不能附加已經存在

Question

我試圖通過LINQ到更新代碼的實體，但我得到這個錯誤：

Cannot attach an entity that already exists.

C＃代碼是在這裏：

var con = (from c in cmsContentTable where c.ContentName == contentId 
      select c).FirstOrDefault(); 
cmsContentTable.Attach(con); 
con.ContentData = "New Value"; 
cmsContentTable.Context.SubmitChanges(); 

Answer 1

你不需要附加實體，它已經屬於上下文。

var con = (from c in cmsContentTable where c.ContentName == contentId select c).FirstOrDefault(); 
con.ContentData = "New Value"; 
cmsContentTable.Context.SubmitChanges();