java – 标准JPA 2与3表

我正在尝试创建一个条件,从3个表(关联,更新和细节)中检索一些对象.详细信息参考关联和更新,更新引用了详细信息列表.我的目标是在给定一个关联标识符的情况下,在指定的字段中检索至少具有空值的详细信息的更新列表.在JPQL中很容易做到,但客户端表示这必须用标准编码.

我的JPQL是：

public List<Update> getUpdates(long associateId) {
    TypedQuery<Update> query = em.createQuery("select distinct u from Update u,Detail dt,Associate a "
        + "where dt.update = u and dt.associate = a and a.associateId = :id and "
        + "dt.ack_date is null",Update.class);
    query.setParameter("id",associateId);
    return query.getResultList();
}

我尝试了以下,但它只是返回数据库中的所有更新：

public List<Update> getUpdates(long associateId) {
    CriteriaBuilder builder = em.getCriteriaBuilder();
    CriteriaQuery<Update> query = builder.createQuery(Update.class);

    Root<Update> fromUpdates = query.from(Update.class);
    Root<Associate> fromAssociate = query.from(Associate.class);
    Root<Detail> fromDetail = query.from(Detail.class);

    Join<Detail,Associate> associateJoin = fromDetail.join("associate");
    Join<Detail,Update> updateJoin = fromDetail.join("update");

    TypedQuery<Update> typedQuery = em.createQuery(query

            .select(fromUpdates)
            .where(builder.and(
                    builder.equal(fromAssociate.get("associateId"),associateId),builder.equal(fromDetail.get("associate"),associateJoin),builder.equal(fromDetail.get("update"),updateJoin),builder.isNull(fromDetail.get("ack_date"))
            ))

            .orderBy(builder.asc(fromUpdates.get("updateId")))
            .distinct(true)
    );

    return typedQuery.getResultList();
}

有人可以帮我吗我搜索,但找不到任何与3个实体的例子.

解决方法

Root<Update> fromUpdates = query.from(Update.class);
Join<Update,Detail> details = fromUpdates.join("details");
Join<Detail,Associate> associate = details.join("associate");
List<Predicate> conditions = new ArrayList();
conditions.add(builder.equal(associate.get("associateId"),associateId));
conditions.add(builder.isNull(details.get("ack_date")));

TypedQuery<Update> typedQuery = em.createQuery(query
        .select(fromUpdates)
        .where(conditions.toArray(new Predicate[] {}))
        .orderBy(builder.asc(fromUpdates.get("updateId")))
        .distinct(true)
);

（编辑：安卓应用网）

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