@ManyToOne association fetching eagerly despite being marked Lazy

Hibernate ORM
1

Edit: Hibernate version 6.6.0.Final

I have a Store and a Region. A Region can have many stores and a Store can belong to one Region. My problem is that whenever I select a Store that has a region. A select statement fetching that Region is automatically created.

Here is my Store class:

@Entity
@Table(name="store")
public class Store {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "store_id", nullable = false)
    private Long storeId;

    @NaturalId
    @Column(name = "store_code", length = 10, unique = true ,nullable = false)
    private String storeCode;

    @ManyToOne(fetch = FetchType.LAZY, optional = false)
    @JoinColumn(name= "region_code", referencedColumnName = "region_code", foreignKey = 
    @ForeignKey(name="store_region"))
    private Region region;

    @Column(name = "region_code", updatable = false, insertable = false)
    private String regionCode;
    
    @Column(name = "name", nullable = false)
    private String name;

    @Column(name = "address")
    private String address;

    @Column(name= "city")
    private String city;

    @Column(name= "state", nullable = false)
    private String state;

    //Getters and Setters omitted....

}

Here is my Region class

@Entity
@Table(name="region")
public class Region {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "region_id", nullable = false)
    private Long regionId;


    @OneToMany(mappedBy = Store_.REGION, fetch = FetchType.LAZY)
    private Set<Store> stores;

    @Column(name = "region_code", length = 10, unique = true ,nullable = false)
    private String regionCode;

    @Column(name = "region_name", unique = true ,nullable = false)
    private String regionName;

    //Getters and Setters omitted....

}

Here is a test case

class JPAUnitTestCase {

    private EntityManagerFactory entityManagerFactory;

    @BeforeEach
    void init() {
        entityManagerFactory = Persistence.createEntityManagerFactory( "templatePU" );
        SessionFactory sessionFactory = entityManagerFactory.unwrap(SessionFactory.class);
        Region region = new Region("WEST", "WE");
        Store store1 = new Store("1", "Billy's Hardware", "CA");
        Store store2 = new Store("2", "Sandy's Restaurant", "CA");

        Store store3 = new Store("3", "Dick's Hardware", "OH");

        Session session = sessionFactory.openSession();
        Transaction t = session.beginTransaction();
        region = session.merge(region);
        store1.setRegion(region);
        store2.setRegion(region);

        session.persist(store1);
        session.persist(store2);
        session.persist(store3);
        t.commit();
        session.close();
    }

    @AfterEach
    void destroy() {
        entityManagerFactory.close();
    }

    // Entities are auto-discovered, so just add them anywhere on class-path
    // Add your tests, using standard JUnit.
    @Test
    void hhh123Test() throws Exception {
        EntityManager entityManager = entityManagerFactory.createEntityManager();
        SessionFactory sessionFactory = entityManagerFactory.unwrap(SessionFactory.class);
        Session session = sessionFactory.openSession();
        List<Store> stores = session.createSelectionQuery("select store from Store store", Store.class).getResultList();
        session.close();;
    }
}

If you view the logs from the hhh123Test(), you can see two select statements for each of the regions being created. Any advice? I’m unsure of how to proceed from here

2

The reason for this is that Hibernate ORM can not create a proxy based on a foreign key column that refers to a non-primary key. Proxying only works based on primary key.
You can use bytecode enhancement though to defer the loading to the first access of the association.