public IActionResult Add(int movieId) { var userId = userManager.GetUserId(HttpContext.User); var existingMovie = watchlistData.GetWatchlistByMovie(movieId, userId); if (existingMovie == null) { var watchlist = new Watchlist { MovieId = movieId, UserId = userId }; watchlistData.AddMovieToWatchlist(watchlist); TempData["ResultMessage"] = "The movie has been added to your watchlist."; TempData["AlertClass"] = "alert alert-success"; } else { TempData["ResultMessage"] = "This movie already exists in your watchlist."; TempData["AlertClass"] = "alert alert-danger"; } return(RedirectToAction(nameof(Index))); }