Two-way databinding, Silverlight and custom control / dependancy property

Question

If I create an dependency property on a custom control that takes an IEnumerable<T> .

For example with an IEnumerable<string> :

public static readonly DependencyProperty MyCollectionProperty =
    DependencyProperty.Register("MyCollection", typeof(IEnumerable<string>), typeof(MyControl), new PropertyMetadata(new List<string>()));

public IEnumerable<string> MyCollection
{
     get { return (IEnumerable<string>)GetValue(MyCollectionProperty); }
     set { SetValue(MyCollectionProperty, value); }
}

If I databind an ObservableCollection<T> or <string> in this case to it. Does Silverlight take care of the two-way databinding for me?

Answer 1

From MSDN "In particular, if you are using OneWay or TwoWay (for example, you want your UI to update when the source properties change dynamically), you must implement a suitable property changed notification mechanism such as the INotifyPropertyChanged interface"

ObservableCollection<T> implements INotifyPropertyChanged for you. IEnumerable<T> does not. If you want easy two way binding simply bind to an ObservableCollection<T> , and change your UpdateSourceTrigger to PropertyChanged . XAML:

<ItemSource = "{Binding Path=MyCollection, UpdateSourceTrigger=PropertyChanged}">