为什么我的代码在 Entity Framework 中没有更新？

Question

您好，我是 .Net MVC 的新程序员。你觉得我在哪里犯错了吗？我的代码不会更新我的数据。你能帮我解决这个问题吗？

 public class MemberModel
{
    public int UserID { get; set; }
    public string UserName { get; set; }
    public string UserSurname { get; set; }
    public string UserPassword { get; set; }
    public string UserEmail { get; set; }
}

public class UserinfoModel
    {
        public int UserInfoID { get; set; }
        public Nullable<System.DateTime> DateOfBirth { get; set; }
        public string PhoneNumber { get; set; }
        public string Adress { get; set; }
        public byte[] UserImage { get; set; }
        public Nullable<int> fk_GenderID { get; set; }
        public Nullable<int> fk_UserID { get; set; }

        public virtual tbl_Gender tbl_Gender { get; set; }
        public virtual tbl_Member tbl_Member { get; set; }
    }

如果我写 db.tbl_Userinfo.Add(userinfo) ，它会在我的数据库中添加一条新记录。我不明白错误在哪里。

---班级部分--

 public ActionResult Edit()
        {
            var dataSet = Session["Users"] as tbl_Member;
             var member = db.tbl_Userinfo.FirstOrDefault(m => m.fk_UserID == dataSet.UserID);
             var change = new UserinfoModel();
             change.UserInfoID = member.UserInfoID;
             change.Adress = member.Adress;
             change.DateOfBirth = member.DateOfBirth;
             change.PhoneNumber = member.PhoneNumber;
             change.UserImage = member.UserImage;
             change.fk_UserID = member.fk_UserID;
             ViewBag.fk_GenderID = new SelectList(db.tbl_Gender, "GenderID", "Gender");


            return View(change);

        }
        [HttpPost]
        public ActionResult Edit(UserinfoModel Userinfo)
        {
            var userinfo = new tbl_Userinfo();

            userinfo.Adress = Userinfo.Adress;
            userinfo.DateOfBirth = Userinfo.DateOfBirth;
            userinfo.PhoneNumber = Userinfo.PhoneNumber;
            userinfo.UserImage = Userinfo.UserImage;
            userinfo.fk_GenderID = Userinfo.fk_GenderID;
            db.SaveChanges(); /* it does not work.*/
            return RedirectToAction("Show"); /* is it true?
        }


    }

Answer 1

您需要更新附加到数据上下文的行或添加新行。

我将编辑代码包括在内，因为这就是您的控制器操作所说的。如果你想创建一个全新的行，你需要在调用 SaveChanges() 之前添加你的 DbSet 记录。

[HttpPost]
public ActionResult Edit(UserinfoModel Userinfo)
{
    var dataSet = Session["Users"] as tbl_Member;
    var member = db.tbl_Userinfo.FirstOrDefault(m => m.fk_UserID == dataSet.UserID);

    member.Adress = Userinfo.Adress;
    member.DateOfBirth = Userinfo.DateOfBirth;
    member.PhoneNumber = Userinfo.PhoneNumber;
    member.UserImage = Userinfo.UserImage;
    member.fk_GenderID = Userinfo.fk_GenderID;
    db.SaveChanges(); 
    return RedirectToAction("Show");
}