java - Spring 数据休息:How to select specific field from the repository

Question

在下面的查询中，我只想从订单中选择shopname，但是当我执行查询时，它给我一个错误PersistentEntity can not be null我已经搜索过这个问题但找不到任何解决方案如何仅从订单表中获取选定的行？

订单存储库

public interface OrderRepository extends JpaRepository<Order, Long> {
@Query("Select o.shopName from Order o where o.customer.id= :customerId ")
     String selectUsersOrder(@Param("customerId") Long customerId );
}

订单.class

@Entity
@Table(name="CustomerOrder")
public class Order implements Serializable,OrderGetters {
    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @Column( nullable = false, updatable = false, insertable = false, columnDefinition = "TIMESTAMP DEFAULT CURRENT_TIMESTAMP")
    @Temporal(TemporalType.TIMESTAMP)
    private Date orderDate ;

    @OneToMany(mappedBy="order",targetEntity=OrderItem.class)
    private List<OrderItem> orderitem;

    @Temporal(TemporalType.TIMESTAMP)
    private Date completionDate ;

    @Enumerated(EnumType.STRING)
    private OrderStatus orderStatus;

    @Enumerated(EnumType.STRING)
    private DeliveryStatus deliveryStatus;



    private String riderInstruction;

    @Enumerated(EnumType.STRING)
    private OrderType orderType;

    @ManyToOne
    private User customer;


    @OneToOne
    private User rider;

    @OneToOne
    private Address dropOffAddress;

    @OneToOne
    private Address pickupAddress;

    private String receiverName;

    private String promoCode;

    private String shopName;

    private float shoppingPrice;

    private float orderPrice;

    private float cashCollected;

    ..... Getter and setters
    }

Answer 1

您可以通过将nativeQuery值设置为“true”来使用Spring的nativeQuery属性:

@Query("SELECT ShopName FROM CustomerOrder WHERE CustomerId = ?1", nativeQuery = true)
String selectUsersOrder(Long customerId);

或者您可以在获取时先将其转换为 Object[]，然后从该对象中获取您想要的值。