Question

我在一个项目中使用JPA，该项目使用Spring Data和Hibernate的Criteria API。使用JpaSpecificationExecutor我能够创建一些查询，让我可以使用Specification在我的存储库中同时使用过滤和分页，只需调用Page<EventPost> findAll(Specification<EventPost> specification, Pageable pageable);即可。

我现在遇到的问题是，我无法在没有hibernate的情况下对结果进行排序，从而产生像这样的无效查询：

select count(eventpost0_.event_id) as col_0_0_ from event_post eventpost0_ where eventpost0_.category_event_category_id=? order by eventpost0_.createDate desc

显然，Hibernate必须在发出真正的查找器查询之前对行进行计数，并错误地将我的Criteria中的order by子句添加到select count(*)语句中。

这是我在日志中看到的逐字：

2016-09-05 09:22:36.987 [http-bio-8080-exec-4] DEBUG org.hibernate.SQL - select count(eventpost0_.event_id) as col_0_0_ from event_post eventpost0_ where eventpost0_.category_event_category_id=? order by eventpost0_.createDate desc
2016-09-05 09:22:36.991 [http-bio-8080-exec-4] WARN  o.h.e.j.spi.SqlExceptionHelper - SQL Error: 0, SQLState: 42803
2016-09-05 09:22:36.992 [http-bio-8080-exec-4] ERROR o.h.e.j.spi.SqlExceptionHelper - ERROR: column "eventpost0_.createdate" must appear in the GROUP BY clause or be used in an aggregate function
  Position: 133

这就是我创建查询的方式

@Override
public Predicate toPredicate(Root<EventPost> root, CriteriaQuery<?> query, CriteriaBuilder cb) {
        Path<EventPost> category = root.get("category");
        Path<Long> participants = root.get("participants");
        Path<EventPostType> eventPostType = root.get("eventPostType");

        final List<Predicate> predicates = new ArrayList<Predicate>();

        if(criteria.getEventCategory()!=null){
            predicates.add(cb.equal(category,criteria.getEventCategory()));
        }

        if(criteria.getParticipantsFrom()!=null){
            predicates.add(cb.ge(participants,criteria.getParticipantsFrom()));
        }else if(criteria.getParticipantsTo()!=null){
            predicates.add(cb.lt(participants,criteria.getParticipantsTo()));
        }

        if(criteria.getEventPostType()!=null){
            predicates.add(cb.equal(eventPostType,criteria.getEventPostType()));
        }

        query.orderBy(cb.desc(root.get("createDate")));

        return cb.and(predicates.toArray(new Predicate[predicates.size()]));
}

当我删除query.orderBy(cb.desc(root.get("createDate")));时，一切正常。任何想法在这里可能有什么问题？

版本如下：

PostgreSQL Database 9.5.3.0 with PostGIS
spring-orm:jar:4.2.5.RELEASE
spring-data-jpa:jar:1.9.4.RELEASE
hibernate-spatial:jar:4.3:compile
hibernate-core:jar:4.3.11.Final:compile
postgresql:jar:8.4-701.jdbc4:compile
postgis-jdbc:jar:1.5.2:compile

Answer 1

I have the following code which worked for me 

CriteriaBuilder cb = em.getCriteriaBuilder();
    CriteriaQuery<T> cq = cb.createQuery(entity);
    Root<T> root = cq.from(entity);

 cq.orderBy(cb.desc(cb.sum(root.get(orderByString))));

// orderByString is string entity field that is being aggregated and which we want to put in orderby clause as well.

使用orderBy（）时，Hibernate Criteria API会生成带有聚合的无效SQL

1 个答案: