Question

在以下查询中，我只想从订单中选择shopname但是当我执行查询时，它会给我一个错误PersistentEntity must not be null 我搜索过这个问题，但我找不到任何解决方案如何只从Order表中获取选定的行？

OrderRepository

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 );
}

Order.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＆＃39; true＆＃39;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首先将其强制转换为Object []，而不是从此对象中获取所需的值。

Answer 2

您应该使用Projection并从回购中删除自定义方法。

@Projection(name = "onlyShopName", types = {Order.class})
public interface OnlyShopName { 

    String getShopName();
}

然后按照以下方式获取您的订单：

GET http://localhost:8080/orders?projection=onlyShopName

SPRING数据REST：如何从存储库中选择特定字段

2 个答案: