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상위 엔티티에서 계단식 지속 작업을 수행하는 데 문제가 있습니다. 하위 엔티티가 지속되면 상위 엔티티에 대한 참조 (생성 된 ID)는 null입니다. 어떻게 이것을 올바르게 유지할 수 있습니까?JPA/EclipseLink를 사용하여 계단식 유지하는 방법
엔티티 :
@Entity
public class Contact {
@Id @GeneratedValue(strategy=GenerationType.TABLE, generator="contact_gen")
@TableGenerator(name="contact_gen",
table="id_gen", pkColumnName="gen_name",
valueColumnName="gen_val", pkColumnValue="cont_gen")
@Column(name="contact_id")
private Long id;
@Column(name="name")
private String name;
@OneToMany(mappedBy="contact", cascade=CascadeType.PERSIST)
private List<Address> addresses = new ArrayList<Address>();
public void addAddress(Address address) {
addresses.add(address);
}
...
}
@Entity
public class Address {
@Id @GeneratedValue(strategy=GenerationType.TABLE, generator="address_gen")
@TableGenerator(name="address_gen",
table="id_gen", pkColumnName="gen_name",
valueColumnName="gen_val", pkColumnValue="addr_gen")
@Column(name="address_id")
private Long id;
@Column(name="full_address")
private String fullAddress;
@ManyToOne
@JoinColumn(name="contact_id")
private Contact contact;
...
}
서비스 :
@Stateless
public class ContactService {
@PersistenceContext
private EntityManager em;
public void createContact() {
Contact contact = new Contact();
contact.setName("Michael Scott");
contact.addAddress(new Address("1725 Slough Avenue");
em.persist(contact);
}
}
MySQL의 테이블 & 삽입 : 슬프게도
CREATE TABLE `contact` (
`contact_id` int(11) NOT NULL,
`name` varchar(45) NOT NULL
PRIMARY KEY (`contact_id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
CREATE TABLE `address` (
`address_id` int(11) NOT NULL,
`full_address` varchar(100) NOT NULL,
`contact_id` int(11) NOT NULL,
PRIMARY KEY (`address_id`),
KEY `FK_ADDRESS_contact_id` (`contact_id`),
CONSTRAINT `FK_ADDRESS_contact_id` FOREIGN KEY (`contact_id`) REFERENCES `contact` (`contact_id`) ON DELETE NO ACTION ON UPDATE NO ACTION
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
CREATE TABLE id_gen (
gen_name VARCHAR(80),
gen_val INT,
PRIMARY KEY (gen_name)
);
INSERT INTO id_gen (gen_name, gen_val) VALUES ('cont_gen', 0);
INSERT INTO id_gen (gen_name, gen_val) VALUES ('addr_gen', 0);