使用NHibernate进行复杂查询

Question

我有这个问题:当我尝试实现Ayende的复杂搜索时,请访问:http: //ayende.com/Blog/archive/2006/12/07/ComplexSearchingQueryingWithNHibernate.aspx ,对象图:人:M:1地址:M :1街道:M:1地点:M:1国家我收到以下错误:NHibernate.QueryException:无法在没有投影的条件下使用子查询.我这样做:

public List<Person> Find() 
{ 
    DetachedCriteria query = DetachedCriteria.For<Person>(); 
    AddAddressQuery(query); 
    return personRepository.Find(query);
} 

private void AddAddressQuery(DetachedCriteria query) 
{ 
     DetachedCriteria addressQuery = null; 
     if (!String.IsNullOrEmpty(SearchParams.HouseNumer)) 
     { 
         addresaQuery = DetachedCriteria.For<Address>(); 
         addresaQuery.Add(Restrictions.Eq("HouseNumer", 
SearchParams.HouseNumer)); 
     } 
     this.AddStreetQuery(ref addressQuery); 
     if (addressQuery != null) 
     { 
         query.CreateCriteria("Address1", 
"address1").Add(Subqueries.Exists(addressQuery)); 
     } 
} 

private void AddStreetQuery(ref DetachedCriteria query) 
{ 
    DetachedCriteria streetQuery = null; 
    if (this.SearchParams.StreetId.HasValue) 
    { 
        streetQuery = DetachedCriteria.For<Street>(); 
        streetQuery .Add( Restrictions.Eq("Id", 
this.SearchParams.StreetId.Value)); 
    } 
    if (streetQuery != null) 
    { 
        query = query ?? Query.CreateCriteria("Address1"); 
        query.CreateCriteria("Street", 
"street").Add(Subqueries.Exists(streetQuery )); 
    } 
} 

我究竟做错了什么？请帮忙

Answer 1

就像错误消息一样 - 您需要为任何子查询设置投影.

您的变量addressQuery(DetachedCriteria)用作子查询,但它没有投影.当转换为SQL时,查询的相关部分将如下所示:

... EXISTS(SELECT FROM Address WHERE HouseNumber = @HouseNumber)

...这是无效的SQL,因为在select子句中没有指定列(也就是投影).

使用SetProjection指定列.