带有 ElementCollection 的 JPA 标准

Question

我有这样的事情：

@Entity
public class Person {

    @ElementCollection
    private List<String> emails;
    ...
}

如何将以下 JPQL 转换为条件查询：

select p from Person p
where exists (
    select 1 
    from p.emails e
    where e like :email
)

Answer 1

If you don't really need the power of LIKE and an exact match is enough you can check if emails contains email.

CriteriaBuilder builder = entityManager.getCriteriaBuilder();
CriteriaQuery<Person> criteria = builder.createQuery(Person.class);
Root<Person> p = criteria.from(Person.class);
criteria.select(p);


Expression<List<String>> emails = p.get(Person_.emails);
criteria.where(builder.isMember("[email address]", emails));


TypedQuery<Person> tq = entityManager.createQuery(criteria);
List<Person> persons = tq.getResultList();

请注意，这p.get(Person_.emails)需要类的静态元模型Person。如果你没有那个，你可以以p.get("emails")类型安全为代价替换那个部分。

如果您确实需要执行LIKE，则必须加入集合。

Join<Person, String> emailJoin = p.join(Person_.emails);
criteria.where(builder.like(emailJoin, "[email address]"));
criteria.distinct(true);