spring data jpa 原生查询与 join fetch

Question

如何在 spring data jpa 中执行本机查询，同时获取子实体？如果我在子实体对象上有 Eager FetchType，则 spring 数据正在执行 2 个查询。 1 个用于父实体，1 个用于子实体。

有没有办法只执行 1 个本机查询来获取父实体和子实体？

家长：

@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;
}

孩子：

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

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

查询：

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);
}

我正在使用 Hibernate 5、MySQL 以及 Spring Data JPA。

我还尝试将 @NamedEntityGraph 添加到父类，将 @EntityGraph 添加到查询方法，但没有成功。

Answer 1

如果你想要Parent对象，你可以这样尝试

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 将返回本机查询的对象数组 所以，

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);
}

Answer 2

对我有用的解决方案如下

 @Query(value = "select distinct f.* " + 
        "from form as f " + 
        "inner join form_action as fa on f.id= fa.form_id " + 
        "where  rfa.rol_id = :rol_id", nativeQuery = true)
List<Form> findFormByRolIdParamsNative(@Param("rol_id") Long rol_id);