hibernate - QuerySyntaxException 在 Hibernate 中定位适当的构造函数

Question

当我尝试执行下一个 HQL 查询时，出现下一个错误:

org.hibernate.hql.internal.ast.QuerySyntaxException: Unable to locate appropriate constructor on class [package.CountItemLike] [SELECT NEW package.CountItemLike(ll.itemId, COUNT(ll.itemId)) FROM package.ItemLike AS ll GROUP BY ll.itemId]

在我的 DAO 类中

@Override
public List<CountItemLike> countItemLikes() {

    String hql = "SELECT NEW package.CountItemLike"
            + "(ll.itemId, COUNT(ll.itemId)) "
            + "FROM ItemLike AS ll "
            + "GROUP BY ll.itemId";

    Query query = this.getCurrentSession().createQuery(hql); // ERROR IS HERE

    return (List<CountItemLike>) query.list();
}

POJO

public class CountItemLike {

    private int itemId;
    private int likes;

    public CountItemLike(int itemId, int likes){

        this.itemId = itemId;
        this.likes = likes;        
    }

    public int getItemId() {
        return itemId;
    }

        public int getLikes() {
        return likes;
    }   

}

Answer 1

当使用聚合函数count 时，返回值为Long。这就是为什么适用的构造函数是:

  public CountItemLike(int itemId, Long likes){
        this.itemId = itemId;
        this.likes = likes.intValue();        
  }

或:

  public CountItemLike(int itemId, long likes){
        this.itemId = itemId;
        this.likes = (int) likes;        
  }

也许在 ItemLike.itemId 和 int 之间还有类型不匹配，但是从给定的代码中看不到这一点。