How to pull related entity in Hibernate?

Question

Hibernate

Hello, I want to understand how to work with related entities in Hibernate
Here is an example we have two entities :

@Entity
@Table(name = "usr")
public class User {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @Column(nullable = false)
    private String username;

    @Column(nullable = false)
    private String password;

    @Column(nullable = false)
    private String email;

    private boolean active;

    @Enumerated(EnumType.STRING)
    private Role role;

    @OneToMany(fetch = FetchType.LAZY, mappedBy = "responsibleUser", cascade = CascadeType.ALL)
    private List<GrowBox> growBoxes;
//def-constructor , getters, setters
}

and

@Entity
@Table(name = "growBoxes")
public class GrowBox {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    Long id;

    @Column(nullable = false)
    private Integer length;

    @Column(nullable = false)
    private Integer width;

    @Column(nullable = false)
    private Integer height;

    @OneToMany(fetch = FetchType.LAZY, mappedBy = "responsibleGrowBox", cascade = CascadeType.ALL)
    private List<Plant> plants;

    @OneToMany(fetch = FetchType.LAZY, mappedBy = "activeGrowBox", cascade = CascadeType.ALL)
    private List<Sensor> sensors;

    @ManyToOne
    @JoinColumn(name = "user_id")
    private User responsibleUser;
//def-constructor , getters, setters
}

I left the mapping to the will of the annotations (it seems like this is possible, correct, please, if not) by writing only

<mapping class="com.example.auth.entity.user.User"/>
        <mapping class="com.example.auth.entity.GrowBox"/>

and let's say the task is to find a box by user id and I wanted to do it in this way:

@Autowired
    SessionFactory sessionFactory;

   @Override
    public List<GrowBox> findByUser(Long userId) {

        Session session = sessionFactory.openSession();
        String hqlQuery = "from GrowBox where user_id =: userId";
        Query query = session.createQuery(hqlQuery);
        List growBoxes = query.getResultList();
        session.flush();
        session.close();
        return growBoxes;
    }

but then I remembered that in hql we work not with the base, but with the representation of the object => I can’t have any user_id, but what do I have in the object itself? and I have a private User responsibleUser field in it;
and the question arises: what should I pass to the Query parameter of the whole user in order to find boxes by his id (as for me it looks like something superfluous)
here, could you please describe how it should look right and why, thanks in advance

Answer 1

Asked the same question on a bourgeois stackofferflow
https://stackoverflow.com/questions/56886968/how-s...
String hqlQuery = "from GrowBox gb where gb.responsibleUser.id =: userId";