Question

如何从Entity对象获得父SubEntity对象。

subEntityRepository.findById(id)，然后getEntity()返回null实体对象。

@Entity
public class Entity {
    @Id
    private Long id;
    @Reference
    private List<SubEntity> subEntity;


    public Building(List<SubEntity> subEntity) {
        this.subEntity = subEntity;
    }

    //getters and setters
}

@Entity
public class SubEntity {
    @Id
    private Long id;

    @Reference
    private Entity entity;

    //getters and setters
}

public interface EntityRepository extends DatastoreRepository<Entity, Long> {}


public interface SubEntityRepository extends DatastoreRepository<SubEntity, Long>{}

P.S。这是Google DataStore数据库！没有OneToMany，没有其他JPA注释可用。

Answer 1

@Entity
@Table(name="entity")
public class Entity {

    @Id
    private Long id;

    @OneToMany(mappedBy="entity")
    private List<SubEntity> subEntity;

    ....
}

@Entity
@Table(name="subEntity")
public class SubEntity {
    @Id
    private Long id;

    @ManyToOne
    @JoinColumn(name = "entity")
    private Entity entity;

    //getters and setters
}

从Spring数据存储库获取父实体

1 个答案: