Question

public class News
{
    public virtual int Id { set; get; }
    public virtual string Title { get; set; }
    public virtual string Thumbnail { set; get; }
    public virtual string Image { set; get; }
    public virtual string NewsContent { set; get; }
    public virtual DateTime DateCreated { set; get; }
    public virtual bool Published { set; get; }
    public virtual int UserCreated { set; get; }
    public virtual Category Category { set; get; }
    public virtual DateTime DateUpdated { set; get; }
    public virtual int ViewCount { set; get; }
}

我有这个类，我想查询数据库以获得结果。这是我的疑问：

        foreach (var category in categories)
        {
            var news = newsRepo.Query("from News n where n.Category ="+category);
        }

这是查询方法。

    public IQueryable<T> Query(string query)
    {
        IQueryable<T> queryable;
        using (var session = SessionFactory.OpenSession())
        using (var transaction = session.BeginTransaction())
        {
            var hql = session.CreateQuery(query);
            var list = hql.List<T>();
            queryable = list.AsQueryable();
            transaction.Commit();
        }
        return queryable;
    }

并且它不起作用。

我收到以下错误：

could not execute query
[ select news0_.Id as Id13_, news0_.Title as Title13_, news0_.DateCreated as DateCrea3_13_, news0_.DateUpdated as DateUpda4_13_, news0_.NewsContent as NewsCont5_13_, news0_.Published as Published13_, news0_.UserCreated as UserCrea7_13_, news0_.Image as Image13_, news0_.Thumbnail as Thumbnail13_, news0_.ViewCount as ViewCount13_, news0_.Category_id as Category11_13_ from [News] news0_ where news0_.Category_id=. ]

我该如何解决？

任何想法？

Answer 1

如果你在下面一行代码中加上一个断点，那么你应该看到category变量没有被初始化为你期望的值（应该是一个整数）：

var news = newsRepo.Query("from News n where n.Category ="+category);

除此之外，有几种更好的方法可以促进此查询。一种是像这样使用Session.Get（id）：

var news = Session.Get<News>(1);

你也可以像这样使用NHibernate LINQ提供程序：

var news = Session.Query<News>().SingleOrDefault();

绝对必要时仅使用文字SQL或HQL。

NHibernate查询失败

1 个答案: