Asp.net mvc LINQ中的c调用方法

我正在使用LINQ，我想通过传递参数调用一个方法，例如checkOpenClose，并让它返回true/false：

我得到以下错误：

LINQ to实体无法识别方法“Boolean checkOpenClose” System.String，System.String，System.String，System.String，System.String， System.String，System.String，System.String，System.String，System.String， System.String，System.String，System.String，System.String，System.String， System.String，System.String'方法，此方法不能为空 翻译成商店表达式

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我做错了什么？

请记住，查询将被转换为sql，因此您的Linq提供程序无法将您的方法调用转换为有效的内容。 如果您确实需要调用该方法，那么我建议调用一个可数扩展方法，如下所示：

   var model=    (from account in _ctx.Account
                  where (...)
                  select account)
                 .AsEnumerable()
                 .Select(account=> new DetailVM
                                   {
                                      Id = account.Id,
                                      Name = account.CompanyName,
                                      OpenNow = checkOpenClose(account.MonOpen, account.MonClosed,
                                                               account.TueOpen, account.TueClosed,
                                                               account.WedOpen, account.WedClosed,
                                                               account.ThuOpen, account.ThuClosed,
                                                               account.FriOpen, account.FriClosed,
                                                               account.SatOpen, account.SatClosed,
                                                               account.SunOpen, account.SunClosed)


                                    })
                .Tolist();

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这将允许您使用Linq执行所需的投影到对象

您的布尔方法中有没有SQL对应的表达式…这已经充实了很多次，请参见

或

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正如我看到的，您正在使用实体框架datacontext，它将linq语句转换为sql脚本，因此当您使用方法时，它无法将其转换为sql。 试试这个

var model= (from account in _ctx.Account
                      where (...)
                      select new {
                          Id = account.Id,
                          Name = account.CompanyName,
                          MO = account.MonOpen, 
                          MC = account.MonClosed,
                          TUO = account.TueOpen, 
                          TUC = account.TueClosed,
                          WO = account.WedOpen,
                          WC = account.WedClosed,
                          THO = account.ThuOpen, 
                          THC = account.ThuClosed,
                          FO = account.FriOpen,
                          FC = account.FriClosed,
                          SO = account.SatOpen,
                          SC = account.SatClosed,
                          SUO = account.SunOpen,
                          SUC = account.SunClosed

                          }).Tolist().select(m=> new DetailVM {

                        Id = account.Id,
                        Name = account.CompanyName,
                        OpenNow = checkOpenClose(MO,MC,TUO,TUC,WO,WC,THO,THC,FO,FC,SO,SC,SUO,SUC)

            }).ToList();

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我试过你的方法，它不承认帐户，这工作！非常感谢。当使用.AsEnumerable时，它执行_ctx.account中的DB from帐户，其中。。。选择account，然后选择select…..ToList从内存中获取值？试着去理解.AsEnumerable做什么以及什么时候应该使用它。如果我错了，请纠正我。在您的数据库中执行一个可数呼叫之前是什么情况。ToList和AsEnumerable之间的主要区别在于AsEnumerable保持不变。有关您的问题的更多信息，请参阅

var model= (from account in _ctx.Account
                      where (...)
                      select new {
                          Id = account.Id,
                          Name = account.CompanyName,
                          MO = account.MonOpen, 
                          MC = account.MonClosed,
                          TUO = account.TueOpen, 
                          TUC = account.TueClosed,
                          WO = account.WedOpen,
                          WC = account.WedClosed,
                          THO = account.ThuOpen, 
                          THC = account.ThuClosed,
                          FO = account.FriOpen,
                          FC = account.FriClosed,
                          SO = account.SatOpen,
                          SC = account.SatClosed,
                          SUO = account.SunOpen,
                          SUC = account.SunClosed

                          }).Tolist().select(m=> new DetailVM {

                        Id = account.Id,
                        Name = account.CompanyName,
                        OpenNow = checkOpenClose(MO,MC,TUO,TUC,WO,WC,THO,THC,FO,FC,SO,SC,SUO,SUC)

            }).ToList();