hibernate - JPQL 中的 HQL 'with' 子句

Question

来自 Hibernate 3.6 文档:

You may supply extra join conditions using the HQL with keyword.

from Cat as cat
left join cat.kittens as kitten
    with kitten.bodyWeight > 10.0

此 with子句允许对 JOIN 条件(ON 子句)添加限制。 JPQL 中有这样的东西吗？

当我运行以下 JPQL 时:

select c from ContainerDef c left join fetch c.displayState ds where c.id = 1 and ds.user.id = 2

生成以下 SQL:

select
        ...
    from
        CONTAINER_DEF containerd0_ 
    left outer join
        USER_CONTAINERDEF displaysta1_ 
            on containerd0_.CONTAINERDEF_ID=displaysta1_.CONTAINERDEF_ID 
    where
        containerd0_.CONTAINERDEF_ID=? 
        and displaysta1_.AUTHUSER_ID=?

真正应该生成的是:

select
        ...
    from
        CONTAINER_DEF containerd0_ 
    left outer join
        USER_CONTAINERDEF displaysta1_ 
            on containerd0_.CONTAINERDEF_ID=displaysta1_.CONTAINERDEF_ID 
            and displaysta1_.AUTHUSER_ID=?
    where
        containerd0_.CONTAINERDEF_ID=? 

我确定我缺少 HQL 的正确 JPQL 子句 with .

Answer 1

但是您可以使用 Criteria API 来实现

    Criteria crit = session.createCriteria(Cat.class);
    crit.createAlias("kittens", "kitten", 
        Criteria.LEFT_JOIN, Restrictions.gt("weight", 10.0);

    List<Cat> catsWithFatKittens = crit.list(); 

这是 Criteria.createAlias() 几乎没有记录的签名以 Restriction 对象作为第四个参数。它工作得非常好，值得学习 Criteria API 来获得该功能。