从一对多关系中提取记录的休眠条件

Question

我正在传递一组车辆名称，例如['car','jeep','truck','bike']，并希望使用Criteria查询在此列表中选择拥有vehicles的那些车主，这里的车主可以拥有多个vahicles（OneToMany）。我有一个限制，我需要使用条件查询。

class Owner {

    @ID
    @GeneratedValue(strategy = IDENTITY)
    @Column(name = "owner_id")
    private Long ownerId;

    @OneToMany(cascade = CascadeType.ALL)
    @JoinColumn(name = "owner_id")
    private Set<Vehicles> vehicles;

}

class Vehicles {

    @ID
    @GeneratedValue(strategy = IDENTITY)
    @Column(name = "vehicle_id")
    private Long vehicleId;

    @ManyToOne
    @JoinColumn(name = "owner_id")
    private Owner owner;

    @Column(name="vehicle_name")
    private String vehicleName;

}

以下是我尝试过但没有成功的内容

Criteria criteria = getSession().createCriteria(Owner.class);
criteria.createAlias("vehicles", "vehicles");
criteria.add(Restrictions.in("vehicles.vehicleName", setOfVehicles));
criteria.setResultTransformer(CriteriaSpecification.DISTINCT_ROOT_ENTITY);

Answer 1

首先，您的映射看起来不正确。 Owner和Vehicles之间存在双向关联。因此，只有@ManyToOne一侧应带有@JoinColumn注释。我将通过以下方式使用更正的映射：

@Entity
@Table
public class Owner
{
   @Id
   @Column(name = "own_id")
   private Long id;

   @OneToMany(mappedBy = "owner")
   private Set<Vehicles> vehicles;
}

@Entity
@Table
public class Vehicles
{
   @Id
   @Column(name = "veh_id")
   private Long id;

   @Column(name = "veh_name")
   private String name;

   @ManyToOne
   @JoinColumn(name = "veh_own_id")
   private Owner owner;
}

接下来要强调的是，您尝试使用不推荐使用的Hibernateorg.hibernate.CriteriaAPI。我将为Criteria API提供一个示例。因此，查询将具有以下视图：

CriteriaBuilder builder = session.getCriteriaBuilder();
CriteriaQuery<Owner> criteria = builder.createQuery(Owner.class);
Root<Owner> root = criteria.from(Owner.class);
ListJoin<Owner, Vehicles> vehs = (ListJoin<Owner, Vehicles>) root.fetch(Owner_.vehicles);

criteria
   .select(root)
   .distinct(true)
   .where(
      vehs.get(Vehicles_.NAME).in(Arrays.asList("car", "jeep", "truck", "bike"))
   );

List<Owner> deps = session.createQuery(criteria).getResultList();

Owner_和Vehicles_类属于所谓的JPA static metamodel。