JPA 2没有明确的选择,也没有确定隐含的感冒

Question

我正在尝试获取在特定日期之后创建用户的文件夹的所有用户.用户和文件夹之间的关系存在于单独的表中.

这是我提出的查询,但是这个例外就是一个例子

没有明确的选择和隐含的感冒不被确定

代码

@Override
public List<RetailPostUserTbl> getNewUsersForSiteSince( Date date, Integer siteId )
{
    List<RetailPostUserTbl> toReturn = new ArrayList<RetailPostUserTbl>();
    EntityManager em = getEntityManager();
    CriteriaBuilder cb = em.getCriteriaBuilder();

    Class<RpUserFolderMapTbl> userFolderPC = userFolderMapDAO.getPersistentClass();

    CriteriaQuery<RpUserFolderMapTbl> mapQuery = cb.createQuery( userFolderPC );
    Root<RpUserFolderMapTbl> root = mapQuery.from( userFolderPC );
    Path<Integer> folderIdPath = root.get( RpUserFolderMapTbl_.folder ).get( FolderTbl_.folderId );

    Predicate folderCondition = cb.equal( folderIdPath, siteId );

    Subquery<RetailPostUserTbl> rpSubQ = mapQuery.subquery( persistentClass );
    Root<RetailPostUserTbl> subQRoot = rpSubQ.from( persistentClass );
    Path<UserTbl> userPath = subQRoot.get( RetailPostUserTbl_.user );
    Path<Date> userCreatedPath = userPath.get( UserTbl_.userCreateDate );
    Predicate userCreateDateCondition = cb.greaterThanOrEqualTo( userCreatedPath, date );
    rpSubQ.where( userCreateDateCondition );

    mapQuery.where( cb.and( folderCondition, cb.exists( rpSubQ ) ) );

    TypedQuery<RpUserFolderMapTbl> query = em.createQuery( mapQuery );
    List<RpUserFolderMapTbl> results = query.getResultList();
    for ( RpUserFolderMapTbl result : results )
    {
        RetailPostUserTbl rpuser = result.getUser().getRetailPostUser();
        toReturn.add( rpuser );
    }
    return toReturn;
}

任何人都知道为什么这不起作用？

Answer 1

您还应该为"子查询"明确设置选择.

rpSubQ.select(subQRoot);

Answer 2

我今天遇到了完全相同的错误.有趣的是,我从Hibernate 3.6.3.Final docs中抓住了我的例子.他们的例子是:

CriteriaQuery query = builder.createQuery();
Root<Person> men = query.from( Person.class );
Root<Person> women = query.from( Person.class );
Predicate menRestriction = builder.and(
    builder.equal( men.get( Person_.gender ), Gender.MALE ),
    builder.equal( men.get( Person_.relationshipStatus ), RelationshipStatus.SINGLE )
);
Predicate womenRestriction = builder.and(
    builder.equal( women.get( Person_.gender ), Gender.FEMALE ),
    builder.equal( women.get( Person_.relationshipStatus ), RelationshipStatus.SINGLE )
);
query.where( builder.and( menRestriction, womenRestriction ) );

我所做的"修复"错误是明确选择根.注意我必须创建一个root来解决这个问题.这是我的例子:

CriteriaQuery query = builder.createQuery();
Root<Person> personRoot = query.from( Person.class );
Predicate menRestriction = builder.and(
    builder.equal( personRoot.get( Person_.gender ), Gender.MALE ),
    builder.equal( personRoot.get( Person_.relationshipStatus ), RelationshipStatus.SINGLE )
);
Predicate womenRestriction = builder.and(
    builder.equal( personRoot.get( Person_.gender ), Gender.FEMALE ),
    builder.equal( personRoot.get( Person_.relationshipStatus ), RelationshipStatus.SINGLE )
);
query.select(personRoot);
query.where( builder.and( menRestriction, womenRestriction ) );

我无法弄清楚为什么不能进行隐式选择.在Hibernate的示例中,唯一使用的类是Person.class.当我进一步挖掘时,我会更新我的回复.