该类型参数的方法“System.Linq.Queryable.SelectMany System.Linq.IQueryable [英] The type arguments for method 'System.Linq.Queryable.SelectMany System.Linq.IQueryable

问题描述

在编辑我的仓库类错误弹出

  VAR applicantList =（来自于context.Profiles
                             加入context.APPLICANTs应用
                                在a.PROFILE_ID等于app.Profile_id成加盟
                              从joined.DefaultIfEmpty（）Ĵ//排序依据（V =＆GT; v.APPLICANT_ID）。
                             选择j可//＆LT;  - 这是申请者键入
                               ）。取（1000）;   applicantdata = applicantList
                  .SelectMany（C =＆GT; c.APPLICANTs）//这一行加
                  。.AsQueryable（）的OrderBy（V =＆GT; v.APPLICANT_ID）.ToList（）;                如果（applicantdata.Any（））
                {
                    Cache.Set（申请人，applicantdata，30）;
                }
            }
            返回applicantdata;
 

林具有

异常

  .SelectMany（C =＆GT; c.APPLICANTs）//这一行加
 

说：

  

有关方法的类型参数'System.Linq.Queryable.SelectMany（System.Linq.IQueryable，System.Linq.Ex pressions.Ex pression >>）不能从使用推断。请尝试显式指定类型参数

解决方案

接受的SelectMany对象的集合，每个人都有一个内置集合属性。

您的第一个语句选择的申请收集和运行在其上的SelectMany似乎没有意义。

结帐这些链接来了解更好的SelectMany

http://msdn.microsoft.com/en-us/library/ bb534336.aspx 结果
差异之间的选择和的SelectMany

While editing my Repository class an Error pops out

 var applicantList = (from a in context.Profiles
                             join app in context.APPLICANTs
                                on a.PROFILE_ID equals app.Profile_id into joined
                              from j in joined.DefaultIfEmpty()//.OrderBy(v => v.APPLICANT_ID)
                             select j //<--  this is APPLICANTs type
                               ).Take(1000);

   applicantdata = applicantList
                  .SelectMany(c => c.APPLICANTs) //this line added
                  .AsQueryable().OrderBy(v => v.APPLICANT_ID).ToList();

                if (applicantdata.Any())
                {
                    Cache.Set("applicants", applicantdata, 30);
                }
            }
            return applicantdata;

Im having an exception at

.SelectMany(c => c.APPLICANTs) //this line added

saying that :

The type arguments for method 'System.Linq.Queryable.SelectMany(System.Linq.IQueryable, System.Linq.Expressions.Expression>>)' cannot be inferred from the usage. Try specifying the type arguments explicitly

解决方案

SelectMany accepts a collection of object which each of them have a collection property inside.

You selected APPLICANTs collection at the first statement and running a SelectMany on it doesn't seem to be meaningful.

Checkout these links to understand the SelectMany better.

http://msdn.microsoft.com/en-us/library/bb534336.aspx
Difference Between Select and SelectMany

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