如何从spring data JPA中的子主键获取父实体？

Question

    @Entity
    @Table(name = "usr")
    class User{
    @Id
    @Column(name = "user_id", updatable = false, nullable = false)
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long userId;
    private String username;
    @OneToMany(mappedBy = "user",cascade = CascadeType.ALL)
    private List<Vehicle> vehicles= new ArrayList<>();
    //getters and setters
    }

       @Entity
       @Table(name = "vehicle")
       class Vehicle{
       @Id
       @Column(name = "vehicle_id", updatable = false, nullable = false)
       @GeneratedValue(strategy = GenerationType.IDENTITY)
       private Long vehicleId;
       private String vehicleName;
       @ManyToOne(fetch = FetchType.LAZY)
       @JoinColumn(name = "user_fk" , nullable = false)
       private User user;
      //getters and setters 
      }

我有vehicleId和vehicleName的值，我想从这两个属性值中获取User对象。

我不想创建一个车辆存储库仅仅是为了找到用户对象，我知道可以通过创建一个车辆存储库来实现，它扩展了springdatajpa中的JPA存储库。

Answer 1

您可以从您的用户存储库中执行此操作，如下所示

User findByVehicles_VehicleIdAndVehicles_VehicleName(Long id, String name);

注意，如果有多个用户满足条件，这将引发异常

如果只想获取id，则必须依赖自定义查询

@Query("select u.userId from User u join u.vehicles v where v.vehicleId=?1 and v.vehicleName=?2")
Long getUserIdByVehicleIdAndName(Long id, Long name);