我确定有人已经看到了这一点：无法删除未附加的实体。与LINQ [英] I'm sure someone has seen this: Cannot remove an entity that has not been attached. with LINQ

问题描述

我正在使用LINQ的情况如下：
我有一种查询表并使用以下代码返回一条记录的方法

The scenario I am using LINQ is as follows: I have a method that queries a table and returns one record using the following code

private L2SQLData.PatientFile getpatfile(long id)
{
   var db = new HMSDataContext();
   var patfile = 
   (from f in db.PatientFiles.Where(f=> f.Id == id) select   f).FirstOrDefault() ;

   return patfile;
}

然后另一个代码调用上面的方法并获取返回的对象/记录。然后从同一表中将其删除，如下所示：

Then another code calls the method above and takes object/record that was returned. Then deletes it from the same table as follows:

L2SQLData.PatientFile patfile = getpatfile(long.Parse(id));

var db = new HMSDataContext();
db.PatientFiles.DeleteOnSubmit(patfile);
db.SubmitChanges();

在运行它时，VS2010会发出错误消息：无法删除未附加的实体。我究竟做错了什么？有人吗？

On running it, VS2010 screams with the error: Cannot remove an entity that has not been attached. What am I doing wrong? Anyone?

推荐答案

尝试 db.PatientFiles.Attach（patfile）还是尝试仅使用一个全局 HMSDataContext

Try db.PatientFiles.Attach(patfile) or try using only one globaly HMSDataContext

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