private async void CreateOnClick(object sender, RoutedEventArgs e) { Errors = new List <string>(); var cust = new Customer() { FirstName = Input.FirstName, LastName = Input.LastName, Email = Input.Email, Phone = Input.Phone }; var room = await businessLogic.GetRoomByNumber(Input.RoomNumber); if (room == null) { Errors.Add("Podano zły numer pokoju."); ErrorTable.ItemsSource = Errors; return; } var res = new Reservation() { FromDate = DateTime.Parse(Input.FromDate), ToDate = DateTime.Parse(Input.ToDate), NumberOfGuests = Input.NumberOfGuests, Customer = cust, Room = room }; var result = isNewRecord ? await businessLogic.AddReservation(res) : await businessLogic.UpdateReservation(res); if (result.Succeeded) { this.Close(); return; } foreach (var err in result.ErrorMessages) { Errors.Add(err); } ErrorTable.ItemsSource = Errors; return; }