Question

当我尝试执行下一个HQL查询时，我得到下一个错误：

org.hibernate.hql.internal.ast.QuerySyntaxException：无法找到类[package.CountItemLike]上的适当构造函数[SELECT NEW package.CountItemLike（ll.itemId，COUNT（ll.itemId））FROM package.ItemLike AS ll GROUP BY ll.itemId]

在我的DAO课程中

@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

使用聚合函数count时，返回值为Long。这就是适用的构造函数的原因：

  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ItemLike.itemId和int之间还存在类型不匹配，但是从给定的代码中看不到。

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

1 个答案: