Question

public class Event {
    @OneToMany(cascade = CascadeType.ALL, orphanRemoval = true)
    private Set<User> users = new HashSet<>();
}

public class User {
    @OneToMany
    private Set<Event> events = new HashSet<>();
}

我如何建立从用户实体到事件的双向链接？

事件实体创建一个名为event_users的数据透视表。

Answer 1

您必须使用@ManyToMany映射：

public class Event {
    @ManyToMany(cascade = CascadeType.ALL, mappedBy="events")
    private Set<User> users = new HashSet<>();
}

public class User {
    @ManyToMany
    @JoinTable(
      name="event_users",
      joinColumns=@JoinColumn(name="user_ID", referencedColumnName="ID"),
      inverseJoinColumns=@JoinColumn(name="event_ID", referencedColumnName="ID"))
    private Set<Event> events = new HashSet<>();
}

我假设两个表的ID都称为ID，并且链接表包含user_id和event_id。

用户将是这里关系的拥有者。

两个实体上的JPA / Hibernate Bidirectional Set <object>

1 个答案: