带连接的spring data jpa本地查询

Question

如何在spring data jpa中执行本机查询，同时获取子实体？如果在子实体对象上有Eagy FetchType，则spring data将执行2个查询。1为父实体，1为子实体。

@Entity
public class Parent {
   @Id
   @GeneratedValue(strategy = GenerationType.IDENTITY)
   private long id;

   @Temporal(TemporalType.TIMESTAMP)
   private Date ts;

   @ManyToOne(fetch=FetchType.LAZY)
   private Child child;
}

@Entity
public class Child {
   @Id
   @GeneratedValue(strategy = GenerationType.IDENTITY)
   private long id;

   @OneToMany(fetch=FetchType.LAZY, mappedBy="parent")
   private Parent parent;
}

public interface ParentRepository extends Repository<Parent, Integer> {
    @Query(value = "SELECT * from parents p inner join children c on c.id=p.childId where TIMESTAMPDIFF(SECOND, p.ts, CURRENT_TIMESTAMP) < :interval", nativeQuery = true)
    Parent findOneByInterval(@Param("interval") long interval);
}

我还尝试向父类添加@NamedEntityGraph，并向查询方法添加@EntityGraph，但没有成功。

Answer 1

如果你想要父对象，你可以这样做

public interface ParentRepository extends Repository<Parent, Integer> {

    @Query(value = "SELECT p from parents p inner join children c on c.id=p.childId where TIMESTAMPDIFF(SECOND, p.ts, CURRENT_TIMESTAMP) < :interval", nativeQuery = true)
    Parent findOneByInterval(@Param("interval") long interval);
}

（或）Spring data jpa将为本机查询返回对象数组，

public interface ParentRepository extends Repository<Parent, Integer> {

    @Query(value = "SELECT * from parents p inner join children c on c.id=p.childId where TIMESTAMPDIFF(SECOND, p.ts, CURRENT_TIMESTAMP) < :interval", nativeQuery = true)
    List<Object[]> findOneByInterval(@Param("interval") long interval);
}