Ich habe Probleme, eine Kaskade Persist-Operation für eine übergeordnete Entität durchzuführen. Wenn die untergeordnete Entität beibehalten wird, ist die Referenz (generierte ID) für die übergeordnete Entität null. Wie würde ich das richtig machen?So kaskadieren Sie persist mit JPA/EclipseLink
Instanzen:
@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;
...
}
Service:
@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);
}
}
MySQL Tabellen & Inserts:
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);