I'm having trouble making OrderEntity
object load BillingAddress
lazily. I've seen questions revolving around this asked a lot and followed instructions, including adding optional = false but BillingAddress
still gets loaded whenever I findById
an OrderEntity
.
These are my entities (reduced for the sake of this question):
OrderEntity
@Entity
@Table(name = "orders", schema = "glamitoms")
public class OrderEntity {
@Id
@Column(name = "id")
private int id;
@OneToOne(mappedBy = "order", cascade = CascadeType.ALL, fetch = FetchType.LAZY, optional = false)
private BillingAddressEntity billingAddress;
}
BillingAddressEntity
@Entity
@Table(name = "billing_address", schema = "glamitoms")
public class BillingAddressEntity {
@Id
@Column(name = "order_id")
private int id;
@OneToOne(fetch = FetchType.LAZY)
@MapsId
private OrderEntity order;
}
TestController
@RestController
public class TestController {
private OrdersDAO ordersDAO;
@Autowired
public TestController(OrdersDAO ordersDAO) {
this.ordersDAO = ordersDAO;
}
@GetMapping("/test")
public void test() {
OrderEntity orderEntity = ordersDAO.findById(1).get();
}
}
OrdersDAO
@Repository
public interface OrdersDAO extends JpaRepository<OrderEntity, Integer> {
}
The table billing_address
has a FK referencing orders. I've read contradicting answers saying adding optional = false
should load entities lazily, but for me, that doesn't seem to work. Am I missing something in any of these entities?
Have a look at Vlad Mihalceas article The best way to map a @OneToOne relationship with JPA and Hibernate
As described there, one of the solutions would be to drop the relation on the parentside...
@Transient
private BillingAddressEntity billingAddress;
and load the BillingAddressEntity
manually using the shared id.
if (order.billingAddress == null)
{
order.billingAddress = entityManager.find(BillingAddressEntity.class, order.id);
}
Another approach would be to drop the shared key, use a foreign key field instead and mark the relation as @ManyToOne
. This will sacrifice the OneToOne constraint check though.
@ManyToOne(cascade = CascadeType.ALL, fetch = FetchType.LAZY)
@JoinColumn(name = "billing_address_id")
private BillingAddressEntity billingAddress;
Then there's also the byte code enhancement which would allow you to make this a @LazyToOne(LazyToOneOption.NO_PROXY)
relation. I can't help you with that though, as I've never done that myself.
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