle>
	<Style TargetType="MenuItem">
		<Setter Property="Command" Value="{StaticResource ResourceKey=FileMruCmd}" />
	</Style>
</MenuItem.ItemContainerStyle>

This will not affect your ClearCmd because local values have precedence over values from style.