View:

<%@ Page Title="" Language="C#" MasterPageFile="~/Views/Shared/Site.Master" Inherits="System.Web.Mvc.ViewPage<RegistrationViewModel>" %>

 <h2>EStudy Registration</h2>

    <%
        using (Html.BeginForm(new { Action = "Register" }))

        { %>


    <%= Html.ValidationSummary("Registration Errors:") %>

    FirstName: <%= Html.TextBox("FirstName")%> <br />
    <%= Html.ValidationMessage("FirstName","!") %>
    LastName: <%= Html.TextBox("LastName")%> <br />
    MiddleName: <%= Html.TextBox("MiddleName")%>   <br />

    UserName: <%= Html.TextBox("UserName")%> <br />
    Password: <%= Html.Password("Password")%> <br />
    Email: <%= Html.TextBox("Email")%> <br />

    Select Role: <%= Html.DropDownList("SelectedRoleId", Model.Roles) %>

    <input type="submit" value="Register" />

    <% }%>


Controller:

  public class RegistrationController : BaseController
    {
        private IRoleRepository _roleRepository;
        private IUserRepository _userRepository;

        public RegistrationController() {}

        public RegistrationController(IRoleRepository roleRepository, IUserRepository userRepository)
        {
            _roleRepository = roleRepository;
            _userRepository = userRepository;
        }

        public ActionResult Index()
        {
            var roles = _roleRepository.GetAll();

            var viewModel = new RegistrationViewModel()
                                {
                                    Roles = roles != null ? roles.ToSelectList("RoleName","RoleId") : null
                                };

            return View(viewModel);
        }

        public ActionResult Confirm()
        {
            return View("Index");
        }



      public ActionResult Register(RegistrationViewModel registrationViewModel)
        {

            // convert from view model to the model using auto mapper!
            var newUser = new User()
                              {
                                  Active = true,
                                  DateCreated = DateTime.Now,
                                  DateModified = DateTime.Now,
                                  FirstName = registrationViewModel.FirstName,
                                  LastName = registrationViewModel.LastName,
                                  MiddleName = registrationViewModel.MiddleName,
                                  UserName = registrationViewModel.UserName,
                                  Password = registrationViewModel.Password,
                                  Email = registrationViewModel.Email,
                              };

            var role = _roleRepository.GetByName("Student");
            newUser.AddRole(role);

            // add the errors to the modelstate list
            try
            {
                _userRepository.Save(newUser);
            }
            catch(BrokenRuleException brokenRuleException)
            {
                ModelState.Merge(brokenRuleException.BrokenRules.ToModelStateDictionary());
            }

            if (ModelState.IsValid)
                return View("Confirm");

            // add the broken rules
            TempData["ModelState"] = ModelState;
            return View("Index",registrationViewModel); <--- Error is thrown when the View is bind again!
        }
    }


View Model:

 public class RegistrationViewModel
    {
        [Required(ErrorMessage = "FirstName is required!")]
        public string FirstName { get; set; }
        [Required(ErrorMessage = "LastName is required!")]
        public string LastName { get; set; }
        public string MiddleName { get; set; }

        [Required(ErrorMessage = "UserName is required!")]
        public string UserName { get; set; }

        [Required(ErrorMessage = "Password is required!")]
        public string Password { get; set; }


        [Required]
        public string Email { get; set; }

        public int SelectedRoleId { get; set; }

        public SelectList Roles { get; set; }

    }

Thanks!
















THE ERROR IS POINTING TO THE UserName Field.

Source Error:


Line 25:     MiddleName: <%= Html.TextBox("MiddleName")%>   <br />
Line 26:
Line 27:     UserName: <%= Html.TextBox("UserName")%> <br />
Line 28:     Password: <%= Html.Password("Password")%> <br />
Line 29:     Email: <%= Html.TextBox("Email")%> <br />




[NullReferenceException: Object reference not set to an instance of an object.]
   System.Web.Mvc.HtmlHelper.GetModelStateValue(String key, Type destinationType) +60
   System.Web.Mvc.Html.InputExtensions.InputHelper(HtmlHelper htmlHelper, InputType inputType, String name, Object value, Boolean useViewData, Boolean isChecked, Boolean setId, Boolean isExplicitValue, IDictionary`2 htmlAttributes) +521
   System.Web.Mvc.Html.InputExtensions.TextBox(HtmlHelper htmlHelper, String name, Object value, IDictionary`2 htmlAttributes) +34
   System.Web.Mvc.Html.InputExtensions.TextBox(HtmlHelper htmlHelper, String name) +60
   ASP.views_registration_index_aspx.__RenderContent2(HtmlTextWriter __w, Control parameterContainer) in c:\Projects\EStudyVS2008\EStudySoltution\EStudy\EStudy.Web.UI\Views\Registration\Index.aspx:27
   System.Web.UI.Control.RenderChildrenInternal(HtmlTextWriter writer, ICollection children) +256
   System.Web.UI.Control.RenderChildren(HtmlTextWriter writer) +19
   System.Web.UI.Control.Render(HtmlTextWriter writer) +10