public ActionResult Edit(string id)
        {
            var gym =
                RavenSession
                    .Load<Gym>(id);

            var model = new GymEditCommand(gym);
            return PartialView(model);
        }
        public JsonDotNetResult Edit(GymEditCommand command)
        {
            return Execute(
                action: () =>
                {
                    var gym =
                        RavenSession
                            .Load<Gym>(command.GymId);

                    gym.Update(command);

                    RavenSession.SaveChanges();

                    return new JsonDotNetResult(command);
                });
        }