小编mur*_*elK的帖子

我正在尝试转换这个原始的SQL查询:

select product.* from following_relationship
join product on following_relationship.following=product.owner_id
where following_relationship.owner=input 

进入Spring Data规范,我认为到目前为止我的问题是加入这些表.

这是我目前在规范中的转换:

protected Specification<Product> test(final User user){
   return new Specification<Product>() {
       @Override
       public Predicate toPredicate(Root<Product> root, CriteriaQuery<?> query, CriteriaBuilder cb) {
           Join<FollowingRelationship,Product> pfJoin = query.from(FollowingRelationship.class).join("following");
           pfJoin.on(cb.equal(pfJoin.get("following"),"owner"));
           return  query.where(cb.equal(pfJoin.get("following"),user)).getGroupRestriction();

       }
   };
}

我得到了这个例外:

Request processing failed; nested exception is org.springframework.dao.InvalidDataAccessA
piUsageException: org.hibernate.hql.internal.ast.InvalidWithClauseException: with clause can only reference columns in the driving table 

我想补充一点,我是Spring框架的新手,例如这是我春天的第一个应用程序,所以我为新手问题道歉;)

编辑:添加的实体Product,FollowingRelationShip

Entity
@JsonIdentityInfo(generator = ObjectIdGenerators.IntSequenceGenerator.class, property = "json_id_prop")
public class FollowingRelationship extends BaseEntity {

    @ManyToOne(fetch = …

我最近在Joaquim Verques的演讲中听说过Realm for android(也可用于iOS).非常有趣且非常强大的持久数据工具.

我决定在视频之后试一试,研究和阅读文档.

我发现它很容易使用和设置,但我最终陷入了我的项目中间,因为我无法成功地进行多对多关系的查询.

我为这个主题创建了一个小例子.

我的模特:

public class Feed extends RealmObject {

    @PrimaryKey
    private int id;
    private String title;
    private String description;
    private String link;
    private Terms terms;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public String getDescription() {
        return description;
    }

    public void setDescription(String description) {
        this.description = description;
    } …