Hibernate 用户消息关系

Question

如何在 Hibernate 实体中创建下一种关系类？用户通过创建消息（发送者、接收者、消息）向另一个用户发送消息。数据库看起来像这样：

+-----------------------------------+
|                user               |
+-----------------------------------+
| id |   nickname  |    password    |
+----+-------------+----------------+
|  1 |    admin    |      pass      |
+----+-------------+----------------+

+------------------------------------------------+
|                     message                    |
+-----------------------------------|------------+
| id |  sender_id  |  receiver_id   |  message_t |
+----+-------------+----------------+------------+
|  1 |      10     |       12       |      hi    |
+----+-------------+----------------+------------+

实体类必须是什么样子？

@Entity 
@Table(name="profiles")
public class Message {

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

    @ManyToOne
    @JoinColumn(name = "sender")
    private User sender;

    @ManyToOne
    @JoinColumn(name = "receiver")
    private User receiver;

    @Column(name = "message")
    String message;
}

@Entity
@Table(name = "users")
public class User {

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

    @OneToMany(mappedBy = )
    List<Message> messages;
}

映射...什么？我需要找到所有消息，其中当前用户作为发送者 OR/AND 接收者存在。（"AND" 因为用户可以向自己发送消息）。

Answer 1

如果您需要查找用户发送或接收的消息，您已经拥有消息实体中的所有信息，用户映射对您来说并不重要。

select m from Message m where m.sender!=m.receiver and (m.sender=:user or m.receiver=:user).

关系有两种类型：单向和双向。

如果在用户的实体映射中你应该保留关于发送者和接收者的信息（你已经在消息中有这个信息）那么双向关系：

@Entity
@Table(name = "users")
public class User {

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

    @OneToMany(mappedBy = receiver)
    private List<Message> messagesRecived;

    @OneToMany(mappedBy = sender)
    private List<Message> messagesSended;
}

Hibernate 用户消息关系

Hibernate user messages relation

java

hibernate

one-to-many

hibernate-onetomany

mappedby