是否可以调用本机查询并将结果集存储在非实体对象中？

Question

我正在尝试使用本机查询获取非实体对象，我想将其用作应用程序中某个页面上的视图模型。 我正在关注this 的解释，它没有详细说明，对于已经熟悉该主题并且只需要提醒的人来说，它更像是一个备忘单。 很久以前就有类似的问题here 和here，因为我不知道所提供的代码块应该去哪里，所以我想我可能会问一个新问题。 无论我尝试什么，我都会得到这个异常：

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

这是我的模型类：

public class ProductForHomeView {

    private int id;
    private String title;
    private EProductType productType;
    private double price;
    private int quantity;

    public ProductForHomeView(int id, String title, EProductType productType, double price, int quantity) {
        this.id = id;
        this.title = title;
        this.productType = productType;
        this.price = price;
        this.quantity = quantity;
    }

存储库界面：

public interface IProductsRepository extends CrudRepository<Products, Integer> {
    @Query(value = "SELECT products.id, products.title, products.the_type AS productType, stock.price, stock.quantity FROM products LEFT JOIN stock on products.id=stock.product_id", nativeQuery = true)
    List<ProductForHomeView> getProductsInfoForTheHomePage();   
}

我尝试映射非实体类的实体类之一：

@Entity
@Table(name = "stock")
@SqlResultSetMapping(
        name="ProductForHomeViewMapping",
        classes={
        @ConstructorResult(
        targetClass=qualified.name.ProductForHomeView.class,
        columns={
        @ColumnResult(name="id", type=Integer.class),
        @ColumnResult(name="title", type=String.class),
        @ColumnResult(name="productType", type=EProductType.class),
        @ColumnResult(name="price", type=Long.class),
        @ColumnResult(name="quantity", type=String.class)
        })})
public class Stock {
// mapped fields, constructors, geters and setters...
}

感谢您的任何意见！

Answer 1

我使用@SqlResultSetMapping 和@NamedNativeQuery

使用以下方法更改您的 Curd 存储库方法

public interface IProductsRepository extends CrudRepository<Products, Integer> {
    @NamedNativeQuery(value = "SELECT products.id, products.title, products.the_type AS productType, stock.price, stock.quantity FROM products LEFT JOIN stock on products.id=stock.product_id", resultSetMapping = "ProductForHomeViewMapping")
    List<ProductForHomeView> getProductsInfoForTheHomePage();   
}

更多信息可here

Answer 2

你可以将你的视图声明为一个接口，然后 Spring Data 会按照你想要的方式处理它。

示例如下：

https://github.com/roberthunt/spring-data-native-query-projection/blob/master/src/main/java/uk/co/rbrt/PersonSummary.java

https://github.com/roberthunt/spring-data-native-query-projection/blob/master/src/main/java/uk/co/rbrt/PersonRepository.java