使用 JPA 规范无法在多对多关系中找到不具有实体的实体

Question

我希望将此查询实现为 Spring 数据存储库的规范：

select * from Parts 
 where id not in (select partId 
                    from PartsToDeliveries
                    where deliveryId = 31)

（基本上，找到不属于特定交付的所有零件）

这里是类:

@Entity
public class Part {
    @Id
    private Long id;

    @ManyToMany
    @JoinTable(name = "PartsToDeliveries", joinColumns = {@JoinColumn(name = "partId")}, inverseJoinColumns = @JoinColumn(name = "deliveryId"))
    private Set<Delivery> deliveries = new HashSet<>();
}

和

@Entity
public class Delivery {

    @Id
    private Long id;

    @ManyToMany(mappedBy = "deliveries")
    private List<Part> parts;
}

填空：

Specification<Part> specification = (root, criteriaQuery, criteriaBuilder) ->     {
    ? _______ ?
}

我根本不知道从哪里开始。

Answer 1

您可以使用 CriteriaAPI - CriteriaBuilder#not() 和 subquery()

模拟相似的语义

这里有构建类似查询的 SO 示例 JPA 2.0, Criteria API, Subqueries, In Expressions

这是 JPA 文档 http://docs.oracle.com/javaee/6/api/javax/persistence/criteria/CriteriaBuilder.html

Answer 2

类似于：

criteriaBuilder.not(root.get("deliveries").in(notWantedDelivery))

Answer 3

Antoniosss 找到了正确的解决方案（该文档并不是特别有用）。为了完整起见，这里是最终解决方案：

specification = (root, criteriaQuery, criteriaBuilder) -> {
                Subquery<Long> subquery   = criteriaQuery.subquery(Long.class);
                Root<Part>     subFrom    = subquery.from(Part.class);
                Path<Long>     deliveryId = subFrom.join("deliveries").get("id");
                subquery.select(subFrom.get("id"));
                subquery.where(criteriaBuilder.equal(deliveryId, 31l));

                Path<Long> id = root.get("id");
                return criteriaBuilder.not(criteriaBuilder.in(id).value(subquery));
            };

使用 JPA 规范无法在多对多关系中找到不具有实体的实体

Cannot find entities not having an entity in a many to many relationship using a JPA Specification

spring

hibernate

hibernate-criteria

spring-data

spring-data-jpa