public ActionResult AddStudent(string courseId)
        {
            var userId = User.Identity.GetUserId();

            if (UserRolesModel.IsTeacher(userId) || UserRolesModel.IsAdmin(userId))
            {
                return(View(CourseStudentEditModel.CourseStudentEdit(courseId)));
            }
            else
            {
                return(RedirectToAction("Unauthorized", "User"));
            }
        }
        public ActionResult AddStudentPost(CourseStudentEditModel model)
        {
            var userId = User.Identity.GetUserId();

            if (UserRolesModel.IsTeacher(userId) || UserRolesModel.IsAdmin(userId))
            {
                JsonResult json = new JsonResult();
                json.Data = CourseStudentEditModel.CourseStudentEditPost(model).CourseId;
                return(json);
            }
            else
            {
                return(RedirectToAction("Unauthorized", "User"));
            }
        }
        public ActionResult RemoveStudentPost(string id)
        {
            var userId = User.Identity.GetUserId();

            if (UserRolesModel.IsTeacher(userId) || UserRolesModel.IsAdmin(userId))
            {
                JsonResult json = new JsonResult();
                var        run  = CourseStudentEditModel.CourseStudentRemovePost(id);
                json.Data = "ok";
                json.JsonRequestBehavior = JsonRequestBehavior.AllowGet;
                return(json);
            }
            else
            {
                return(RedirectToAction("Unauthorized", "User"));
            }
        }