等价条件查询命名查询 [英] Equivalent criteria query for named query
本文介绍了等价条件查询命名查询的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
@NamedQuery(
name =Cat.favourites,
query =从Usercat中选择c
作为uc
内部连接uc.cat作为c
其中uc.isFavourtie = true
和uc.user =:user)
实现调用如下所示:
Session session = sessionFactory.getCurrentSession();
Query query = session.getNamedQuery(Cat.favourites);
query.setEntity(user,myCurrentUser);
返回query.list();
返回猫列表的等效条件查询是什么?
$ b $使用JPA 2.0标准:(这是使用JPA 2.0 Criteria API可以实现这一目标的众多方法之一) b
$ b
final CriteriaQuery< Cat> cq = getCriteriaBuilder()。createQuery(Cat.class);
final CriteriaBuilder cb = entityManager.getCriteriaBuilder();
最终Root< Usercat> uc = cq.from(Usercat.class);
cq.select(uc.get(cat);
Predicate p = cb.equal(uc.get(favourtie,true);
p = cb.and(p,cb.equal(uc.get(user),user));
cq.where(p);
final TypedQuery< Cat> typedQuery = entityManager.createQuery(cq);
返回typedQuery.getResultList();
My named query looks like this, thanks to here.
@NamedQuery(
name="Cat.favourites",
query="select c
from Usercat as uc
inner join uc.cat as c
where uc.isFavourtie = true
and uc.user = :user")
And the call to implement looks like this :
Session session = sessionFactory.getCurrentSession();
Query query = session.getNamedQuery("Cat.favourites");
query.setEntity("user", myCurrentUser);
return query.list();
What would be the equivalent criteria query that returns a list of cats ?
解决方案
With JPA 2.0 Criteria: (This is one of the many ways you can achieve this using JPA 2.0 Criteria api)
final CriteriaQuery<Cat> cq = getCriteriaBuilder().createQuery(Cat.class);
final CriteriaBuilder cb = entityManager.getCriteriaBuilder();
final Root<Usercat> uc= cq.from(Usercat.class);
cq.select(uc.get("cat");
Predicate p = cb.equal(uc.get("favourtie", true);
p = cb.and(p, cb.equal(uc.get("user"), user));
cq.where(p);
final TypedQuery<Cat> typedQuery = entityManager.createQuery(cq);
return typedQuery.getResultList();
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