public ActionResult EnrollInClass(EnrollInClassModel enrollInClassModel)
        {
            ViewBag.Message = "Classes Available to Enroll In";

            var user = (Models.UserModel)Session["User"];

            classManager.AddClass(enrollInClassModel.ClassId, user.Id);

            return(Redirect("~/Home/StudentClasses"));
        }
        public ActionResult EnrollInClass()
        {
            ViewBag.Message = "Classes Available to Enroll In";

            var user = (Models.UserModel)Session["User"];

            var classes = classManager.Classes
                          .Select(c => new Models.ClassModel(c.Id, c.Name, c.Description, c.Price))
                          .ToList();

            var studentClasses = classManager.StudentClasses(user.Id)
                                 .Select(c => new Models.ClassModel(c.Id, c.Name, c.Description, c.Price))
                                 .ToArray();

            classes.RemoveAll(c => studentClasses.Any(s => s.Name == c.Name));

            var openClasses = classes.ToArray();

            var enrollInClassModel = new EnrollInClassModel {
                Classes = openClasses, ClassId = 0
            };

            return(View(enrollInClassModel));
        }