java - 如何定义单向OneToMany JPA关系而不需要任何级联？

Question

当我试图拯救人时，它并没有拯救任何东西，无论是人还是城市。我不想保存或更新 City 对象。我只想更新/删除 joinColumn。有什么办法可以做到这一点吗？

Person person = new Person();
person.setCities(...);
personDAO.save(person);



public class Person{

    @OneToMany(fetch = FetchType.EAGER)
    @JoinColumn(name = "city_id")
    private List<City> cities;

}


public class City{
    @Id
    @Column(name = "city_id")
    @GeneratedValue(generator = "system-uuid")
    @GenericGenerator(name = "system-uuid", strategy = "org.hibernate.id.UUIDGenerator")
    private String cityId;

}

Answer 1

首先在 City 端定义 @ManyToOne 映射:

@ManyToOne
@JoinColumn(name = "person_id")
private Person person;

然后添加mappedBy属性并删除@JoinColumn:

@OneToMany(fetch = FetchType.EAGER, mappedBy = "person")
private List<City> cities;

当您保存/更新时，您必须设置依赖项两侧的实体:

Person person = new Person();
person.setCities(...);

for(City city: cities){
   city.setPerson(person);
}  

personDAO.save(person);

删除也是如此。您必须删除两侧的实体引用。