Java 使用 JPA Criteria builder 进行复杂查询
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Complex queries with JPA Criteria builder
提问by Aina Ari
Can someone suggest me how to build up the following query using JPA Criteria builder API?
有人可以建议我如何使用 JPA Criteria builder API 构建以下查询吗？
SELECT id,status,created_at from transactions where status='1'
and currency='USD' and appId='123' order by id
It's better if I can find a solution which creates dynamically based on the parameters given as a Map<String,String>using metamodel classes or any other way.
如果我能找到一种解决方案，该解决方案根据作为Map<String,String>使用元模型类或任何其他方式给出的参数动态创建，那就更好了。
采纳答案by axtavt
It's like this (without metamodel):
是这样的（没有元模型）：
Map<String, Object> params = ...;
CriteriaBuilder cb = em.getCriteriaBuilder();
CriteriaQuery<Tuple> cq = cb.createTupleQuery();
Root<Transaction> r = cq.from(Transaction.class);
Predicate p= cb.conjunction();
for (Map.Entry<String, Object> param: params.entrySet())
p = cb.and(p, cb.equal(r.get(param.getKey()), param.getValue()));
cq.multiselect(r.get("id"), r.get("status"), r.get("created_at"))
.where(p)
.orderBy(cb.asc(r.get("id")));
List<Tuple> result = em.createQuery(cq).getResultList();
Or with metamodel (typesafe, but a bit wordy):
或者使用元模型（类型安全，但有点罗嗦）：
Map<SingularAttribute<Transaction, ?>, Object> params = ...;
CriteriaBuilder cb = em.getCriteriaBuilder();
CriteriaQuery<Tuple> cq = cb.createTupleQuery();
Root<Transaction> r = cq.from(Transaction.class);
Predicate p= cb.conjunction();
for (Map.Entry<SingularAttribute<Transaction, ?>, Object> param: params.entrySet())
p = cb.and(p, cb.equal(r.get(param.getKey()), param.getValue()));
cq.multiselect(r.get(Transaction_.id), r.get(Transaction_.status),
r.get(Transaction_.created_at))
.where(p)
.orderBy(cb.asc(r.get(Transaction_.id)));
List<Tuple> result = em.createQuery(cq).getResultList();
