public TravelReservation(Travel travel)
 {
     IsModify = true;
     Travel = travel;
     Reservation = new ReservationHelper();
     Reservation.ID_Travel = Travel.ID;
 }
 public TravelReservation(Reservation reservation)
 {
     IsModify = false;
     Reservation = new ReservationHelper(reservation);
     Travel = getTravel(Reservation.ID_Travel);
 }