public void LoadData() { GetRoomTypes = new ObservableCollection <RoomType>(); using (RetailContext context = new RetailContext()) { var rmtypes = context.RoomTypes.ToList(); foreach (RoomType rt in rmtypes) { GetRoomTypes.Add(rt); } } if (RoomTypes != null) { RoomTypes.Clear(); } else { RoomTypes = new ObservableCollection <RoomType>(); } foreach (RoomType rs in GetRoomTypes) { RoomTypes.Add(rs); } }