c# – 如何从linq到实体查询获取toTraceString()？

发布时间：2020-12-15 08:32:01 所属栏目：百科来源：网络整理

导读：dynamic traceFile = Environment.GetFolderPath(Environment.SpecialFolder.Desktop) + "EntityFrameworkTrace.log"; var CurrentStock = (from s in DBViews.StockStatus where s.ProductID != 10 orderby s.ProductName select new { s.ProductID,s.Pro

dynamic traceFile =  Environment.GetFolderPath(Environment.SpecialFolder.Desktop) + "EntityFrameworkTrace.log";                
var CurrentStock = (from s in DBViews.StockStatus
                    where s.ProductID != 10
                    orderby s.ProductName
                    select new
                    {
                        s.ProductID,s.ProductName,CurrentStock = s.TotalStocked - s.TotalSold,s.CurrentSellingRate,CashValue = (s.TotalStocked - s.TotalSold) * s.CurrentSellingRate,s.LastStocked,s.LastCostPrice,s.LastQtyStocked
                    }).ToList();

File.AppendAllText(traceFile,CurrentStock.toTraceString());   
return CurrentStock.ToList();

如何从CurrentStock上获取toTraceString()在以下行？它没有得到解决

File.AppendAllText(traceFile,CurrentStock.toTraceString());

解决方法

你不能因为你已经调用了ToList – 它不是Linq-to-Entities查询而只是一个List实例.

试试这个：

var CurrentStock = (from s in DBViews.StockStatus
                    where s.ProductID != 10
                    orderby s.ProductName
                    select new
                    {
                        s.ProductID,s.LastQtyStocked
                    }); // No ToList here!

File.AppendAllText(traceFile,((ObjectQuery)CurrentStock).ToTraceString());   
return CurrentStock.ToList();

顺便说一句.为什么你使用动态而不是字符串？动态类型仅适用于有意义的特殊情况 – 事实并非如此.

（编辑：李大同）

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