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我有以下 Criteria API 查询用于根据多个Subject属性评估给定值。

...
    Expression literal = builder.literal((String) "%" + filterValue + "%");

    // When the globalFilter is deleted it returns ""
    if (!"".equals(filterValue)) {
        // JPQL equivilant: SELECT e FROM Subject e JOIN e.company c JOIN e.contact ct WHERE c.name LIKE :literal OR ct.firstName LIKE :literal ... etc
        List<Predicate> globalPredicate = new ArrayList<>();

        globalPredicate.add(builder.like(subject.get(Subject_.email), literal));
        globalPredicate.add(builder.like(subject.join(Subject_.contact).get(Contact_.firstName), literal));
        globalPredicate.add(builder.like(subject.join(Subject_.contact).get(Contact_.lastName), literal));
        globalPredicate.add(builder.like(subject.join(Subject_.metier).get(Metier_.name), literal));
        globalPredicate.add(builder.like(subject.join(Subject_.company).get(Company_.name), literal));

        predicates.add(builder.or(globalPredicate.toArray(new Predicate[globalPredicate.size()])));
    }
...

这将创建以下查询：

SELECT t1.UID AS a1, t1.EMAIL AS a2, t1.PASSWORD AS a3, t1.VERSION AS a4, t1.COMPANY_ID AS a5, t1.METIER_ID AS a6, t1.ACCOUNT_ID AS a7, t1.CONTACT_ID AS a8 FROM METIER t3, COMPANY t2, SUBJECT t1, CONTACT t0 WHERE (((((t1.EMAIL LIKE ? OR t0.FIRSTNAME LIKE ?) OR t0.LASTNAME LIKE ?) OR t3.NAME LIKE ?) OR (t2.NAME LIKE ? IS NOT NULL)) AND (((t0.ID = t1.CONTACT_ID) AND (t3.ID = t1.METIER_ID)) AND (t2.ID = t1.COMPANY_ID))) LIMIT ?, ?

我遇到的问题是Subject_.companycan 是null. 该查询有效地忽略了所有Subject_.company设置为的条目null。

我需要以某种方式修改此查询，以便null不会自动丢弃这些值。

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1 回答 1

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您需要使用带有 JoinType 参数的 join 方法，并指定 JoinType.LEFT 以便它使用左外连接而不是默认值。 

globalPredicate.add(builder.like(subject.join(Subject_.company, JoinType.LEFT).get(Company_.name), literal));

左外连接将防止 Subject->Company 关系过滤掉空公司的结果。

于 2013-08-14T18:09:37.113 回答