[英]Clear ManyToMany Relationship with JPA / JPQL
I have users and roles.我有用户和角色。 And each user can have many roles.
每个用户可以有很多角色。
I want to have a bulk operation like remove all User-Roles but keep Users and Roles.我想要进行批量操作,例如删除所有用户角色但保留用户和角色。 So how can i truncate the manyToMany Table only?
那么我怎样才能只截断 manyToMany 表呢?
The long way would be findAllUsers -> for each user.roles = new Hashset() -> saveAll(users)很长的路要走 findAllUsers -> for each user.roles = new Hashset() -> saveAll(users)
@Entity
@Table
public class Role {
@Id
@Column(name = "id", unique = true, nullable = false)
private Long id;
@ManyToMany(mappedBy = "roles")
private Set<User> users = new HashSet<>();
}
@Entity
@Table
public class User {
@Id
@Column(name = "id", unique = true, nullable = false)
private Long id;
@ManyToMany(cascade = {CascadeType.DETACH, CascadeType.MERGE, CascadeType.PERSIST})
@JoinTable(
name = "UserRole",
joinColumns = {@JoinColumn(name = "id")},
inverseJoinColumns = {@JoinColumn(name = "id")})
private Set<Role> roles = new HashSet<>();
}
@Repository
public interface UsersRepository extends JpaRepository<User, Long> {
@Modifying
@Query("UPDATE User u SET u.roles = null")
void clearAllRoleRelations();
}
I have tried this, but get an exception Not supported for DML operations [UPDATE users.entity.User u SET u.roles = null]我已经尝试过了,但是得到了一个异常不支持 DML 操作 [UPDATE users.entity.User u SET u.roles = null]
Ditch the @ManyToMany
and create an enitity for the join table. @ManyToMany
并为连接表创建一个实体。 This way you'll have full control over the deletion.这样您就可以完全控制删除。
I got it working, but with a native query which then requires an entityManager.clear if i want to use this within the same transaction.我让它工作了,但是使用本机查询,如果我想在同一个事务中使用它,则需要 entityManager.clear。
@Modifying
@Query(nativeQuery = true, value = "DELETE FROM user_role")
void clearAllRoleRelations();
@Autowired
private EntityManager entityManager;
@Test
public void clearAllRoleRelations() {
//given
Role roleIn = new Role();
roleIn.setId(27L);
User userIn = new User();
userIn.Id(12L);
//do
roleIn = rolesRepository.save(roleIn);
userIn = usersRepository.save(userIn);
userIn.getRoles().add(roleIn);
usersRepository.save(userIn);
//verify
usersRepository.clearAllRoleRelations();
//important within the same transaction (native query)
entityManager.clear();
Optional<User> userOut = usersRepository.findById(userIn.getId());
assertThat(userOut.isPresent()).isTrue();
assertThat(userOut.get()).isEqualTo(userIn);
assertThat(userOut.get().getRoles()).isEmpty();
}
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