public ActionResult Issue(IssueModel model)
        {
            if (!UserModel.CurrentUserLoggedIn)
            {
                return(RedirectToAction("Index", "Library"));
            }

            List <String> BooksInPosession = IssueModel.BooksInPosession();

            int count = BooksInPosession.Count();

            count = count / 3;
            if (count > 6)
            {
                @ViewBag.Error = "U heeft al teveel boeken in uw bezit";
                return(View());
            }

            if (model.Issue())
            {
                @ViewBag.Error = "Veel leesplezier";
            }
            else
            {
                @ViewBag.Error = "Er is helaas iets fout gegaan, probeer het opnieuw.";
            }

            return(View());
        }