Asp.Net MVC C# 更新/编辑用户模型状态无效

我有一个简单的问题，我正在更新我的用户，那里的角色和我的 modelstate.isvalid 失败了。所以用户不会在数据库中得到更新。我没有任何 [必需] 没有输入到文本框中，即使我尝试输入所有字段，它仍然失败。不知道为什么。

这是我的数据模型，我用于编辑/更新用户和角色的控制器操作，还有我的视图，其中包含视图内部的所有控件。我真的不知道为什么我的模型状态无效我没有做任何复杂的事情它只是 CRUD 中的一个简单的 U 并且动作控制器没有验证模型。

public class UpdateUserViewModel
    {
        public string UserId { get; set; }
        [Display(Name = "User ID")]
        public string IdShortened { get; set; }
        [Required]
        [EmailAddress]
        [Display(Name = "Email")]
        public string Email { get; set; }
        [Required]
        [Display(Name = "Username")]
        public string UserName { get; set; }
        [Display(Name = "Your Name")]
        public string Name { get; set; }
        [Display(Name = "Phone Number")]
        public string PhoneNumber { get; set; }
        [DataType(DataType.DateTime),
            DisplayFormat(DataFormatString = "{0:dd/MM/yyyy}",
            ApplyFormatInEditMode = true)]
        [Display(Name = "Birthday")]
        public DateTime Birthday { get; set; }
        [Display(Name = "Date Created")]
        public DateTime? DateCreated { get; set; }
        [Required]
        [Display(Name = "User Roles")]
        public string UserRoles { get; set; }
    }
public async Task<ActionResult> EditSuperAdmin(string id)
        {
            if(id == null)
            {
                return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
            }
            var store = new UserStore<ApplicationUser>(context);
            var manager = new UserManager<ApplicationUser>(store);
            var user = await manager.FindByIdAsync(id);
            if(user == null)
            {
                return HttpNotFound();
            }
            var userRoles = await manager.GetRolesAsync(user.Id);

            ViewBag.Roles = new SelectList(
                context.Roles.ToList(), "Name", "Name");
                //new SelectList(context.Roles.Where(u =>
               //!u.Name.Contains("SuperAdmin")).ToList(), "Name", "Name");

            return View(new UpdateUserViewModel()
            {
                UserId = user.Id,
                IdShortened = user.Id.Substring(0, 10),
                Email = user.Email,
                UserName = user.UserName,
                Name = user.Name,
                PhoneNumber = user.PhoneNumber,
                Birthday = user.Birthday,
                DateCreated = user.DateCreated,
                UserRoles = manager.GetRoles(user.Id).FirstOrDefault()
            });
        }
        [HttpPost]
        [ValidateAntiForgeryToken]
        public ActionResult EditSuperAdmin([Bind]UpdateUserViewModel model)
        {
            var store = new UserStore<ApplicationUser>(context);
            var manager = new UserManager<ApplicationUser>(store);

            if (ModelState.IsValid)
            {
                var user = manager.FindById(model.UserId);
                if (user == null)
                {
                    return HttpNotFound();
                }
                user.Email = model.Email;
                user.UserName = model.UserName;
                user.Name = model.Name;
                user.PhoneNumber = model.PhoneNumber;
                user.Birthday = model.Birthday;
                user.DateCreated = Convert.ToDateTime(model.DateCreated);
                var roleResult =
                    manager.AddToRole(user.Id, model.UserRoles);
                if (!roleResult.Succeeded)
                {
                    TempData["ErrorRole"] = "Error adding User Role";
                    return RedirectToAction("Dashboard");
                }
                manager.Update(user);
                context.SaveChanges();                
                TempData["Success"] = "User Updated Successfully";              
                return RedirectToAction("GetAllUsers", "SuperAdmin");
            }
            TempData["Error"] = "User Update Failed";
            return RedirectToAction("Dashboard");
        } @model MVC_TimeSh.Models.UpdateUserViewModel
@{
    ViewData["Title"] = "Update User";
}

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

    <div class="form-horizontal">
        <div class="text-center">
            @if (User.IsInRole("SuperAdmin"))
            {
                <h2>Update Super Administrator</h2>
            }
            else
            {
                <h3>Update | Edit User Account</h3>
            }
        </div>
        <hr />
        @Html.ValidationSummary(true, "", new { @class = "text-danger" })
        @Html.HiddenFor(m => m.UserId)

        <div class="form-group">
            @Html.LabelFor(model => model.IdShortened,
             htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                @Html.EditorFor(model => model.IdShortened, new { htmlAttributes =
                 new { @class = "form-control", @readonly = "readonly" } })
                @Html.ValidationMessageFor(model => model.IdShortened, "",
                 new { @class = "text-danger" })
            </div>
        </div>

        <div class="form-group">
            @Html.LabelFor(model => model.Name,
             htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                @Html.EditorFor(model => model.Name,
                 new { htmlAttributes = new { @class = "form-control" } })
                @Html.ValidationMessageFor(model => model.Name, "",
                 new { @class = "text-danger" })
            </div>
        </div>

        <div class="form-group">
            @Html.LabelFor(model => model.Email,
             htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                @Html.EditorFor(model => model.Email, new { htmlAttributes =
                 new { @class = "form-control" } })
                @Html.ValidationMessageFor(model => model.Email, "",
                 new { @class = "text-danger" })
            </div>
        </div>

        <div class="form-group">
            @Html.LabelFor(model => model.UserName,
             htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                @Html.EditorFor(model => model.UserName,
                 new { htmlAttributes = new { @class = "form-control" } })
                @Html.ValidationMessageFor(model => model.UserName, "",
                 new { @class = "text-danger" })
            </div>
        </div>

        <div class="form-group">
            @Html.LabelFor(model => model.PhoneNumber,
             htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                @Html.EditorFor(model => model.PhoneNumber,
                 new { htmlAttributes = new { @class = "form-control" } })
                @Html.ValidationMessageFor(model => model.PhoneNumber, "",
                 new { @class = "text-danger" })
            </div>
        </div>

        <div class="form-group">
            @Html.LabelFor(model => model.Birthday,
             htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                @Html.EditorFor(model => model.Birthday,
                 new { htmlAttributes = new { @class = "form-control datepicker" } })
                @Html.ValidationMessageFor(model => model.Birthday, "",
                 new { @class = "text-danger" })
            </div>
        </div>

        <div class="form-group">
            @Html.LabelFor(model => model.DateCreated,
             htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                @Html.EditorFor(model => model.DateCreated, new { htmlAttributes =
                 new { @class = "form-control", @readonly = "readonly" } })
                @Html.ValidationMessageFor(model => model.DateCreated, "",
                 new { @class = "text-danger" })
            </div>
        </div>

        <div class="form-group">
            @Html.LabelFor(model => model.UserRoles,
             htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                @Html.DropDownList("UserRoles", (SelectList)ViewBag.Roles, "-- SELECT --")
                @*new { htmlAttributes = new { @class = "form-control" } })*@

                @Html.ValidationMessageFor(model => model.UserRoles, "",
                 new { @class = "text-danger" })
            </div>
        </div>

        <div class="form-group">
            <div class="col-md-offset-2 col-md-10">
                <input type="submit" value="Save" class="btn btn-success" />
            </div>
        </div>
    </div>