使用实体密钥伪造外键更新

在里面 Alex James' Entity Framework tips articles how to fake foreign key properties . 这似乎正是我所需要的,但无论出于什么原因,我似乎无法在更新时完成它。我的控制器的更新部分中有以下内容:

[AcceptVerbs(HttpVerbs.Post)]
    public ActionResult Edit(candidates candidateToEdit)
    {
        string EduIDValue = candidateToEdit.education.ID.ToString();

        if (!ModelState.IsValid)
            return View();

        try
        {
            var originalCandidate = (from c
                                            in model.candidates
                                            where c.ID == candidateToEdit.ID select c).FirstOrDefault();

            //attempting it here
            originalCandidate.educationReference.EntityKey = new System.Data.EntityKey("model.education", "ID", candidateToEdit.education.ID);

            model.ApplyPropertyChanges(originalCandidate.EntityKey.EntitySetName, candidateToEdit);                
            model.SaveChanges();
            return RedirectToAction("Index");
        }
        catch(Exception e)
        {
            Response.Write("Education ID Value " + EduIDValue + "<br /><br />Error: <br /><br />" + e);
            return null;                
            //return View();
        }
    }

这样做失败,并会产生以下结果:

System.ArgumentException:元数据集合中不存在标识为“model”的成员。参数名称:System.Data.Metadata.Edm.MetadataCollection处的标识 1.GetValue(String identity, Boolean ignoreCase) at System.Data.Metadata.Edm.ReadOnlyMetadataCollection 1.System.Data.Metadata.Edm.ItemCollection.GetEntityContainer(字符串名称,布尔ignoreCase)处System.Data.Metadata.Edm.ItemCollection.GetEntityContainer(字符串名称,布尔ignoreCase)处System.Data.Metadata.Edm.MetadataWorkspace.GetEntityContainer(字符串名称,数据空间数据空间)位于System.Data.Objects.DataClasses.EntityReference.set\u EntityKey(EntityKey值)处的System.Data.EntityKey.GetEntitySet(MetadataWorkspace MetadataWorkspace)处位于System.Data.Objects.DataClasses.EntityReference.set\u EntityKey(EntityKey值)处位于InternicshipTest.Controllers.CandidatesController.Edit(CandidatesCandidatesToEdit)在C:\Documents and Settings\graham\My Documents\Visual Studio 2008\Projects\InternishipTest\InternishipTest\Controllers\CandidatesController.cs中:第84行

这对我来说毫无意义,model绝对是EntitySet的名称。