c# - Entity Framework 外键(或缺少外键)

Question

所以我一直在倾注这段代码，试图弄清楚这一点......我在 .NET 3.5 SP1 中使用 Entity Framework 1.0 和 ASP.NET MVC 以及 EFPocoAdapter(所以单独的 Poco 类)。

所以我有以下 Controller 之一的代码:

    [AcceptVerbs(HttpVerbs.Post)]
    public ActionResult EditUser(int? id, FormCollection form)
    {
        var user = new User();

        using (var db = new UMSEntities { DeferredLoadingEnabled = false })
        {
            if (id != null)
            {
                user = db.Users.FirstOrDefault(p => p.UserID.Equals((int) id));
                db.LoadProperty(user, p => p.UserProfiles);
                db.LoadProperty(user, p => p.UserCompanyProfile);
            }
            else
            {
                user.UserGuid = Guid.NewGuid();
                user.DateCreated = DateTime.Now;
                user.DateLastActivity = DateTime.Now;
                user.DateModified = DateTime.Now;
                user.Password = "demo";
                user.Version = 0;
                user.SecretAnswer = "";
                user.SecretQuestion = "";
                user.IsApproved = true;
                user.IsActive = true;

                user.UserProfiles = new UserProfile();
                user.UserCompanyProfile = new UserCompanyProfile
                      {
                          EmployeeID = "",
                          HireDate = DateTime.Now,
                          Title = "",
                          UserCode = "",
                          Company = db.Companies.First(p => p.CompanyID == 8)
                      };

                db.Users.InsertOnSaveChanges(user);

            }

            TryUpdateModel(user);

            db.SaveChanges();
        }

编辑现有用户非常有效(注意 id != null)。但是，它是添加新用户的代码部分。它一直有效，直到我到达将 UserCompanyProfile 添加到用户对象的代码部分。如果我将这段代码注释掉，它就可以正常工作。当我尝试通过查询数据库将公司附加到 UserCompanyProfile 时出现问题——我收到此错误。

Entities in 'UMSEntities.UserCompanyProfiles' participate in the 'FK__UserCompa__Compa__25869641' relationship. 0 related 'Companies' were found. 1 'Companies' is expected.

顺便说一句，它实际上返回一个公司对象(它是 PocoProxies.CompanyProxy 类型)。如果有任何帮助，我们将不胜感激!

Answer 1

所以我想通了，哦，天哪，这花了我很长时间……也很明显。我没有查询公司并通过 UserCompanyProfile 关联它，而是需要以相反的方式关联它:

                // ...
                user.UserProfiles = new UserProfile();
                user.UserCompanyProfile = new UserCompanyProfile
                      {
                          EmployeeID = "",
                          HireDate = DateTime.Now,
                          Title = "",
                          UserCode = ""
                      };

                var company = db.Companies.First(p => p.CompanyID.Equals(16));
                company.UserCompanyProfile.Add(user.UserCompanyProfile);

                db.Users.InsertOnSaveChanges(user);
                // ...

希望这对其他人有帮助!