我的实体代表一对多:
@Entity
@Table(name = "Users")
public class User {
@Id
@GeneratedValue
private int id = -1;
@OneToMany(mappedBy = "user", cascade = CascadeType.ALL)
private List<SignIn> signIns;
}
@Entity
@Table(name = "SignIns")
public class SignIn {
@Id
@GeneratedValue
private int id;
@ManyToOne
private User user;
public SignIn(User user) {
this.user = user;
}
}
当我坚持一个用户,然后用创建的用户坚持一个登录时,一切正常(每个表将有 1 行)。当我重用创建的用户以保持另一个登录时,第一个登录行将被新登录所取代。
持续存在的代码:
User user = new User();
persist(user);
SignIn signIn = new SignIn(user);
SignIn signIn2 = new SignIn(user);
persist(signIn);
persist(signIn2);
private void persist(Object entity) {
EntityManager em = entityManagerFactory.createEntityManager();
EntityTransaction tx = em.getTransaction();
try {
tx.begin();
em.merge(entity);
tx.commit();
} finally {
if (tx.isActive()) {
tx.rollback();
}
em.close();
}
}
我忽略了什么?