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我在春季数据jpa中创建了left join
查询,JPQL
但在我的单元测试中失败。项目中有两个实体。在春季数据中使用JPQL加入查询Jpa
Product
实体:
@Entity
@Table(name = "t_goods")
public class Product implements Serializable {
@Id
@GeneratedValue
@Column(name = "id", length = 6, nullable = false)
private Integer id;
@Column(name = "name", length = 20, nullable = false)
private String name;
@Column(name = "description")
private String desc;
@Column(name = "category", length = 20, nullable = false)
private String category;
@Column(name = "price", nullable = false)
private double price;
@Column(name = "is_onSale", nullable = false)
private Integer onSale;
@ManyToOne(cascade = CascadeType.ALL)
@JoinColumn(name = "brand_id")
private Brand brand;
// getter and setter
}
Brand
实体:
@Entity
@Table(name = "tdb_goods_brand")
public class Brand implements Serializable {
@Id
@GeneratedValue
@Column(name = "id", length = 6, nullable = false)
private Integer id;
@Column(name = "brand_name", unique = true, nullable = false)
private String name;
@OneToMany(mappedBy = "brand", fetch = FetchType.EAGER, cascade = CascadeType.ALL)
private List<Product> products;
// getter and setter
}
而第三类Prod
映射查询结果对象:
public class Prod implements Serializable {
private Integer id;
private String name;
private double price;
//private String brandName;
// getter and setter
}
它正常工作与此查询:
public interface ProductRepository extends JpaRepository<Product, Integer> {
@Query(value = "select new com.pechen.domain.Prod(p.id, p.name, p.price) from Product p ")
Page<Prod> pageForProd(Pageable pageRequest);
}
但如果我对Prod
增加新属性brandName
与left join
重构查询时,它测试失败:
@Query(value = "select new com.pechen.domain.Prod(p.id, p.name, p.price, b.name) from Product p left join com.pechen.domain.Brand b on p.brand_id = b.id")
Page<Prod> pageForProd(Pageable pageRequest);
这个问题似乎是在这里on p.brand_id = b.id
因为没有一个brand_id
财产Product
,它只是一个列名。那我该如何做这项工作?
更新:
有原来是在JPQL
查询的一些语法时才错误,只是修复它,如下所示:
@Query(value = "select new com.pechen.domain.Prod(p.id, p.name, p.price, b.name) from Product p left join p.brand b")
Page<Prod> pageForProd(Pageable pageRequest);
此外,它以这种方式来创建另一个类很麻烦每次将查询结果映射到对象(我的意思是Prod
类)。那么有没有一种好的方法来处理它?任何帮助,将不胜感激。