CriteriaBuilder：使用 ON 子句加入一对多

Question

假设您有以下 OneToMany 关系：School->Student->ScientificWork。现在您想要 select 所有拥有姓名为 'John' 且他的科学工作名为 'Black Holes' 的学校。

我是这样做的，但出于某种原因，它会返回所有可能的学校。

public static Specification<School> spec() {
    return (root, query, cb) -> {
        final SetJoin<School, Student> studs = root.joinSet("students", JoinType.LEFT);
        final SetJoin<Student, ScientificWork> works = root.joinSet("works", JoinType.LEFT);
        return cb.and(
                cb.equal(studs.get(Student_.name), 'John'),
                cb.equal(nodes.get(ScientificWork_.name), 'Black Holes')
        );
    };
}

更新

找到 this answer 后，我尝试了以下方法，但结果相同（它 returns 我所有的学校而不是一个）：

public static Specification<School> spec() {
    return (root, query, cb) -> {
        final SetJoin<School, Student> studs = root.joinSet("students", JoinType.LEFT);
        studs.on(cb.equal(studs.get(Student_.name), 'John'));
        final SetJoin<Student, ScientificWork> works = root.joinSet("works", JoinType.LEFT);          
        return cb.equal(nodes.get(ScientificWork_.name), 'Black Holes');
    };
}

Answer 1

public static Specification<School> spec() {
return (root, query, cb) -> {
    final Join<School, Student> studs = root.join("students", JoinType.LEFT);
    studs.on(cb.equal(studs.get(Student_.name), "John"));
    final Join<Student, ScientificWork> works = studs.join("works", JoinType.LEFT);          
    return cb.equal(works.get(ScientificWork_.name), "Black Holes");
};

}

我使用 join 而不是 joinSet 并使用 **works**.get(ScientificWork_.name) 而不是 **nodes**.get(ScientificWork_.name)

CriteriaBuilder：使用 ON 子句加入一对多

CriteriaBuilder: join one-to-many with ON clause

hibernate

criteria-api

spring-data

spring-data-jpa

更新