JPA Criteria API - 子类上带有字段的条件

我有一个名为Issue和实体称为UserIssue. UserIssue延伸Issue.

@Inheritance(strategy = InheritanceType.JOINED)
@Entity(name = "ISSUE")
public class Issue extends VersionedSequenceIdEntity {
... all fields
}

@Entity(name = "USER_ISSUE")
public class UserIssue extends Issue {

    ...

    @Enumerated(EnumType.STRING)
    @Column(name = "CATEGORY", nullable = false)
    private IssueCategory category;

    ...
}

我需要做例如像这样的东西：

Predicate predicate= root.get("category").in(IssueCategory.CATEGORY_1, IssueCategory.CATEGORY_2);

问题是 root 是实例Root<Issue>但“类别”字段是在子类上定义的UserIssue所以这行代码显然不起作用。

有没有办法构建一个谓词来为子类字段创建 where 条件？我只有一个实例Root<Issue>, CriteriaQuery and CriteriaBuilder.

谢谢你， 卢卡斯

    CriteriaBuilder cb = em.getCriteriaBuilder();
    CriteriaQuery<Issue> issueQuery = cb.createQuery(Issue.class);
    Root<Issue> issueRoot = issueQuery.from(Issue.class);

    Subquery<UserIssue> subQuery = issueQuery.subquery(UserIssue.class);
    Root<UserIssue> userIssueRoot = subQuery.from(UserIssue.class);

    Predicate predicate= userIssueRoot.get("category")
          .in(IssueCategory.CATEGORY_1, IssueCategory.CATEGORY_2);
    subQuery.select(userIssueRoot).where(predicate);

    issueQuery.select(issueRoot).where(issueRoot.get("id").in(subQuery));
    em.createQuery(issueQuery).getResultList();