public IEnumerable <Passenger> ChangeSeats(SeatDTO seatDTO) // Use seatNumber or passenger name? { Passenger passenger1 = _passengerRepository.GetPassengerBySeatNumber(seatDTO.SeatNumber1); Passenger passenger2 = _passengerRepository.GetPassengerBySeatNumber(seatDTO.SeatNumber2); passenger1.SeatNumber = seatDTO.SeatNumber2; passenger2.SeatNumber = seatDTO.SeatNumber1; _passengerRepository.SaveChanges(); List <Passenger> passengers = new List <Passenger>() { passenger1, passenger2 }; return(passengers); }