EF：更新引用的對象

Question

我有以下情況

public static void UpdateUserinfo(int id, Model model) 
{ 
    using (Entities context = new Entities()) 
    { 
     userinfo userinfo = (from u in context.userinfoes where u.Id == id select u).FirstOrDefault(); 

     userinfo.BirthDate = model.Birthdate; 

     var langauges = (from l in context.languages where model.LanguageIDs.Contains((int)l.LanguageID) select l); 
     foreach (var l in langauges) 
     { 
      userinfo.languages.Add(l); 

     } 

     context.SaveChanges(); 
    } 
} 

當我嘗試那樣做，我得到一個錯誤：

{"There is already an open DataReader associated with this Connection which must be closed first."}

所以基本上我有一個表的語言和我有表userinfo和一個關聯表userlanguages，所以基本上在EF你可以導航userinfo.langauges ...

我的問題我如何正確更新它，我如何添加新的語言到userinfo呢？

或者我應該mabye有類似：

userinfo.languages = languages 

但我不得不放棄ICollection的，但怎麼辦呢？

Answer 1

的問題是在連接字符串中你應該添加MultipleActiveResultSets=true。一旦你添加了這個，你可以即時迭代導航屬性。

Answer 2

使用兩上下文對象，就像這樣：

public static void UpdateUserinfo(int id, Model model) 
{ 
    using (Entities context = new Entities()) 
    using (Entities context2 = new Entities()) 
    { 
     userinfo userinfo = (from u in context.userinfoes where u.Id == id select u).FirstOrDefault(); 

     userinfo.BirthDate = model.Birthdate; 

     var langauges = (from l in context2.languages where model.LanguageIDs.Contains((int)l.LanguageID) select l); 
     foreach (var l in langauges) 
     { 
      userinfo.languages.Add(l); 

     } 

     context.SaveChanges(); 
    } 
}