public ActionResult Delete([DataSourceRequest] DataSourceRequest request, UserEditModel user)
        {
            var existingUser = this.db.AppUsers.All().FirstOrDefault(u => u.Id == user.Id);
            if (existingUser != null)
            {
                this.db.AppUsers.Delete(existingUser);
            }

            return Json(new[] { user }.ToDataSourceResult(request, ModelState));
        }
        public ActionResult Update([DataSourceRequest] DataSourceRequest request, UserEditModel user)
        {
            var existingUser = this.db.AppUsers.All().FirstOrDefault(u => u.Id == user.Id);
            if (existingUser != null && ModelState.IsValid)
            {
                existingUser.FullName = user.FullName;
                existingUser.Email = user.Email;
                existingUser.AboutMe = user.AboutMe;
                this.db.SaveChanges();
            }

            return Json(new[] { user }.ToDataSourceResult(request, ModelState));
        }