Question

I have the Xaml which should basically bind a set of ContextualButtons for a selected tab’s viewmodel to the ItemsSource property of the ToolBar. For some reason, this binding is not actually occuring unless I use Snoop to inspect the element manually…It seems that the act of snooping the element is somehow requerying the binding somehow.

Does anyone know what I might be doing wrong here? This behavior is the same if I use a Listbox as well, so I know it is something that I am doing incorrectly…but I am not sure what.

SelectedView is a bound property to the selected view from a Xam Tab control.

XAML

<ToolBar DataContext="{Binding SelectedView.ViewModel}"
     ItemsSource="{Binding ContextualButtons}" >     
     <ToolBar.ItemTemplate>
      <DataTemplate>
<!--       <Button ToolTip="{Binding Name}"-->
<!--         Command="{Binding Command}">-->
<!--        <Button.Content>-->
<!--         <Image Width="32" Height="32" Source="{Binding ImageSource}"/>-->
<!--        </Button.Content>-->
<!--       </Button>-->
       <Button Content="{Binding Name}"/>
      </DataTemplate>
     </ToolBar.ItemTemplate>

    </ToolBar>

Code

      public class TestViewModel : BaseViewModel, IBulkToolViewModel
      {


        public TestViewModel()
        {
          ContextualButtons = new ObservableCollection<IContextualButton>()
                                {
                                  new ContextualButton("Test Button",
                                                       new DelegateCommand<object>(
                                                         o_ => Trace.WriteLine("Called Test Button")), String.Empty)
                                };
        }

        public string Key { get; set; }
        private ObservableCollection<IContextualButton> _contextualButtons;
        public ObservableCollection<IContextualButton> ContextualButtons
        {
          get { return _contextualButtons; }
          set
          {
            if (_contextualButtons == value) return;
            _contextualButtons = value;
            //OnPropertyChanged("ContextualButtons");
          }
        }

      }

      public partial class TestView : UserControl, IBulkToolView
      {
        public TestView()
        {
          InitializeComponent();

        }


        public IBulkToolViewModel ViewModel { get; set; }

      }
      public class ContextualButton : IContextualButton
      {
        private string _name;
        public string Name
        {
          get { return _name; }
          set { _name = value; }
        }

        public ICommand Command { get; set; }
        public string ImageSource { get; set; }

        public ContextualButton(string name_, ICommand command_, string imageSource_)
        {
          Name = name_;
          Command = command_;
          ImageSource = imageSource_;
        }
      }

  public class BulkToolShellViewModel : BaseViewModel, IBaseToolShellViewModel, IViewModel 
  {

    private IBulkToolView _selectedView;
    public IBulkToolView SelectedView
    {
      get
      {
        return _selectedView;
      }
      set
      {
        if (_selectedView == value) return;
        _selectedView = value;
        OnPropertyChanged("SelectedView");

      }
    }
  public ObservableCollection<IBulkToolView> Views { get; set; }

    public DelegateCommand<object> AddViewCommand { get; private set; }
    public DelegateCommand<object> OpenPortfolioCommand { get; private set; }
    public DelegateCommand<object> SavePortfolioCommand { get; private set; }
    public DelegateCommand<object> GetHelpCommand { get; private set; }


    public BulkToolShellViewModel(ObservableCollection<IBulkToolView> views_)
      : this()
    {
      Views = views_;
    }

    public BulkToolShellViewModel()
    {
      Views = new ObservableCollection<IBulkToolView>();
      AddViewCommand = new DelegateCommand<object>(o_ => Views.Add(new TestView
                                                                     {
                                                                       ViewModel = new TestViewModel()
                                                                     }));
      OpenPortfolioCommand = new DelegateCommand<object>(OpenPortfolio);
      SavePortfolioCommand = new DelegateCommand<object>(SavePortfolio);
      GetHelpCommand = new DelegateCommand<object>(GetHelp);
    }

    private void GetHelp(object obj_)
    {

    }

    private void SavePortfolio(object obj_)
    {

    }

    private void OpenPortfolio(object obj_)
    {

    }

    public event PropertyChangedEventHandler PropertyChanged;
    public void RaisePropertyChanged()
    {
      throw new NotImplementedException();
    }

    public void RaisePropertyChanged(string propertyName)
    {
      throw new NotImplementedException();
    }

    public string this[string columnName]
    {
      get { throw new NotImplementedException(); }
    }

    public string Error { get; private set; }
    public AsyncContext Async { get; private set; }
    public XmlLanguage Language { get; private set; }
    public string Key { get; set; }


  }

Thanks!

Answer 1

Why does BulkToolShellViewModel have its own PropertyChanged event along with RaisePropertyChanged methods that do nothing? Shouldn’t it inherit this functionality from BaseViewModel? Perhaps the UI is attaching to BulkToolShellViewModel.PropertyChanged rather than BaseViewModel.PropertyChanged and is never being notified of changes.