ReactiveUI - master/detail binding - de-select current record - xaml

Question

I'm trying to implement master/detail using ReactiveUI for a list of attachments. Here's a simplified version of my view model:
public class AttachmentsViewModel : ReactiveObject, ISupportsActivation
{
private ReactiveList<Attachment> _attachments;
public ReactiveList<Attachment> Attachments
{
get => _attachments;
set => this.RaiseAndSetIfChanged( ref _attachments, value );
}
private IReactiveDerivedList<AttachmentViewModel> _attachmentViewModels;
public IReactiveDerivedList<AttachmentViewModel> AttachmentViewModels
{
get => _attachmentViewModels;
set => this.RaiseAndSetIfChanged(ref _attachmentViewModels, value );
}
private AttachmentViewModel _selected;
public AttachmentViewModel Selected
{
get => _selected;
set => this.RaiseAndSetIfChanged( ref _selected, value );
}
}
In my view, I have a ListView and a set of controls to let the user edit properties (e.g. a TextBox called AttachmentName). Here's what I would do in the view, based on the view model above:
public class AttachmentsView : IViewFor<AttachmentsViewModel>
{
public AttachmentsView()
{
InitializeComponent();
this.WhenActivated( d => {
this.OneWayBind( ViewModel, vm => vm.AttachmentViewModels, v => v.List.ItemsSource ).DisposeWith( d );
this.Bind( ViewModel, vm => vm.Selected, v => v.List.SelectedItem ).DisposeWith( d );
this.Bind( ViewModel, vm => vm.Selected.Name, v => v.AttachmentName.Text ).DisposeWith( d );
}
}
}
All of this works as expected, when I click on a row in the ListView, the controls in my panel change accordingly.
However, when I de-select the currently selected item, AttachmentName still displays the old value (instead of showing nothing). I'm assuming that the linq expression does not fire the property changed event because the binding is more than one property deep?
Is there any way around this? Maybe there's another way to achieve master-detail navigation/editing?

Answer 1

You can observe in your view the SelectedItem and change the AttachmentName:
this.WhenAnyValue(x => x.ViewModel.Selected).Where(x => x == null)
.Subscribe(selected => AttachmentName.Text == "").DisposeWith(d);