Question

I’m noticing that when using EF CodeFirst, and binding my UI to an ObservableCollection<T> via the DBSet.Local property recommended here, that the UI will update when entities are added to the DBContext but not when they are modified.

It would seem that the DBSet.Local collection is not being notified that my entities have changed. When using EF Code-First do I need to implement INotifyPropertyChanged for all of my fields? I have not seen this in any of the examples on Code-First and it seems to go against the purpose, but perhaps I’m mistaken.

I can post some example code if you feel that the ObservableCollection should be receiving change notifications and that something must be wrong in my Entity classes or something.

Edit So, just to be sure, if I have code like the following in my ViewModel

private ClientContext clientContext;
private Client client;
public Client Client
{
    get { return client; }
    set { 
          client = value; 
          NotifyOfPropertyChange(() => Client);
          NotifyOfPropertyChange(() => Clients);
        }
}
public ObservableCollection<Client> Clients { get { return clientContext.Clients.Local; }}

Let’s also assume my View has a Listbox with Itemssource set to Clients, and SelectedItem set to Client. I still need to implement INotifyPropertyChanged in my Model, even though I’m using it in my ViewModel?

Answer 1

Yes,

Every element that you want to update the UI when a property of it is modified must implement INotifyPropertyChange.

The reason for this is, the UI knows when the collection changes, but if the property of one of those elements changes, there is no CollectionChanged event associated with it, so the UI is ignorant

See also: Entity Framework CTP5 Code First, WPF – MVVM modeling