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JpaSpecificationExecutor实现关联查询

2019-02-21 16:57 232 查看

JpaSpecificationExecutor实现关联查询

记录一次错误

在写一个项目的时候发现值一直无法传到前台,仔细查看原来是排序规则写错了,项目用的是layui框架:
后台:

public interface BookDao extends JpaRepository<Book, Integer> , JpaSpecificationExecutor<Book> {
Page<Book> findAll(Specification<Book> specification, Pageable pageable);
}

继承JpaSpecificationExecutor接口

public LayuiPage<Book> showBookList(@RequestParam(name ="name",required = false)String name,
@RequestParam(name = "page", required = false, defaultValue = "0") int pageNum,
@RequestParam(name = "limit", required = false, defaultValue = "20") int pageSize) {
return new LayuiPage<>(bookDao.findAll((Specification<Book>) (root, criteriaQuery, cb) -> {
List<Predicate> predicates = new ArrayList<>();
if (!StringUtils.isEmpty(name)) predicates.add(cb.or(cb.like(root.get("bookName").as(String.class), "%" + name + "%"),
cb.like(root.get("bookAuthor").as(String.class), "%" + name + "%")));
Predicate[] aryPredicates = new Predicate[predicates.size()];
criteriaQuery.where(predicates.toArray(aryPredicates));
return cb.and(aryPredicates);
}, PageRequest.of(pageNum > 0 ? pageNum - 1 : 0, pageSize, new Sort(Sort.Direction.ASC, "bookId"))));
}

Layui是自己写的页面返回类
过程中把排序规则写错了,应该为实体类的ID而非表中的字段

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