spring – JPA2 Criteria-API:select … in(select from where)
作者:互联网
我有以下数据库模型:
A
aId
AB
aId
bId
B
bId
status
在Spring数据规范中,我想在B.status为’X’时返回A的实例.
JPQL代码如下:
select a from A a where a in
(select ab.id.a from AB ab where ab.id.b.status= :status)
这些是模型类:
@Entity
public class A {
private Long aId;
@OneToMany(fetch = FetchType.EAGER, cascade = CascadeType.ALL, mappedBy = "id.a")
private Set<AB> ab;
}
@Entity
public class B {
private Long bId;
private String Status;
@OneToMany(fetch = FetchType.EAGER, cascade = CascadeType.ALL, mappedBy = "id.b")
private Set<AB> ab;
}
@Entity
public class AB {
private ABPK id;
}
public class ABPK {
@ManyToOne
@JoinColumn(name="aId")
private A a;
@ManyToOne
@JoinColumn(name="bId")
private B b;
}
如何在春季规范中的JPA标准?
public class ASpecifications {
public static Specification<A> test(final String status) {
return new Specification<Party>() {
@Override
public Predicate toPredicate(Root<A> a, CriteriaQuery<?> query, CriteriaBuilder cb) {
return null;
}
};
}
}
解决方法:
使用Criteria API返回A实例的规范如下:
public class ASpecifications {
public static Specification<A> test(final String status) {
return new Specification<Party>() {
@Override
public Predicate toPredicate(Root<A> a, CriteriaQuery<?> query, CriteriaBuilder cb) {
Subquery<A> sq = query.subquery(A.class);
Root<AB> ab = sq.from(AB.class);
sq.select(ab.get(AB_.id).get(ABPK_.a));
sq.where(cb.equal(ab.get(AB_.id).get(ABPK_.b).get(B_.status), status));
Predicate p = cb.in(a).value(sq);
return cb.and(p);
}
};
}
}
标签:criteria-api,spring,jpa-2-0,specifications 来源: https://codeday.me/bug/20191001/1838298.html