JPA没有将外键保存到@OneToMany关系

Question

我正在使用Spring和Hibernate作为JPA提供程序,并且正在尝试获取@OneToMany(具有许多phonenumbers的联系人)以将外键保存在电话号码表中.从我的表单中我得到一个Contact对象,其中包含Phone(数字)列表.Contact正确持久化(Hibernate从指定的序列中获取PK).电话(号码)列表也会以正确的PK保留,但是联系人表格中没有FK.

public class Contact implements Serializable {

    @OneToMany(mappedBy = "contactId", cascade = CascadeType.ALL, fetch=FetchType.EAGER)
    private List<Phone> phoneList;

}

public class Phone implements Serializable {

    @JoinColumn(name = "contact_id", referencedColumnName = "contact_id")
    @ManyToOne
    private Contact contactId;

}

@Repository("contactDao")
@Transactional(readOnly = true)
public class ContactDaoImpl implements ContactDao {

    @Transactional(readOnly = false, propagation = Propagation.REQUIRES_NEW)
    public void save(Contact c) {
        em.persist(c);
        em.flush();
    }
}


@Controller
public class ContactController {
    @RequestMapping(value = "/contact/new", method = RequestMethod.POST)
    public ModelAndView newContact(Contact c) {
        ModelAndView mv = new ModelAndView("contactForm");
        contactDao.save(c);
        mv.addObject("contact", c);
        return mv;
    }
}

希望我得到上面的所有相关内容,否则请告诉我.

Answer 1

您必须自己管理Java关系.对于这种事情,你需要这样的东西:

@Entity
public class Contact {
  @Id
  private Long id;

  @OneToMany(cascade = CascadeType.PERSIST, mappedBy = "contact")
  private List<Phone> phoneNumbers;

  public void addPhone(PhoneNumber phone) {
     if (phone != null) {
        if (phoneNumbers == null) {
            phoneNumbers = new ArrayList<Phone>();          
        }
        phoneNumbers.add(phone);
        phone.setContact(this);
     }
  }

  ...
}

@Entity
public class Phone {
  @Id
  private Long id;

  @ManyToOne
  private Contact contact;

  ...
}

Answer 2

回答Cletus的回答.我会说,@column在id字段以及所有序列内容上都有注释很重要.使用@OneToMany注释的mappedBy参数的替代方法是使用@JoinColumn注释.

有点像你需要看一下addPhone的实现.应该是这样的.

public void addPhone(PhoneNumber phone) {
    if (phone == null) {
        return;
    } else {
        if (phoneNumbers == null) {
            phoneNumbers = new ArrayList<Phone>();
        }
        phoneNumbers.add(phone);
        phone.setContact(this);
    }
}

Answer 3

如果 Contact-Phone 关系是单向的，您也可以mappedBy在@OneToMany注释中替换 为@JoinColumn(name = "contact_id")。

@Entity
public class Contact {
  @Id
  private Long id;

  @OneToMany(cascade = CascadeType.PERSIST)
  @JoinColumn(name = "contact_id")
  private List<Phone> phoneNumbers;

  // normal getter/setter
  ...
}

@Entity
public class PhoneNumber {
  @Id
  private Long id;

  ...
}

类似于JPA @OneToMany -> Parent - Child Reference (Foreign Key)