问MVC ModelState IsValid报告为true时应为false

EN

using System.ComponentModel.DataAnnotations;

namespace MyWebApp.Models
{
    public class ApplicationUser
    {
        [Display(Prompt = "Your Name", Name = "Contact Name"), Required(), StringLength(255, MinimumLength = 3, ErrorMessage = "Please enter a valid contact")]
        public string ContactName { get; set; }
        [Display(Name = "Username", Prompt = "Login As"), Required(), StringLength(255, MinimumLength = 3, ErrorMessage = "Your username must be at least 3 characters")]
        public string UserName { get; set; }
    }

    public class Account
    {
        [Display(Name = "Account Type", Prompt = "Account Type"), Required()]
        public int AccountType { get; set; }
        [Display(Name = "Organisation Name", Prompt = "Name of Organisation"), StringLength(255)]
        public string OrganisationName { get; set; }
    }

    public class RegisterViewModel
    {
        public ApplicationUser ApplicationUser { get; set; }
        public Account Account { get; set; }

        public RegisterViewModel()
        {
            ApplicationUser = new ApplicationUser();
            Account = new Account();
        }

        [Display(Name = "Password", Prompt = "Password"), Required(), DataType(DataType.Password), StringLength(255, MinimumLength = 5, ErrorMessage = "The password must be at least 7 characters")]
        public string Password { get; set; }

        [Display(Name = "Confirm Password", Prompt = "Confirm Password"), DataType(DataType.Password), Compare("Password", ErrorMessage = "Your confirmation doesn't match...")]
        public string PasswordConfirmation { get; set; }
    }
}

using System.Web.Mvc;
using MyWebApp.Models;

namespace MyWebApp.Controllers
{
    [Authorize]
    public class AccountController : Controller
    {
        // GET: /Account/
        [AllowAnonymous]
        public ActionResult Register()
        {
            RegisterViewModel mdl = new RegisterViewModel();
            return View(mdl);
        }

        [HttpPost]
        [AllowAnonymous]
        public ActionResult Register([Bind(Include = "Account.AccountType, ApplicationUser.ContactName, ApplicationUser.UserName, Password, Account.OrganisationName, Account.OrganisationRegistrationNumber, Account.AddressLine1, Account.AddressLine2, Account.AddressLine3, Account.City, Account.County, Account.Postcode, ApplicationUser.Email, ApplicationUser.PhoneNumber, PasswordConfirmation")]RegisterViewModel model)
        {
            if (ModelState.IsValid)
            {
                var user = model.ApplicationUser;
                var associatedAccount = model.Account;

                var u1 = Request.Form["ApplicationUser.UserName"];
                if (u1 == user.UserName)
                {
                    // we got it
                    ViewBag.Message = "We got it";
                }
                else
                {
                    // no we didn't
                    ViewBag.Message = "We failed!";
                }
                return View(model);
            }

            // If we got this far, something failed, redisplay form
            return View(model);
        }
    }
}

@using MyWebApp.Models
@model MyWebApp.Models.RegisterViewModel

@{
    ViewBag.Title = "Register User";
}

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

    <div class="form-horizontal">
        <h4>New Account</h4>
        <hr />
        <p>@ViewBag.Message</p>
        @Html.ValidationSummary(true)
        <div class="col-md-6">
            <div class="form-group">
                @Html.LabelFor(model => model.ApplicationUser.ContactName, new { @class = "control-label col-md-5" })
                <div class="col-md-7">
                    @Html.EditorFor(model => model.ApplicationUser.ContactName, new { @class = "form-control" })
                    @Html.ValidationMessageFor(model => model.ApplicationUser.ContactName)
                </div>
            </div>
            <div class="form-group">
                @Html.LabelFor(model => model.ApplicationUser.UserName, new { @class = "control-label col-md-5" })
                <div class="col-md-7">
                    @Html.EditorFor(model => model.ApplicationUser.UserName, new { @class = "form-control" })
                    @Html.ValidationMessageFor(model => model.ApplicationUser.UserName)
                </div>
            </div>
            <div class="form-group">
                @Html.LabelFor(model => model.Password, new { @class = "control-label col-md-5" })
                <div class="col-md-7">
                    @Html.EditorFor(model => model.Password, new { @class = "form-control" })
                    @Html.ValidationMessageFor(model => model.Password)
                </div>
            </div>
            <div class="form-group">
                @Html.LabelFor(model => model.PasswordConfirmation, new { @class = "control-label col-md-5" })
                <div class="col-md-7">
                    @Html.EditorFor(model => model.PasswordConfirmation, new { @class = "form-control" })
                    @Html.ValidationMessageFor(model => model.PasswordConfirmation)
                </div>
            </div>
        </div>
        <div class="col-md-6">
            <div class="org-info">
                <div class="form-group">
                    @Html.LabelFor(model => model.Account.OrganisationName, new { @class = "control-label col-md-5" })
                    <div class="col-md-7">
                        @Html.EditorFor(model => model.Account.OrganisationName, new { @class = "form-control" })
                        @Html.ValidationMessageFor(model => model.Account.OrganisationName)
                    </div>
                </div>
            </div>
            <hr />
            <div class="form-group">
                <div class="col-md-8"></div>
                <div class="col-md-4">
                    <input type="submit" value="Sign Up" class="btn btn-default form-control" />
                </div>
            </div>
        </div>
    </div>
}

Request.Form["ApplicationUser.UserName"]