Question

如何在EF 4中获得我的子类的IEnumerable结果。就像，我的基类的ObjectSet也是一个EntitySet ..但对于我的孩子，我无法查询它们.White一些尝试错误我成功读取，更新，创建，删除..但不查询（或列出）我的子类..

我这样读：

    public Member GetMember(Guid id)
    {
        try
        {
            using (EntitiesContainer db = new EntitiesContainer())
            {
                return db.Resources.SingleOrDefault(x => x.Id == id) as Member;
            }
        }
        catch (Exception ex)
        {
            Log entry = new Log();
            entry.ClassName = GetType().Name;
            entry.Message = ex.Message;
            entry.MethodName = System.Reflection.MethodBase.GetCurrentMethod().Name;
            entry.StackTrace = ex.StackTrace;
            _logger.Log(entry, SeverityEnum.Critical);
        }

        return new Member();
    }

我这样创作：

    public Member CreateMember(Member member, string userName)
    {
        try
        {
            using (EntitiesContainer db = new EntitiesContainer())
            {
                member.Id = (Guid)_userService.GetUser(userName).ProviderUserKey;

                db.Resources.AddObject(member);

                db.SaveChanges();
            }
        }
        catch (Exception ex)
        {
            Log entry = new Log();
            entry.ClassName = GetType().Name;
            entry.Message = ex.Message;
            entry.MethodName = System.Reflection.MethodBase.GetCurrentMethod().Name;
            entry.StackTrace = ex.StackTrace;
            _logger.Log(entry, SeverityEnum.Critical);
        }

        return member;
    }

我这样更新：

    public Member UpdateMember(Member member)
    {
        try
        {
            using (EntitiesContainer db = new EntitiesContainer())
            {
                db.Resources.Attach(GetMember(member.Id));

                db.Resources.ApplyCurrentValues(member);

                db.SaveChanges();
            }
        }
        catch (Exception ex)
        {
            Log entry = new Log();
            entry.ClassName = GetType().Name;
            entry.Message = ex.Message;
            entry.MethodName = System.Reflection.MethodBase.GetCurrentMethod().Name;
            entry.StackTrace = ex.StackTrace;
            _logger.Log(entry, SeverityEnum.Critical);
        }

        return member;
    }

等等......

但是对于列表或查询我的Members Collection或ObjectSet ......我无法做到这一点。

我尝试了类似的东西..但是它返回null或者施法异常。

   public IEnumerable<Member> GetAll()
   {
       try
       {
           using (EntitiesContainer db = new EntitiesContainer())
           {
               var test = db.Resources.ToList() as IList<Member>;

               // OR

               var test = db.Resources as IEnumerable<Member>;

               // OR

               var test = db.Resources.Cast<Member>();

               // OR

               var test = db.Resources.AsEnumerable<Member>();    

               return test;
           }
       }
       catch (System.Exception ex)
       {
           Log entry = new Log();
           entry.ClassName = GetType().Name;
           entry.Message = ex.Message;
           entry.MethodName = System.Reflection.MethodBase.GetCurrentMethod().Name;
           entry.StackTrace = ex.StackTrace;
           _logger.Log(entry, SeverityEnum.Critical);
       }

       return null;
   }

我也尝试为我的会员创建一个ObjectSet，但是他们告诉我，我没有任何这个ObjectSet的EntitySet ..它的逻辑正确..

但是我在调试中看到我的会员有一个DynamicProxies的实例..这个属性是正确的，具有良好的价值..但我不知道如何达到它..我可以相信EF团队他们没有想一想......我在网上到处搜索..没有成功..我需要专家:)！

非常感谢你的时间！我很感激！

Cordialy，朱利安。

Answer 1

EntitiesContainer db = new EntitiesContainer();
var members = db.Resources.OfType<Member>();

EF 4继承了如何查询我的子类的类

1 个答案: