public ActionResult Add(int id, AddUserLicenseViewModel model)
        {
            try
            {
                if (!ModelState.IsValid)
                {
                    return(View(model));
                }

                var parsedBuyDate = DateTime.ParseExact(model.BuyDate,
                                                        "d",
                                                        CultureInfo.CreateSpecificCulture("de-DE"));

                var expiryDate = parsedBuyDate.AddYears(model.LicenseYears);

                var customerModules = new Customer_Modules();
                customerModules.BuyDate    = parsedBuyDate;
                customerModules.ExpiryDate = expiryDate;
                customerModules.ModId      = model.ModId;

                _db.Users.Single(u => u.UId == id).Customer_Modules.Add(customerModules);
                _db.SaveChanges();
                TempData["uihint"] = new UiHint("Erfolg!", "Die Lizenz wurde hinzugefügt!",
                                                new { @class = "alert alert-success" });
                return(RedirectToAction("Details", "User", new { id = id }));
            }
            catch
            {
                return(View(model));
            }
        }
        public ActionResult Add(int id)
        {
            var viewModel = new AddUserLicenseViewModel {
                User = _db.Users.Single(u => u.UId == id)
            };

            if (viewModel.PopulateSelectList())
            {
                return(View(viewModel));
            }
            TempData["uihint"] = new UiHint("Das geht nicht.",
                                            "Der Benutzer verfügt schon über die Lizenzen aller Module!",
                                            new { @class = "alert alert-error" });
            return(RedirectToAction("Details", "User", new { id = id }));
        }