Question

我正在尝试使用CriteriaBuilder过滤相关的Child-Entities但是没有得到它。我拥有的实体是：

@Entity
public class Parent {
    @ManyToOne
    private Car car;
    @OneToMany
    private List<Child> children;
}

@Entity
public class Child {
   private Long value;
}

@Entity
public class Car {
    private Long id;
}

我想根据值过滤孩子，即我不想得到所有孩子，但那些值在值列表中。

我试过这样：

@Override
public List<Parent> loadParents(final long carId, final List<ParentType> types, final List<Long> values) {

    final CriteriaBuilder criteriaBuilder = em.getCriteriaBuilder();

    final CriteriaQuery<Parent> select = criteriaBuilder.createQuery(Parent.class);

    final Root<Parent> from = select.from(Parent.class);

    final List<Predicate> predicates = new ArrayList<>();

    predicates.add(criteriaBuilder.equal(from.get("car").get("id"), carId));

    if (!CollectionUtils.isEmpty(types)) {
        predicates.add(from.get("type").in(types));
    }

    if (!CollectionUtils.isEmpty(values)) {
        final ListJoin<Parent, Child> join = from.join(em.getMetamodel().entity(Parent.class).getList("children", Child.class));
        final Predicate predicate = join.get(em.getMetamodel().entity(Child.class).getDeclaredSingularAttribute("value", Long.class)).in(values);
        predicates.add(predicate);
    }

    select.where(criteriaBuilder.and(predicates.toArray(new Predicate[predicates.size()])));

    final List<Parent> result = em.createQuery(select).getResultList();

    return result;
}

但我没有得到我想要的结果。删除

    if (!CollectionUtils.isEmpty(values)) {
        final ListJoin<Parent, Child> join = from.join(em.getMetamodel().entity(Parent.class).getList("children", Child.class));
        final Predicate predicate = join.get(em.getMetamodel().entity(Child.class).getDeclaredSingularAttribute("value", Long.class)).in(values);
        predicates.add(predicate);
    }

我让父母和他们相应的孩子在一起。任何人都可以暗示我做错了吗？

由于

使用CriteriaBuilder过滤OneToMany关系

0 个答案: