I have a bound property on a class, Foo which is defined similar to as follows (edited for clarity),
public class Foo : INotifyPropertyChanged
{
public Foo()
{
// This should notify when IsHidden changes?
MyApp.ViewModel.HiddenCategories.CollectionChanged += (s, e) => {
this.NotifyPropertyChanged("IsHidden");
};
}
public CategoryId Category { get; set; }
// IsHidden depends on a `global' ObservableCollection object on the ViewModel
public bool IsHidden
{
get { return MyApp.ViewModel.HiddenCategories.Contains(this.Category); }
}
// IsHidden is toggled by adjusting the global ObservableCollection - how to notify the UI?
public void ToggleHidden()
{
if (this.IsHidden)
MyApp.ViewModel.HiddenCategories.Remove(this.Category);
else
MyApp.ViewModel.HiddenCategories.Add(this.Category);
}
#region INotifyPropertyChanged members
...
}
The ViewModel has the following defined on it,
public class FooRegion
{
public string RegionName { get; set; }
// Foos is bound in the top ListBox DataTemplate
// Each Foo has properties bound in the sub ListBox DataTemplate
public ObservableCollection<Foo> Foos { get; set; }
}
// This is actually what is bound to the top level ListBox
public ObservableCollection<FooRegion> FoosByRegion { get; set; }
public ObservableCollection<CategoryId> HiddenCategories { get; set; }
My XAML defines two ItemTemplates in the resources as follows,
<phone:PhoneApplicationPage.Resources>
...
<DataTemplate x:Key="MainItemTemplate">
<StackPanel >
<TextBlock Text="{Binding Name}"/>
<ListBox ItemsSource="{Binding Foos}"
ItemTemplate="{StaticResource SubItemTemplate}" />
</StackPanel>
</DataTemplate>
...
<DataTemplate x:Key="SubItemTemplate">
<StackPanel Opacity="{Binding IsHidden, Converter={StaticResource BoolToOpacity}}" >
<toolkit:ContextMenuService.ContextMenu>
<toolkit:ContextMenu>
<toolkit:MenuItem Header="{Binding IsHidden, ConverterParameter=unhide foo|hide foo,
Converter={StaticResource BoolToStrings}}" Tap="toggleHideFooContextMenuItem_Tap" />
</toolkit:ContextMenu>
</toolkit:ContextMenuService.ContextMenu>
<TextBlock Text="Some Text Here"/>
</StackPanel>
</DataTemplate>
...
</phone:PhoneApplicationPage.Resources>
These resources are called on to a 'nested' ListBox as follows,
<ListBox ItemTemplate="{StaticResource MainItemTemplate}" ItemsSource="{Binding FoosByRegion}" />
This method appears to only work piecemeal, Some Foo objects are updated in the UI, but others are not - as if the notification is not reaching the UI.
How should I be tackling this problem?
