如何过滤具有子列表的父对象和具有孙子列表的子对象并通过匹配孙子的属性

Question

对象层次如下。

CoverCategory 有多个 Cover，一个 Cover 有多个 SubCover。 让我们在编码中这样说

封面类别

@Entity
public class CoverCategory {

@Id
private Long id;

@OneToMany
List<Cover> coverList;

}

封面

@Entity
public class Cover {

 @Id
 private Long id;

 @ManyToOne
 private CoverCategory coverCategory;

 @OneToMany
 private List<SubCover> subCoverList;

}

副封面

@Entity
public class SubCover {

       @Id
       private Long id;

       @ManyToOne
       private Cover cover;

       private String name;
}

我在这里尝试做的是选择所有具有子封面名称“subcover1”的封面类别

我尝试编写如下代码

String name = "subcover1";
Session session = getCurrentSession();
CriteriaBuilder criteriaBuilder = session.getCriteriaBuilder();
CriteriaQuery<CoverCategory> creteriaQuery = criteriaBuilder.createQuery(CoverCategory.class);
Root<CoverCategory> root = creteriaQuery.from(CoverCategory.class);
creteriaQuery.select(root).where(criteriaBuilder.equal(root.get("coverList").get("subCoverList").get("name"),name));
Query<CoverCategory> query = session.createQuery(creteriaQuery);
List<CoverCategory> results = query.getResultList();

但它给了我以下异常

org.springframework.dao.InvalidDataAccessApiUsageException: Illegal attempt to dereference path source [null.coverList] of basic type; nested exception is java.lang.IllegalStateException: Illegal attempt to dereference path source [null.coverList] of basic type  

谁能告诉我如何正确地做到这一点。提前致谢。 只需要在标准生成器中完成

Answer 1

CriteriaBuilder criteriaBuilder = em.getCriteriaBuilder();
CriteriaQuery<CoverCategory> criteriaQuery = criteriaBuilder.createQuery(CoverCategory.class);
Root<CoverCategory> root = criteriaQuery.from(CoverCategory.class);
Join<CoverCategory,Cover> coverJoin = root.join("coverList");
Join<Cover, SubCover> subjoin = coverJoin.join("subCoverList");
criteriaBuilder.equal(subjoin.get("name"),name);
Query<CoverCategory> query = session.createQuery(criteriaQuery);
List<CoverCategory> results = query.getResultList();