public DataEntryViewModel()
{
DisplayName = "Enter Items";
var account = new Account();
Accounts = new ObservableCollection <IAccount>(Impromptu.AllActLike <IAccount>(account.All(), typeof(IAccount)));
var location = new Location();
Locations = new ObservableCollection <ILocation>(Impromptu.AllActLike <ILocation>(location.All(), typeof(ILocation)));
Purchases = new ObservableCollection <Purchase>();
Date = DateTime.Today;
}