Jpa many-to-many, how can I insert data into only 2 tables

I have some problem.

I have 3 tables:

users (id, name, ..)
roles (id, name)
user-role (user_id, role_id)

      

        
        
        
      

    

When I do a many-to-many relationship and save () I have 3 inserts.

User:

@Entity
@Table(name = "user")
public class User implements Serializable {

    public static final String UK_EMAIL = "uk_email";

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id")
    private Long id;

    @ManyToMany(fetch = FetchType.LAZY, cascade = {CascadeType.PERSIST, CascadeType.MERGE})
    @JoinTable(
        name = "system_user_role",
        joinColumns = {@JoinColumn(name = "user_id", referencedColumnName = "id")},
        inverseJoinColumns = {@JoinColumn(name = "role_id", referencedColumnName = id")}
    )
    private List<SystemRole> userRole;

    public List<SystemRole> getUserRole() {
        return userRole;
    }

      

        
        
        
      

    

SystemRole;

@Entity
@Table(name = "system_role")
public class SystemRole implements Serializable {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id")
    private Long id;

    @Column
    private String name;

    @ManyToMany(fetch = FetchType.LAZY)
    @JoinTable(
        name = "system_user_role",
        joinColumns = {@JoinColumn(name = "role_id", referencedColumnName = "id")},
        inverseJoinColumns = {@JoinColumn(name = "user_id", referencedColumnName = "id")}
    )
    private List<User> users;

    public List<User> getUsers() {
        return users;
    }

    public void setUsers(List<User> users) {
        this.users = users;
    }

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}

      

        
        
        
      

    

PLEASE tell me if I can only insert data into 2 tables, only (User and user_role? I have a list of roles and I shouldn't add a new role when creating a new user.

So when I do this:

SystemRole role1 = systemRoleService.findOne("ROLE_ADMIN");
userForm.setUserRole(Lists.newArrayList(role1));
....
final User saved = userRepository.save(user);
....

      

        
        
        
      

    

I am getting the error:

org.springframework.dao.InvalidDataAccessApiUsageException: detached entity passed to  persist:...

      

        
        
        
      

    

If I do:

@Service("userService")
@Transactional
public class UserServiceImpl implements UserDetailsService, ResourceService<User> {
private final static Logger LOGGER = LoggerFactory.getLogger(UserServiceImpl.class);

@Autowired
private UserDAO userRepository;
@Autowired
private SystemRoleDAO systemRoleRepository;

@Override
@Transactional(rollbackFor = ResourceException.class)
public User create(User user) throws ResourceException {
    try {
        SystemRole role1 = systemRoleRepository.findOne(6l);
        user.setUserRole(Lists.newArrayList(role1));

        user.setId(62l); // !!! if set user ID - it works CORRECT

        final User saved = userRepository.save(user);
        return saved;
    } catch (DataIntegrityViolationException ex) {
...

      

        
        
        
      

    

UserDAO:

@Repository
public interface UserDAO extends JpaRepository<User, Long> {
...

      

        
        
        
      

    

SystemRoleDAO:

@Repository
public interface SystemRoleDAO extends JpaRepository<SystemRole, Long> {

      

        
        
        
      

    

It works, but I have 3 inserts.

When I create a new user, I need to select a role from the list, add it to the user, and save the new user.

Many thanks.