public ActionResult Index(string id) { //see if this is a new story if (string.IsNullOrEmpty(id)) { return(View(new ComicStory())); } //fetch the data ComicStory comicStory; try { comicStory = _mongoRepositiry.GetStoryById(id); } catch (FormatException) { throw new ArgumentException("The story Id you have provided is invalid, or the story is corrupted"); } //ensure data is valid if (comicStory == null) { throw new ArgumentException("The story you requested could not be found"); } //return view return(View(comicStory)); }