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[英]Why does my JpaRepository (spring-data-jpa) custom query return me an empty list?
[英]Sort On Child List total count using JpaRepository Spring-data-jpa
我需要对实体进行分页和排序。
@Entity
@Table(name = "CATEGORY", catalog = "")
public class CategoryEntity {
private CategoryEntity categoryByParentCategoryId;
private Set<CategoryEntity> categoriesByCategoryId;
@ManyToOne(fetch = FetchType.LAZY,optional = false, cascade = CascadeType.PERSIST)
@JoinColumn(name = "PARENT_CATEGORY_ID", referencedColumnName = "CATEGORY_ID")
public CategoryEntity getCategoryByParentCategoryId() {
return categoryByParentCategoryId;
}
public void setCategoryByParentCategoryId(CategoryEntity categoryByParentCategoryId) {
this.categoryByParentCategoryId = categoryByParentCategoryId;
}
@OneToMany(mappedBy = "categoryByParentCategoryId", cascade = CascadeType.PERSIST)
public Set<CategoryEntity> getCategoriesByCategoryId() {
return categoriesByCategoryId;
}
public void setCategoriesByCategoryId(Set<CategoryEntity> categoriesByCategoryId) {
this.categoriesByCategoryId = categoriesByCategoryId;
}
从此链接和其他堆栈溢出答案中,我发现可以使用Paging Request
使用排序和分页,例如
Pageable size = new PageRequest(page, paginationDTO.getSize(),Sort.Direction.ASC, "id");
我的问题是我有一个上面模型中所示的self join
父子关系,我需要根据子计数对父排序,如下所示。
在这里Number of SubCategories
categoriesByCategoryId
的Number of SubCategories
的大小。 我需要在id
中的PageRequest
中传递什么,以便根据子列表的大小进行排序。
PS。 该模型有更多字段,但为简短起见,我只发布了相关字段
经过这个答案之后,我能够通过使用自定义查询来达到要求,JPARepository中的方法看起来像
@Query(
value = "select c from CategoryEntity c " +
" WHERE LOWER(c.categoryNameEn) LIKE LOWER(CONCAT('%',?2, '%')) AND activeInd = ?1 " +
"AND c.categoryByParentCategoryId is null" +
" Order By c.categoriesByCategoryId.size desc",
countQuery = "select count(c) from CategoryEntity c " +
" WHERE LOWER(c.categoryNameEn) LIKE LOWER(CONCAT('%',?2, '%')) AND activeInd = ?1" +
" AND c.categoryByParentCategoryId is null"
)
Page<CategoryEntity> findAllActiveCategoriesByCategoriesByCategoryIdCountDesc(String activeInd, String categoryNameEn, Pageable pageable);
分页详细信息需要Count查询。
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