Spring Data MongoDB-在使用存储库查询的响应中，长值为空

问题描述

我正在使用V2.4.5开发Spring Boot MongoDB示例。在本例中，当我执行存储库查询时，没有映射长字段值。来自MongoDB的文档值示例。

{
    "_id" : ObjectId("60a536412306ab5bdd7a6b06"),
    "user" : {
        "id" : 1,
        "firstname" : "vins",
        "lastname" : "guru",
        "email" : "[email protected]"
    },
    "product" : {
        "id" : 1,
        "description" : "ipad"
    },
    "price" : 300
}

OrderController.java

@RestController
@RequestMapping("/order-service")
public class OrderController {
    @Autowired
    private PurchaseOrderService purchaseOrderService;

    @GetMapping("/all")
    public List<PurchaseOrder> getAllOrders() {
        return this.purchaseOrderService.getPurchaseOrders();
    }

    @PostMapping("/create")
    public void createOrder(@RequestBody PurchaseOrder purchaseOrder) {
        this.purchaseOrderService.createPurchaseOrder(purchaseOrder);
    }
}

Purche eOrderServiceImpl.java

@Service
public class PurchaseOrderServiceImpl implements PurchaseOrderService {

    @Autowired
    private PurchaseOrderRepository purchaseOrderRepository;

    @Override
    public List<PurchaseOrder> getPurchaseOrders() {
        return this.purchaseOrderRepository.findAll();
    }

    @Override
    public void createPurchaseOrder(PurchaseOrder purchaseOrder) {
        this.purchaseOrderRepository.save(purchaseOrder);
    }

}

PurcheseOrder.java

@AllArgsConstructor
@NoArgsConstructor
@Data
@Builder
@Document(collection = "purchase_order")
public class PurchaseOrder {
    @Id
    private Long id;
    private User user;
    private Product product;
    private double price;
}

User.java

@AllArgsConstructor
@NoArgsConstructor
@Data
@Builder
public class User {
    private Long id;
    private String firstname;
    private String lastname;
    private String email;
}

Product.java

@AllArgsConstructor
@NoArgsConstructor
@Data
@Builder
public class Product {
    private Long id;
    private String description;
}

我得到的输出是

{
    "_id" : ObjectId("60a536412306ab5bdd7a6b06"),
    "user" : {
        "id" : null,
        "firstname" : "vins",
        "lastname" : "guru",
        "email" : "[email protected]"
    },
    "product" : {
        "id" : null,
        "description" : "ipad"
    },
    "price" : 300
}

Purche eRepository.Java

public interface PurchaseOrderRepository extends MongoRepository<PurchaseOrder, String> {
    @Query("{ 'user.id': ?0 }")
    List<PurchaseOrder> findByUserId(Long userId);
}

推荐答案

为什么会得到空，mongodb默认的id字段是_id。而在任何类中，Spring data都会将id转换为_id。当您尝试运行时，可以查看控制台find using query: { "user._id" : 1} fields: Document{{}}。它也提到了_id，没有映射到数据库，数据库有id。(不带下划线)。要克服此问题，您可以使用@Field。

public class User {
    @Field("id")
    private Long id;
    private String firstname;
    private String lastname;
    private String email;
}

或者您可以在任何地方(在类和集合中)使用_id

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