public SelectList GetAvailableSeats(int FlightID)
        {
            Flight flight = db.Flights.First(f => f.FlightID == FlightID);

            //List<Seats> AvailableSeats = new List<Seats>();

            List <Seats> AllSeats = Seats.GetValues(typeof(Seats)).Cast <Seats>().ToList();

            List <Seats> TakenSeats = new List <Seats>();

            foreach (ReservationFlightDetail ticket in flight.ReservationFlightDetails)
            {
                TakenSeats.Add(ticket.SeatAssignment);
            }

            List <Seats> AvailableSeats = AllSeats.Except(TakenSeats).ToList();

            SelectList allCitieslist = new SelectList(AvailableSeats);// "value", "text"

            return(allCitieslist);
        }