v11-Prev 5 - After Upgrading Prism Module Region Fails Inside of ItemsControl

[DamianSuess]

Issue

After upgrading to Avalonia v11-Preview5, Prism Modules can fail to register a region defined in XAML.

The error is being thrown in ItemsControlRegionAdapter.Adapt(IRegion region, ItemsControl regionTarget) when it attempts to set regionTarget.Items = region.Views;. Which is equivalent to Avalonia.Collections.AvaloniaList<object> = Prism.Regions.ViewsCollection. To address this, IViewsCollection may need to inherit IList (by why all a sudden?)

  <!-- DummyModuleView2.axaml -->
  <ItemsControl prismRegions:RegionManager.RegionName="ListRegion"></ItemsControl>

Reproduce

1. Pull latest Develop branch
2. Set sample app, ModuleSampleApp as Startup Project
3. Run the code
4. The above error will be thrown before the window renders

Research

Currently, I'm looking into what changed in the architecture to warrant this modification. This could be why the sample app, ViewDiscovery, is also failing to operate correctly

Error Message:

Prism.Regions.Behaviors.RegionCreationException: 'An exception occurred while creating a region with name 'ListRegion'. The exception was: System.ArgumentException: Collection implements INotifyCollectionChanged but not IList. (Parameter 'source')

Call Stack:

This exception was originally thrown at this call stack:
    Avalonia.Controls.ItemsSourceView.ItemsSourceView(System.Collections.IEnumerable) in ItemsSourceView.cs
    Avalonia.Controls.ItemsSourceView.GetOrCreate(System.Collections.IEnumerable) in ItemsSourceView.cs
    Avalonia.Controls.ItemsControl.OnPropertyChanged(Avalonia.AvaloniaPropertyChangedEventArgs) in ItemsControl.cs
    Avalonia.Animation.Animatable.OnPropertyChangedCore(Avalonia.AvaloniaPropertyChangedEventArgs) in Animatable.cs
    Avalonia.Controls.ItemsControl.Items.set(System.Collections.IEnumerable) in ItemsControl.cs
    Prism.Regions.ItemsControlRegionAdapter.Adapt(Prism.Regions.IRegion, Avalonia.Controls.ItemsControl) in ItemsControlRegionAdapter.cs
    Prism.Regions.RegionAdapterBase<T>.Initialize(T, string) in RegionAdapterBase.cs
    Prism.Regions.RegionAdapterBase<T>.Prism.Regions.IRegionAdapter.Initialize(object, string) in RegionAdapterBase.cs
    Prism.Regions.Behaviors.DelayedRegionCreationBehavior.CreateRegion(Avalonia.AvaloniaObject, string) in DelayedRegionCreationBehavior.cs

References

• AvaloniaUI/Avalonia@3195df0
• https://github.com/AvaloniaUI/Avalonia/blob/master/src/Avalonia.Controls/ItemsControl.cs

[DamianSuess]

This item needs researched. Even adding IList to our class appears to be overkill.

Overall, this PR is blocking the release of Preview-5

[DamianSuess]

Fixed issue by performing a cast expression on:

regionTarget.Items = region.Views as Avalonia.Collections.AvaloniaList<object>;