public ActionResult InsertClientInMovie(int id)
        {
            var model = new ClientMovieViewModel()
            {
                Movie   = _context.Movies.Find(id),
                MovieId = id,
                Clients = _context.Clients.ToList()
            };

            return(View(model));
        }
        public ActionResult InsertClientInMovie(ClientMovieViewModel model)
        {
            var movie  = _context.Movies.Find(model.MovieId);
            var client = _context.Clients.Find(model.SelectedClientId);

            if (movie == null || client == null)
            {
                return(HttpNotFound());
            }

            movie.Clients.Add(client);
            _context.SaveChanges();
            return(RedirectToAction("ShowMovie", "Movies", new { id = movie.Id }));
        }