[英]In Hibernate HQL, how do I left join fetch a subclass' linked entities when multiple subclasses have a property with the same name?
[英]How do I stop hibernate returning multiple instances when using “join” fetch mode?
鉴于以下情况,当我执行查询时,我试图强制加载子集合(countryData),这是可行的,但是最后我却加载了Bin
记录的副本。
public Collection<Bin> getBinsByPromotion(String season, String promotion) {
final Session session = sessionFactory.getCurrentSession();
try {
session.beginTransaction();
return (List<Bin>) session.createCriteria(Bin.class).
setFetchMode("countryData", FetchMode.JOIN).
add(Restrictions.eq("key.seasonCode", season)).
add(Restrictions.eq("key.promotionCode", promotion)).
add(Restrictions.ne("status", "closed")).
list();
} finally {
session.getTransaction().commit();
}
}
我不希望使用默认(懒惰)行为,因为查询将返回〜8k条记录,因此发送了16k条额外的查询以获取子记录。
如果没有别的我更喜欢。
select ... from bins b where b.seasonCode = ?
and b.promotionCode = ?
and b.status <> 'Closed';
select ... from binCountry bc where bc.seasonCode = ?
and bc.promotionCode = ?;
您可以使用CriteriaSpecification.DISTINCT_ROOT_ENTITY;
criteria.setResultTransformer(CriteriaSpecification.DISTINCT_ROOT_ENTITY);
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