Spring Data'Left Join Fetch'查询返回null

Question

我的查询如下所示:

@Query("SELECT p FROM Pilot p LEFT JOIN FETCH p.playerShips WHERE p.nickname = (:nickname)")

到现在为止还挺好.即使playerShips为空,我也会获得Pilot实例.
现在,我想只获取不活动的船只,所以我修改了我的查询,如下所示:

@Query("SELECT p FROM Pilot p LEFT JOIN FETCH p.playerShips s WHERE p.nickname = (:nickname) AND s.active = false")

我作为一名飞行员得到了空,所以它显然不起作用.
如果有人能解释如何使用适用于子元素的WHERE子句创建JOIN FETCH查询,我会很高兴.提前致谢.

Answer 1

经过大量研究后，我决定实现一个自定义存储库，以便我可以使用 Hibernate Filters，现在它可以工作了。

试点存储库：

@Repository
public interface PilotRepository extends JpaRepository<Pilot, Long>, PilotRepositoryCustom{
/*spring data methods here*/
}

PilotRepository自定义：

public interface PilotRepositoryCustom {
    public Pilot findByNicknameFetchInactiveShips(String nickname);
}

PilotRepositoryImpl：

public class PilotRepositoryImpl implements PilotRepositoryCustom{

    @PersistenceContext
    EntityManager entityManager;

    @Override
    public Pilot findByNicknameFetchInactiveShips(String nickname) {
        Session session = entityManager.unwrap(Session.class);
        session.enableFilter("active").setParameter("active", false);
        Query query = entityManager.createQuery(
                "SELECT p FROM Pilot p " +
                "LEFT JOIN FETCH p.playerShips ps " +
                "LEFT JOIN FETCH ps.ship s " +
                "WHERE p.nickname = (:nickname)");
        query.setParameter("nickname", nickname);
        return (Pilot)query.getSingleResult();
    }
}

这就是 Spring 数据。现在过滤器配置：

Pilot 实体：

    @OneToMany(fetch = FetchType.LAZY, mappedBy = "pilot")
    @Filter(name="active", condition = "active = :active")
    private List<PlayerShip> playerShips;

PlayerShip 实体：

@Entity
@Table(name="player_ship")
@FilterDef(name="active", parameters=@ParamDef(name="active",type="java.lang.Boolean"))
public class PlayerShip {
    /*...*/
    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "pilot_id")
    private Pilot pilot;
    /*...*/
}

重要提示：
如果您在 @ParamDef 中使用 Boolean，请确保键入java.lang.Boolean而不仅仅是Boolean。我花了一个多小时想知道为什么我不断收到参数未找到/未定义错误。