Question

我有两个实体类.User和FriendStatus.Friend状态保存有关来自其他用户的朋友请求的数据。

用户：

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

@OneToMany(cascade = CascadeType.ALL, mappedBy = "acceptor")
@LazyCollection(LazyCollectionOption.FALSE)
private List<Message> acceptedMessages;

@OneToMany(cascade = CascadeType.ALL, mappedBy = "sender")
@LazyCollection(LazyCollectionOption.FALSE)
private List<Message> sentMessages;

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
private String username;
private String password;

@Column(name = "phone_number")
private String phoneNumber;

@OneToMany(cascade = CascadeType.ALL)
@LazyCollection(LazyCollectionOption.FALSE)
private List<User> friends;

@OneToMany(cascade = CascadeType.ALL,mappedBy="requestAcceptor")
@LazyCollection(LazyCollectionOption.FALSE)
@JsonIgnoreProperties("requestAcceptor")
private List<FriendStatus> acceptedFriendRequests;

@OneToMany(cascade = CascadeType.ALL,mappedBy = "requestSender")
@LazyCollection(LazyCollectionOption.FALSE)
@JsonIgnoreProperties("requestSender")
private List<FriendStatus> sentFriendRequests;

@Column(name = "profile_status")
private String profileStatus;

@Enumerated(EnumType.STRING)
@Column(name = "activation_status")
private UserActivationStatus activationStatus;

FriendStatus：

@Entity
@Table(name="FRIEND_STATUS")
public class FriendStatus implements Serializable {

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private long Id;

@ManyToOne(cascade = CascadeType.ALL)
@JoinColumn(name="request_sender_id")
@JsonIgnoreProperties("sentFriendRequests")
private User requestSender;

@ManyToOne(cascade = CascadeType.ALL)
@JoinColumn(name="request_acceptor_id")
@JsonIgnoreProperties("acceptedFriendRequests")
private User requestAcceptor;

@Enumerated(EnumType.STRING)
@Column(name = "request_status")
private FriendRequestStatus friendRequestStatus;

当我第一次将FriendStatus对象保存到数据库时，它工作正常。但是当我使用相同的requestAcceptor对象第二次保存对象时，hibernate从request_acceptor_id列中删除先前的id并将其写入新行.HELP ME PLEASE。< / p>

编辑：

这是我将对象保存到db的方法。

public T create(T object) {
T  objectFromDB = object;
Session session = NewHibernateUtil.getSessionFactory().openSession();
Transaction transaction = null;
try {
    transaction = (Transaction) session.beginTransaction();
    session.save(object);        
    transaction.commit();

} catch (HibernateException e) {
        if (session != null){
                session.getTransaction().rollback();
            }
    e.printStackTrace();
} finally {
    session.close();
}
return objectFromDB;
}

这是我调用create method的方法：

public void sendFriendRequest(FriendStatus object) {
    FriendStatus status = fDao.create(object);//fDao is the object from Dao class which includes create method.
}

这是我的控制者：

@RequestMapping(value="/sendFriendRequest",method = RequestMethod.POST,consumes = MediaType.APPLICATION_JSON,produces = MediaType.APPLICATION_JSON)
public String sendFriendRequest(@RequestBody FriendStatus status) {
    serviceUser.sendFriendRequest(status);//serviceUser is the object from class that includes sendFriendRequest method.
    return "OK";
}

这是我在db中的表：

+====+================+=====================+===================+
| id | request_status | request_acceptor_id | request_sender_id |
+====+================+=====================+===================+
| 18 | WAITING        | NULL                |                29 |
+----+----------------+---------------------+-------------------+
| 19 | WAITING        | 23                  |                30 |
+----+----------------+---------------------+-------------------+

当我使用id为29的requestSender保存FriendStatus对象（来自客户端）时，id为23的requestAcceptor对象hibernate将其保存到id为18的列。之后我用requestSender保存第二个FriendStatus对象的id是30和requestAcceptor对象，其id是23，hibernate用id为18的行替换request_acceptor_id，然后在db中创建新行，request_acceptor_id是23.但我想要当我添加第二个对象时，第一个对象不更改。当我使用相同的request_acceptor_id创建新列时，我不想将request_acceptor_id替换为NULL。

Answer 1

与你的级联设置有关，

尝试使用以下内容保存：

public void sendFriendRequest(FriendStatus status) {

    User requester=userDao.findOne(status.getRequestAcceptor.getId());
    User sender=userDao.findOne(status.getRequestSender.getId());
    ......
    statusDao.create(status);
    status.getRequestAcceptor(requester);
    status.getRequestSender(sender);
    statusDao.update(status);

}

状态携带的用户具有私有List sentFriendRequests和私有List acceptedFriendRequests;设置为空列表

如果您的交易超出整个功能，它会更好，那么您可以使用： sender.getSentFriendRequests（）。add（status）和reqester.getacceptedFriendRequests（）。add（status）;我想这是@OneToMany，Cascade.All

的重点

否则你可以从集合中删除级联规则

hibernate @onetomany bidirectinal mapping无法正确映射数据

1 个答案: