Question

我有一个简单的父子关系。

问题：在我的数据库中，有时会有多个子元素映射到同一个父元素。

@Entity
public class PersonEntity {
    @Id
    private long id;

    //assume every person can only have one car
    @OneToOne(mappedBy = "person", cascade = CascadeType.ALL, orphanRemoval = true)
    private CarEntity car;

    private String name;
}

@Entity
public class CarEntity {
    @Id
    private long id;

    @OneToOne
    @JoinColumn(name = "fk_person_id", foreignkey = @ForeignKey("name = "fk_person"))
    private PersonEntity person;

    private String name;
}

问题：如果有多个car元素映射到相同的人员实体，我怎么会发生？ hibernate如何能够持久保存这些元素？他们在哪里可以来自？

因此，当我获取具有多个汽车映射的人员实体时，我当然是个例外：

Caused by: org.hibernate.HibernateException: More than one row with the given identifier was found: 123, for class: CarEntity...

旁注：我最终想要删除重复的CarEntity并且只保留最新的@Transactional public PersonEntity createUpdatePerson(PersonDTO dto) { PersonEntity entity = dao.findByPersonName(dto.getName); //CrudRepository by spring if (entity == null) { entity = new Person(); } mergeDTO(dto, entity); //copy and fill new values if (person.getId() == null) dao.save(entity); return entity; } private void mergeDTO(PersonDTO dto, PersonEntity entity) { if (dto.getCar() != null) { if (entity.getCar() == null) entity.setCar(new Car()); entity.getCar().setName(dto.getCar().getName()); entity.getCar().setPerson(entity); } }。但是我怎么能阻止将来发生这种情况呢？

更新

var foo = ...// some function assignment
var fooString = foo.toString()
...
// add some alert to foo
...
var fooWithAlert = new Function(forStringWithAlert)

@OneToOne实体的重复条目？

0 个答案: