public ActionResult Index(RegistrationModel registrationModel) { if (!String.IsNullOrWhiteSpace(registrationModel.UserIdText)) { viewModel.CourseListItems = new List <SelectListItem>(); if (registrationModel.SelectedCourseNumber != null) { viewModel.SelectedCourseNumber = registrationModel.SelectedCourseNumber; viewModel.UserIdText = registrationModel.UserIdText; Course selectedCourse = viewModel.Courses.Where(c => c.CourseNumber == viewModel.SelectedCourseNumber).Single(); generateCourseList(); if (!(viewModel.TotalCredits + selectedCourse.Credits > 9)) { if (!viewModel.RegisteredCourses.Select(c => c.CourseNumber).Contains(selectedCourse.CourseNumber)) { viewModel.RegisteredCourses.Add(new RegisteredCourse(viewModel.UserIdText, viewModel.SelectedCourseNumber)); viewModel.SaveChanges(); viewModel.UserMessage = $"{selectedCourse.CourseNumber} registered!"; } else { viewModel.UserMessage = "Cannot select same course more than once."; } } else { viewModel.UserMessage = "Cannot register for more than 9 credits!"; } } else { viewModel.UserMessage = "Please select a course"; } generateCourseList(); return(View(viewModel)); } else { viewModel.UserMessage = "Please enter user id."; generateCourseList(); return(View(viewModel)); } }