public enum ReportStatus {
SUCCCEED, FAILED;
}
public class Work {
@ElementCollection
@Enumerated(EnumType.STRING)
List<ReportStatus> reportStatuses;
}
给定以下结构,我想执行查询以查找由 reportStatuses 过滤的所有工作。它适用于以下 hql 语法:
public List<Long> queryHQL() {
final String query = "SELECT w.id FROM Work w JOIN w.reportStatuses s WHERE s in (:rs)";
final List<ReportStatus> reportStatuses = new ArrayList<ReportStatus>();
reportStatuses.add(ReportStatus.FAILED);
return this.entityManager.createQuery(query).setParameter("rs", reportStatuses).getResultList();
}
但我想使用标准 API (jpa2),但不知道该怎么做。这是我认为最接近的尝试:
public List<Long> query() {
final List<ReportStatus> reportStatuses = new ArrayList<ReportStatus>();
reportStatuses.add(ReportStatus.FAILED);
final CriteriaBuilder builder = this.entityManager.getCriteriaBuilder();
final CriteriaQuery<Long> criteriaQuery = builder.createQuery(Long.class);
final Root<Work> workModel = criteriaQuery.from(Work.class);
final ListJoin<Work, ReportStatus> status = workModel.joinList("reportStatuses");
final Predicate predicate = status.in(reportStatuses);
criteriaQuery.where(predicate);
criteriaQuery.select(workModel.<Long> get("id"));
return this.entityManager.createQuery(criteriaQuery).getResultList();
}
我也尝试过使用 hibernate criteria API,但是作为 jpa2,我没能找到正确的语法。
最佳答案
我会使用以下 CriteriaQuery 语法来做同样的事情。
EntityManager em = entityManagerFactory.createEntityManager();
final List<ReportStatus> reportStatuses = new ArrayList<ReportStatus>();
reportStatuses.add(ReportStatus.FAILED);
final CriteriaBuilder builder = em.getCriteriaBuilder();
final CriteriaQuery<Long> criteriaQuery = builder.createQuery(Long.class);
final Root<Work> _work = criteriaQuery.from(Work.class);
/*final ListJoin<Work, ReportStatus> status = _work.joinList("reportStatuses");
final Predicate predicate = status.in(reportStatuses);
criteriaQuery.where(predicate);*/
final Expression<List<ReportStatus>> _status = _work.get(Work_.reportStatuses);
_status.in(reportStatuses);
criteriaQuery.select(_work.get(Work_.id));
List<Long> list = em.createQuery(criteriaQuery).getResultList();
更新
Thanks, but we do not use the generated metamodel. So unfortunately I can't try with your answer. :(
如果您不使用 Metamodel,只需将 _work.get(Work_.reportStatuses)
替换为 _work.get("reportStatuses")
。它会起作用的。 :)
关于java - 在 CriteriaQuery 中使用 @ElementCollection(或查询 @ElementCollection 的内容),我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/3892851/