void btnSaveBookingEquipment_Click(object sender, RoutedEventArgs e) { List <BookingRoomEquipment> saveList = (List <BookingRoomEquipment>)gvwBookingEquipment.ItemsSource; //Get delete items : foreach (BookingRoomEquipment oldItem in _currentBookingEquipments) { bool isDeleted = true; foreach (BookingRoomEquipment saveItem in saveList) { if (saveItem.BookingRoomEquipmentId == oldItem.BookingRoomEquipmentId) { isDeleted = false; break; } } if (isDeleted) { oldItem.IsDeleted = true; saveList.Add(oldItem); } } Globals.IsBusy = true; DataServiceHelper.SaveBookingRoomEquipmentAsync(saveList, SaveBookingEquipmentCompleted); }