如何在不查询实体的情况下对 jpa 的 @ManyToOne JoinColumn 执行“in”查询

Question

I have an entity like:

@Entity
class Blog{
    @Id
    private Long id;

    // ...
    @ManyToOne
    @JoinColumn(name = "author_id")
    private User author;
}

And I want to perform an "in" query on the author column, so I wrote my BlogRepository like:

public interface BlogRepository extends JpaRepository<Blog, Long>, CustomizedBlogRepository {

    Page<Blog> findByUserIn(Collection<User> users, Pageable pageable);
}

This works, however, I need to perform two queries for one request, that is to query the User entity from UserRepository to get Collection<User> users . Because in many situation, all I want is semantic like:

select * from blog where author_id in (some_id_list);

So is there anyway in jpa to let me perform query like below without querying the User entity?

Answer 1

The Order part of your method gets in the way. Since you don't want the results ordered, you can use this:

public interface BlogRepository extends JpaRepository<Blog, Long>, CustomizedBlogRepository {

    Page<Blog> findByUser_IdIn(Collection<Long> userId, Pageable pageable);
}

Answer 2

Yes you can also write custom JPQL

public interface BlogRepository extends JpaRepository, CustomizedBlogRepository {

@Query("select b from Blog b LEFT JOIN b.author.authorId in :authorIds")
Page<Blog> getByUsersByIds(List<Integer> authorIds, Pageable pageable);

}

Here you can change authorId to any Id of User table, which you have created.And you can also try JOIN instead of LEFT JOIN