来自2个表和Spring数据JPA的自定义查询

例外情况：

org.springframework.core.convert.ConverterNotFoundException: No converter found capable of converting from type [org.springframework.data.jpa.repository.query.AbstractJpaQuery$TupleConverter$TupleBackedMap] to type [model.pojo.CarPrice]

我有两张桌子

+------------------+--------------+------+-----+---------+----------------+
| Field            | Type         | Null | Key | Default | Extra          |
+------------------+--------------+------+-----+---------+----------------+
| car_id           | int(11)      | NO   | PRI | NULL    | auto_increment |
| car_brand        | varchar(255) | NO   |     | NULL    |                |
| car_model        | varchar(255) | YES  |     | NULL    |                |
| car_plate_number | varchar(255) | NO   |     | NULL    |                |
| car_type         | varchar(255) | YES  |     | NULL    |                |
+------------------+--------------+------+-----+---------+----------------+

及

我试图从车上获取全部数据和部分CarRentDetails

在我的随身携带中

@Repository
public interface CarRepository extends JpaRepository<Car, Integer> {

    String ALL_AVAILIABLE_CAR_LIST_PRICE = " SELECT c.car_id, c.car_brand, c.car_model, 
     c.car_plate_number, c.car_type, crd.cost_per_day, crd.avaliable_to_rent " +
            " FROM car_info c " +
            " JOIN car_rent_details crd" +
            " ON c.car_id = crd.car_rent_details_id" +
            " AND crd.avaliable_to_rent = true ";

    @Query(value = ALL_AVAILIABLE_CAR_LIST_PRICE, nativeQuery = true)
    List<CarPrice> findAllByAvaliablePrice();

---

如何从该查询映射对象？

创建投影界面而不是POJO

public interface CarPrice {
    Integer getCarId();
    String getCarBrand();
    String getCarModel();
    String getCarPlateNumber();
    CarType getCarType();
    double getCostPerDay();
    boolean isAvaliableToRent();
}

并格式化查询，以返回符合投影接口getter的字段（带别名的映射）

String ALL_AVAILIABLE_CAR_LIST_PRICE = " SELECT c.car_id AS carId, c.car_brand AS carBrand, c.car_model AS carModel, 
     c.car_plate_number AS carPlateNumber, c.car_type AS carType, crd.cost_per_day AS costPerDay, crd.avaliable_to_rent AS avaliableToRent" +
            " FROM car_info c " +
            " JOIN car_rent_details crd" +
            " ON c.car_id = crd.car_rent_details_id" +
            " AND crd.avaliable_to_rent = true ";

@Query(value = ALL_AVAILIABLE_CAR_LIST_PRICE, nativeQuery = true)
List<CarPrice> findAllByAvaliablePrice();

String ALL\u available\u CAR\u LIST\u PRICE=“选择c.CAR\u id作为carId，选择c.CAR\u品牌作为carBrand，选择c.CAR\u车型作为carModel，
c、 汽车车牌号为车牌号，c.汽车类型为车型，crd.每日成本为每日成本，crd.可供出租为可供出租”+
“来自汽车信息中心”+
“加入汽车租赁详细信息crd”+
“在c.car\u id=crd.car\u rent\u details\u id上”+
“和crd.available\u to\u rent=true”；
@查询（值=所有可用车辆列表价格，nativeQuery=true）
列出FindAllByAvailablePrice（）；

---

希望这有帮助

谢谢，这帮了大忙。你知道什么定义了顺序吗？首先是哪个变量？我的Json现在看起来是这样的：{“carPlateNumber”：“ZS11110”，“carId”：1，“carType”：“CLASSIC”，“AvailableTorent”：true，“carBrand”：“VOLVO”，“carModel”：“V40”，“costPerDay”：89.0}但如果是这样的话更好：{carId carBrand carModel carPlateNumber costPerDay AvailableTorent}第二个json反映了我的投影界面中的顺序。如何将顺序重新排列为Json可能与第二个类似？只需在接口

CarPrice

上为Json属性顺序指定注释，如

@JsonPropertyOrder（{“carId”、“carBrand”、“carModel”、“carPlateNumber”、“costPerDay”、“availabletorent”}）

。如果符合您的目的，请将答案标记为已接受。

public interface CarPrice {
    Integer getCarId();
    String getCarBrand();
    String getCarModel();
    String getCarPlateNumber();
    CarType getCarType();
    double getCostPerDay();
    boolean isAvaliableToRent();
}

String ALL_AVAILIABLE_CAR_LIST_PRICE = " SELECT c.car_id AS carId, c.car_brand AS carBrand, c.car_model AS carModel, 
     c.car_plate_number AS carPlateNumber, c.car_type AS carType, crd.cost_per_day AS costPerDay, crd.avaliable_to_rent AS avaliableToRent" +
            " FROM car_info c " +
            " JOIN car_rent_details crd" +
            " ON c.car_id = crd.car_rent_details_id" +
            " AND crd.avaliable_to_rent = true ";

@Query(value = ALL_AVAILIABLE_CAR_LIST_PRICE, nativeQuery = true)
List<CarPrice> findAllByAvaliablePrice();