常见问题汇总（十七）——关于spring data jpa

深藏阁楼爱情的钟 2022-05-18 19:59 220阅读 0赞

**1、如何实现排序**

a 命名查询：

public interface ParamsRepository extends JpaRepository<CwParams, String>,JpaSpecificationExecutor<CwParams> {
    
    	List<CwParams> findAllByOrderByCodeDesc();//根据code倒序查询
    
    }

b 基于Sort:

public ResponseResult listRecord(RecordCondition condition) {
    
            LocalResponseResult responseResult = super.buildResponseResult(condition);
            Pageable pageable = new PageRequest(condition.getPage() - 1, condition.getSize(),new Sort(Sort.Direction
                    .DESC,"id"));//创建分页条件和排序条件
    
            Specification<CwStopRecord> specification = (Specification<CwStopRecord>) (root, query, cb) -> {
    
                List<Predicate> list = new ArrayList<>();
                //条件全为空则执行无条件查询
    
                if (StringUtils.isNotBlank(condition.getType())) {
                    Predicate p1 = cb.equal(root.get("type"), condition.getType());
                    list.add(p1);
                }
                if (StringUtils.isNotBlank(condition.getCarNo())) {
                    Predicate p2 = cb.like(root.get("carNo"), "%" + condition.getCarNo() + "%");
                    list.add(p2);
                }
                if (StringUtils.isNotBlank(condition.getPhone())) {
                    Predicate p3 = cb.like(root.get("phone"), "%" + condition.getPhone() + "%");
                    list.add(p3);
                }
                if (StringUtils.isNotBlank(condition.getStallNo())) {
                    Predicate p4 = cb.like(root.get("stallNo"), "%" + condition.getStallNo() + "%");
                    list.add(p4);
                }
                if (StringUtils.isNotBlank(condition.getGardName())) {
                    Predicate p5 = cb.like(root.get("gardName"), "%" + condition.getGardName() + "%");
                    list.add(p5);
                }
    
                return cb.and(list.toArray(new Predicate[0]));
            };
    
            Page<CwStopRecord> page = stopRecordRepository.findAll(specification, pageable);
            Map<String, Object> result = new HashMap<>();
            result.put("total", page.getTotalElements());
            result.put("rows", page.getContent());
            return responseResult.result(HttpStatus.OK, result);
        }

**2、Caused by: javax.persistence.TransactionRequiredException: Executing an update/delete query**

在service层没有在对应的方法上添加事物注解导致

**3、JPA注解查询的两种参数注入方式**

a   ?参数位置

@Query(value = "select name,author,price from Book b where b.price>?1 and b.price<?2")
    List<Book> findByPriceRange(long price1, long price2);

b   :参数名

@Query(value = "select name,author,price from Book b where b.name = :name AND b.author=:author AND b.price=:price")
    List<Book> findByNamedParam(@Param("name") String name, @Param("author") String author,
            @Param("price") long price);