WPF How to cast ListBox.ItemsSource into ObservableCollection

Question

I have written a Behavior which allows to reorder a ListBox. To work properly the ListBox's ItemsSource has to be an ObservableCollection<...>, so I can call the Move(from,to)-method.

My problem is: How can I cast the ListBox.ItemsSource into a ObservableCollection.

I already tried:

ObservableCollection<object> test = listBox.ItemsSource as ObservableCollection<object>;

which does not work, because ObservableCollection doesn't support covariance.

Is your question because you know `listBox.ItemsSource` is *some* type of `IList`, but you just don't know what at runtime? — user7116, Apr 27 '12 at 08:43
EDIT: I need the list to be an ObservableCollection instead of IList — JensPfister1, Apr 27 '12 at 08:52

score 3 · Accepted Answer · answered Apr 27 '12 at 08:56

3

Since you know the method you'd like to call, ObservableCollection<T>.Move, you can use simple reflection:

var move = listBox.ItemsSource
                  .GetType()
                  .GetMethod("Move");
if (move != null)
{
    move.Invoke(listBox.ItemsSource, new[] { old, new });
}
else
{
    // IList fallback?
}

answered Apr 27 '12 at 08:56

user7116

63,008
17
141
172

I'm using the IList-Approach by default, but your answer is a (dirty) nice approach, too! – JensPfister1 Apr 27 '12 at 09:20

WPF How to cast ListBox.ItemsSource into ObservableCollection

1 Answers1

Linked