C# LINQ to实体无法识别方法'System.LINQ.IQueryable`1

当我执行以下代码时：

IHotelDataAccess _hotelDataAccess= new HotelDataAccess(_entities);
int myVal = (from u in _hotelDataAccess.GetHotelsByCityId(19)
    select u).Count();

myVal按预期返回一个整数值，但是如果我尝试按如下方式返回IQueryable

return (from geoLocation in _entities.ViewGeographyLocation
 where geoLocation.CountryCode == countryCode
 orderby geoLocation.SortOrder, geoLocation.CityName
 select new ContinentModel
 {
  ContinentCode = geoLocation.ContinentCode,
  ContinentName = geoLocation.ContinentName,
  CountryCode = geoLocation.CountryCode,
  CountryName = geoLocation.CountryName,
  CityId = geoLocation.CityId,
  CityName = geoLocation.CityName,
  CityCode = geoLocation.CityName,
  TotalCount = ((from u in _hotelDataAccess.GetHotelsByCityId(19)
   select u).Count())
 });

我得到一个错误：

LINQ to实体无法识别该方法 'System.Linq.IQueryable'1[DestKosher.Model.HotelModel] GetHotelsByCityIdInt32'方法，无法转换此方法 转换为存储表达式

方法hotelDataAccess.GetHotelsByCityId19返回IQueryable。任何想法、帮助或解决方案都将不胜感激。问候,

马丁

更新： 最初设置此查询是为了查看将整数放入函数GetHotelsByCityId是否有效。然而，我最终想做的是：

return (from geoLocation in _entities.ViewGeographyLocation
 where geoLocation.CountryCode == countryCode
 orderby geoLocation.SortOrder, geoLocation.CityName
 select new ContinentModel
 {
  ContinentCode = geoLocation.ContinentCode,
  ContinentName = geoLocation.ContinentName,
  CountryCode = geoLocation.CountryCode,
  CountryName = geoLocation.CountryName,
  CityId = geoLocation.CityId,
  CityName = geoLocation.CityName,
  CityCode = geoLocation.CityName,
  TotalCount = ((from u in _hotelDataAccess.GetHotelsByCityId(geoLocation.CityId)
   select u).Count())
 });

根据设计，需要将整个LINQ查询表达式转换为服务器查询。在翻译查询之前，客户机上只计算查询中不依赖于服务器结果的少数不相关子表达式。不支持没有已知转换的任意方法调用，如本例中的GetHotelsByCityId

你可以这样做

var list = _hotelDataAccess.GetHotelsByCityId(19).ToList();
int myVal = (from u in list
    select u).Count();

而不是在你的查询中使用myval

return (from geoLocation in _entities.ViewGeographyLocation
 where geoLocation.CountryCode == countryCode
 orderby geoLocation.SortOrder, geoLocation.CityName
 select new ContinentModel
 {
  ContinentCode = geoLocation.ContinentCode,
  ContinentName = geoLocation.ContinentName,
  CountryCode = geoLocation.CountryCode,
  CountryName = geoLocation.CountryName,
  CityId = geoLocation.CityId,
  CityName = geoLocation.CityName,
  CityCode = geoLocation.CityName,
  TotalCount = myVal 
 });

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阅读更多细节：

尝试添加名称空间System.Linq，如果您有System.Core程序集引用，还可以检查您的项目引用。

不要忘记升级投票并将答案标记为已接受，如果它适合您……您可以看一下我的更新吗。您好，您能看一下上面的更新吗。非常感谢，Martin你能发布你的_hotelDataAccess.GetHotelsbycity的代码吗？这样我们就可以进行更深入的分析了。这就是我想要的：'return from geoLocation in _entities.ViewGeographyLocation where geoLocation.CountryCode==CountryCode orderby geoLocation.SortOrder，geoLocation.CityName选择新模型{大陆代码=地理位置。大陆代码，大陆名称=地理位置。大陆名称，国家代码=地理位置。国家代码，国家名称=地理位置。国家名称，城市ID=地理位置。城市ID，城市名称=地理位置。城市名称，城市代码=地理位置。城市名称，总计数=来自_hotelDataAccess.gethotelsbycitygeolocation.Cit中的uyId.ToList选择u.Count；}；'