ObservableCollection not noticing when Item in it changes (even with INotifyPropertyChanged)

Question

Does anyone know why this code doesn\'t work:

public class CollectionViewModel : ViewModelBase {  
    public ObservableCollection Con         


        

Answer 1

You can also use this extension method to easily register a handler for item property change in relevant collections. This method is automatically added to all the collections implementing INotifyCollectionChanged that hold items that implement INotifyPropertyChanged:

public static class ObservableCollectionEx
{
    public static void SetOnCollectionItemPropertyChanged(this T _this, PropertyChangedEventHandler handler)
        where T : INotifyCollectionChanged, ICollection 
    {
        _this.CollectionChanged += (sender,e)=> {
            if (e.NewItems != null)
            {
                foreach (Object item in e.NewItems)
                {
                    ((INotifyPropertyChanged)item).PropertyChanged += handler;
                }
            }
            if (e.OldItems != null)
            {
                foreach (Object item in e.OldItems)
                {
                    ((INotifyPropertyChanged)item).PropertyChanged -= handler;
                }
            }
        };
    }
}

How to use:

public class Test
{
    public static void MyExtensionTest()
    {
        ObservableCollection c = new ObservableCollection();
        c.SetOnCollectionItemPropertyChanged((item, e) =>
        {
             //whatever you want to do on item change
        });
    }
}