modelstate.isvalid false，因为该项始终为null

所以我尝试制作一个asp.net核心2（视觉工作室2017） . 试图为主银行制作一个简单的视图，新建，编辑和删除 . 我已经成功完成了视图并创建了新视图，但现在我被困在编辑部分 . 因此，当用户单击编辑时，我打开新窗口并显示要编辑的详细信息，然后当他们单击保存按钮时，我保存了值（如创建新建时） . 就是这么简单 . 但由于某种原因，用于编辑的modelstate.isvalid总是为false，当我尝试调试时，我发现所有项都返回null（它们都显示在视图上），但主键除外 . 请帮助我做错了：

class ：

public class MsBank
        {
            [Required(ErrorMessage = "Required.")]
            [RegularExpression(@"\b[A-Z0-9]{1,}\b", ErrorMessage = "Must Be Uppercase")]
            public string BankCode { get; set; }

            [Required(ErrorMessage = "Required.")]
            public string BankName { get; set; }

            public string BankBranch { get; set; }

            private SqlConnection con;
            private void connection()
            {
                PrjCommon dbhandle = new PrjCommon();
                con = new SqlConnection(dbhandle.GetSetting());
            }

    public bool AddBank(List smodel)
    {
        connection();
        SqlCommand cmd = new SqlCommand("SaveMsBank", con);
        cmd.CommandType = CommandType.StoredProcedure;

        foreach (var item in smodel) { 
        cmd.Parameters.AddWithValue("@BankCode", item.BankCode);
        cmd.Parameters.AddWithValue("@BankName", item.BankName);
        cmd.Parameters.AddWithValue("@BankBranch", item.BankBranch);
        cmd.Parameters.AddWithValue("@LastUpdatedBy", "Me");
        cmd.Parameters.AddWithValue("@LastUpdatedFromModule", "NET");
        }
        con.Open();
        int i = cmd.ExecuteNonQuery();
        con.Close();

        if (i >= 1)
            return true;
        else
            return false;
    }
}
    }

风景 ：

@model List[MsBank]
    @{
        ViewData["Title"] = "Edit";
    }

    @using (Html.BeginForm())
        {
    @Html.AntiForgeryToken()

    
        
            

            @foreach (var item in Model) {
            
                Code :
                @Html.EditorFor(model => item.BankCode, new { htmlAttributes = new { @class = "form-control" } })
                @Html.ValidationMessageFor(model => item.BankCode, "", new { @class = "text-danger" })
            
            
                Name :
                @Html.EditorFor(model => item.BankName, new { htmlAttributes = new { @class = "form-control" } })
                @Html.ValidationMessageFor(model => item.BankName, "", new { @class = "text-danger" })
            
            
                Branch :
                @Html.EditorFor(model => item.BankBranch, new { htmlAttributes = new { @class = "form-control" } })
                @Html.ValidationMessageFor(model => item.BankBranch, "", new { @class = "text-danger" })
            
            
                
            
            }
        
    
    }
    @ViewBag.Message
    
        @Html.ActionLink("Back to List", "Index")
    

    @section Scripts {
        @{await Html.RenderPartialAsync("_ValidationScriptsPartial");}
    }

和控制器：

public ActionResult Edit(string BankCode)
        {
            MsBank ms = new MsBank();
            ModelState.Clear();
            return View(ms.GetData(BankCode));
        }

        [HttpPost]
        [ValidateAntiForgeryToken]
        public ActionResult Edit(string BankCode,List smodel)
        {
            try
            {
                if (ModelState.IsValid)
                {
                    if (smodel.Count > 0)
                    {
                        MsBank ms = new MsBank();
                        if (ms.AddBank(smodel))
                        {
                            ViewBag.Message = "Bank Edited Successfully";
                            ModelState.Clear();
                        }
                        return RedirectToAction("Index");
                    }
                    else { ViewBag.Message = "Empty Record"; }
                }
                return View(smodel);
            }
            catch (Exception e)
            {
                ViewBag.Message = e.ToString();
                return View(smodel);
            }
        }

所以，为了使它更清楚，上面的modelstate.isvalid返回false（当我发现调试时）因为bankname为null，所以bankbranch也是null