XAML Combo Box is Empty on moving back to item in collection - xaml

Question

I have a Combo box and a Label :
<!-- Does not select appropriate value after moving back to current item in collection -->
<ComboBox
ItemsSource="{Binding Path=Items}"
SelectedValue="{Binding Path=SelectedItem, Mode=TwoWay}"
DisplayMemberPath="ItemName"
Margin="8,2,8,16" />
<!-- Displays correctly after moving back to current item in collection -->
<Label
Content="{Binding Path=SelectedItem.ItemName}"/>
I can set an Item in the combo box, but when I move from and back to the current item in the observable collection, the Combo Box does not set the SelectedValue as I expect (it remains empty) - the Label's content is set correctly - and its bound to the same thing.
What am I doing wrong?
Any help much appreciated.
Joe

Answer 1

Try using a ICollectionView as I described here (Answer).
The CollectionView takes care of your combobox and you can read and set the current item.
Just attach an event handler to the CurrentChanged Event from the ICollectionView.
XAML:
<ComboBox
ItemsSource="{Binding Path=Items}"
DisplayMemberPath="ItemName"
IsSynchronizedWithCurrentItem="True"
Margin="8,2,8,16" />
<Label Content="{Binding Path=CurrentItem.ItemName}"/>
ViewModel:
public class ViewModel :INotifyPropertyChanged
{
private ObservableCollection<Item> _items= new ObservableCollection<Item>();
private Item _currentItem;
public ObservableCollection<Item> Items
{
get { return _items; }
set { _items= value; OnPropertyChanged("Items");}
}
public Item CurrentItem
{
get { return _currentItem; }
set { _currentItem = value; OnPropertyChanged("CurrentItem");}
}
public ICollectionView ItemsView { get; private set; }
public ViewModel()
{
Items.Add(new Item{Id = Guid.NewGuid(), Name = "Item 1"});
Items.Add(new Item{Id = Guid.NewGuid(), Name = "Item 2"});
Items.Add(new Item{Id = Guid.NewGuid(), Name = "Item 3"});
ItemsView = CollectionViewSource.GetDefaultView(Items);
ItemsView .CurrentChanged += OnItemsChanged;
ItemsView .MoveCurrentToFirst();
}
private void OnItemsChanged(object sender, EventArgs e)
{
var selectedItem = ItemsView .CurrentItem as Item;
if (selectedItem == null) return;
CurrentItem= selectedItem ;
}
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged(string propertyName)
{
PropertyChangedEventHandler handler = PropertyChanged;
if (handler != null) handler(this, new PropertyChangedEventArgs(propertyName));
}
}
public class Item
{
public Guid Id { get; set; }
public string Name { get; set; }
}