如何添加新属性和扩展ApplicationUser类

这是我在这一行的AccountController中得到的错误

IEnumerable<RegisterViewModel> roles = db.Roles.OrderBy(u => u.Name);

不能隐式转换类型"System.Linq.IOrderedQueryable"来"System.Collections.Generic.IEnumerable"。存在显式转换(您是否缺少强制类型转换?)

可以有人谁是MVC专家指向我正确的方向，如何做到这一点?在未来，我将修改我的ApplicationUser类和这个RegisterViewModel来添加更多的变量，例如:年龄，街道地址和工作职位等

这是我的RegisterViewModel

public class RegisterViewModel
{
        //RoleID
        public int Id { get; set; }
        [Required(AllowEmptyStrings = false)]
        //RoleName
        [Display(Name = "RoleName")]
        public string Name { get; set; }
        public IEnumerable<SelectListItem> RolesList { get; set; }
        //Department and Depot
        public int DepotID { get; set; }
        public IEnumerable<SelectListItem> DepotList { get; set; }
        public IEnumerable<SelectListItem> DepartmentList { get; set; }
        public int DepartmentID { get; set; }
}

这是我的POST和GET方法注册AccountController.cs

    // GET: /Account/Register
    [AllowAnonymous]
    public ActionResult Register()
    {
        RegisterViewModel model = new RegisterViewModel();
        ConfigureRegisterViewModel(model);
        return View(model);
    }
    //
    // POST: /Account/Register
    [HttpPost]
    [AllowAnonymous]
    [ValidateAntiForgeryToken]
    public async Task<ActionResult> Register(RegisterViewModel model)
    {
        if (!ModelState.IsValid)
        {
            ConfigureRegisterViewModel(model);
            return View(model);
        }
            var user = new ApplicationUser() {
                UserName = model.Email,
                Email = model.Email,
                FirstMidName = model.FirstMidName,
                LastName = model.LastName,
                EnrollmentDate = model.EnrollmentDate,
                DepotID = model.DepotID,
                DepartmentID = model.DepartmentID,
                Id = model.Id //My RoleID
            };
            var result = await UserManager.CreateAsync(user, model.Password);
            if (result.Succeeded)
            {
                var code = await UserManager.GenerateEmailConfirmationTokenAsync(user.Id);
                var callbackUrl = Url.Action("ConfirmEmail", "Account", new { userId = user.Id, code = code }, protocol: Request.Url.Scheme);
                await UserManager.SendEmailAsync(user.Id, "Confirm your account", "Please confirm your account by clicking this link: <a href='"" + callbackUrl + "'">link</a>");
                ViewBag.Link = callbackUrl;
            return View("DisplayEmail");
            }
        AddErrors(result);
        // If we got this far, something failed, redisplay form
        ConfigureRegisterViewModel(model);
        return View(model);
    }
    private void ConfigureRegisterViewModel(RegisterViewModel model)
    {
        IEnumerable<Department> departments = db.Departments.OrderBy(u => u.DepartmentName);
        model.DepartmentList = departments.Select(a => new SelectListItem
        {
            Value = a.DepartmentID.ToString(),
            Text = a.DepartmentName.ToString()
        });
        IEnumerable<Depot> depots = db.Depots.OrderBy(u => u.DepotName);
        model.DepotList = depots.Select(a => new SelectListItem
        {
            Value = a.DepotID.ToString(),
            Text = a.DepotName.ToString()
        });
        IEnumerable<RegisterViewModel> roles = db.Roles.OrderBy(u => u.Name); <-- ERROR HERE 
        model.RolesList = roles.Select(a => new SelectListItem
        {
            Value = a.Id.ToString(),
            Text = a.Name.ToString()
        });
    }

Register.cshtml

            <div class="form-group">
                @Html.LabelFor(m => m.Id, new { @class = "col-md-2 control-label" })
                <div class="col-md-10">
                    @Html.DropDownListFor(m => m.Id, Model.RolesList, "Please select", new { @class = "form-control" })
                </div>
            </div>

此代码仅供参考

IdentityModel.cs (ApplicationUser类)

namespace RecreationalServicesTicketingSystem.Models
{
    public class ApplicationUserLogin : IdentityUserLogin<int> { }
    public class ApplicationUserClaim : IdentityUserClaim<int> { }
    public class ApplicationUserRole : IdentityUserRole<int> { }
    public class ApplicationRole : IdentityRole<int, ApplicationUserRole>, IRole<int>
    {
        public string Description { get; set; }
        public ApplicationRole() : base() { }
        public ApplicationRole(string name)
            : this()
        {
            this.Name = name;
        }
        public ApplicationRole(string name, string description)
            : this(name)
        {
            this.Description = description;
        }
    }
    public class ApplicationUser : IdentityUser<int, ApplicationUserLogin, ApplicationUserRole, ApplicationUserClaim>, IUser<int>
    {
        public async Task<ClaimsIdentity>
            GenerateUserIdentityAsync(UserManager<ApplicationUser, int> manager)
        {
            var userIdentity = await manager
                .CreateIdentityAsync(this, DefaultAuthenticationTypes.ApplicationCookie);
            return userIdentity;
        }
        public bool IsAdministrator { get; set; }
        [StringLength(50, MinimumLength = 1)]
        public string LastName { get; set; }
        [StringLength(50, MinimumLength = 1, ErrorMessage = "First name cannot be longer than 50 characters.")]
        [Column("FirstName")]
        public string FirstMidName { get; set; }
        public string FullName
        {
            get { return FirstMidName + " " + LastName; }
        }
        [DataType(DataType.Date)]
        [DisplayFormat(DataFormatString = "{0:yyyy-MM-dd}", ApplyFormatInEditMode = true)]
        public DateTime EnrollmentDate { get; set; }
        public int DepartmentID { get; set; }
        [ForeignKey("DepartmentID")]
        public virtual Department Department { get; set; }
        public int DepotID { get; set; }
        [ForeignKey("DepotID")]
        public virtual Depot Depot { get; set; }
        public virtual ICollection<Ticket> Tickets { get; set; }

        //Adding Roles to Register page code start
        //RoleID
        public int Id { get; set; }
        [Required(AllowEmptyStrings = false)]
        //RoleName
        [Display(Name = "RoleName")]
        public string Name { get; set; }
        //Adding Roles to Register page code end
    }

    public class ApplicationDbContext
        : IdentityDbContext<ApplicationUser, ApplicationRole, int,
        ApplicationUserLogin, ApplicationUserRole, ApplicationUserClaim>
    {
        public ApplicationDbContext()
            : base("DefaultConnection")
        {
        }
        static ApplicationDbContext()
        {
            Database.SetInitializer<ApplicationDbContext>(new ApplicationDbInitializer());
        }

        public static ApplicationDbContext Create()
        {
            return new ApplicationDbContext();
        }

        public DbSet<Ticket> Tickets { get; set; }
        public DbSet<Category> Categories { get; set; }
        public DbSet<Department> Departments { get; set; }
        public DbSet<Depot> Depots { get; set; }

    }

    public class ApplicationUserStore :
    UserStore<ApplicationUser, ApplicationRole, int,
    ApplicationUserLogin, ApplicationUserRole, ApplicationUserClaim>, IUserStore<ApplicationUser, int>, IDisposable
    {
        public ApplicationUserStore()
            : this(new IdentityDbContext())
        {
            base.DisposeContext = true;
        }
        public ApplicationUserStore(DbContext context)
            : base(context)
        {
        }
    }

    public class ApplicationRoleStore
    : RoleStore<ApplicationRole, int, ApplicationUserRole>,
    IQueryableRoleStore<ApplicationRole, int>,
    IRoleStore<ApplicationRole, int>, IDisposable
    {
        public ApplicationRoleStore()
            : base(new IdentityDbContext())
        {
            base.DisposeContext = true;
        }
        public ApplicationRoleStore(DbContext context)
            : base(context)
        {
        }


    }

}