So, I have 2 entities:
Room:

@Entity
@Table(name = "rooms")
public class Room
{
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;
    private String type;
    private String image;
    private double price;
    @Column(columnDefinition = "TEXT")
    private String description;

    @ManyToOne(cascade = CascadeType.ALL)
    @JoinColumn(name = "guest_id", referencedColumnName = "id")
    private Guest guest_id;

    @ManyToOne(cascade = CascadeType.ALL)
    @JoinColumn(name = "guest_name", referencedColumnName = "name")
    private Guest guest_name;

Guest:

@Entity
@Table(name = "guests")
public class Guest
{
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;
    private String name;
    private String phone_num;
    private String email;
    private LocalDate check_in_date;
    private LocalDate check_out_date;

    @OneToOne
    @JoinColumn(name = "room_id", referencedColumnName = "id")
    private Room room_id;

As you can see in Room there are 2 foreign keys which reference id and name fields in Guest and 1 foreign key in Guest which references id field in Room.

In my controller there’s a method which is supposed update an entry inside my guests table:

@PostMapping("/update/{id}")
    public String updateGuest(@PathVariable Long id, @ModelAttribute("guest") Guest guest)
    {
        Guest existingGuest = guestRepository.findById(id).get();
        existingGuest.setName(guest.getName());
        existingGuest.setPhone_num(guest.getPhone_num());
        existingGuest.setEmail(guest.getEmail());
        existingGuest.setCheck_in_date(guest.getCheck_in_date());
        existingGuest.setCheck_out_date(guest.getCheck_out_date());
   
        guestRepository.save(guest);

        return "redirect:/guests/";
    }

It worked before I had foreign keys, but since there’s now a connection between fields I think I am supposed to also update fields inside rooms table. But I am honestly quite unsure how to do it.

I think I am supposed to create a method inside repository sort of like this:

@Repository
public interface RoomRepository extends JpaRepository<Room, Long>
{
    @Query("Select g From rooms g Where g.guest_id = :guestId")
    List<Room> findGuestById(@Param("guestId") String guestId);
}

Is my thinking here correct?

Massive thanks in advance!!