How to push data into the model?

Question

Java

There are 3 entities:
1, Zone
2. Description of the Zone
3. Language The
description of the Zone contains the id "Zone" and the id "Language".
I need to get the Zone Description object from the Zone,
when I got the Zone by id, I can transfer the Language id to it.
How do I map objects if the Zone doesn't know about Languages?

Answer 1

Mapping is easy

@Entity
public class Zone {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;

    @OneToOne(mappedBy = "zone")
    private ZoneDescription description;

    // Геттеры и сеттеры не указаны для краткости
}

@Entity
public class ZoneDescription {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;

    @OneToOne
    private Zone zone;

    @ManyToOne(optional = false)
    private ZoneLanguage language;

    // Геттеры и сеттеры не указаны для краткости
}

@Entity
public class ZoneLanguage {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;

/*  Раскоментировать, если нужна двунаправленная связь
    @OneToMany(mappedBy = "language")
    private Set<ZoneDescription> descriptions = new HashSet<>();
*/

    // Геттеры и сеттеры не указаны для краткости
}

And then just as easily in the application code

Zone zone = zoneRepository.getById(zoneId);
ZoneDescription description = zone.getDescription();