public IActionResult Submitted(IndexViewModel svm) { //if form data are valid, this checks authkey too if (ModelState.IsValid) { IndexViewModel model = new IndexViewModel() { FirstName = svm.FirstName, LastName = svm.LastName, Email = svm.Email, Telephone = svm.Telephone, Birthday = svm.Birthday, Authentication = svm.Authentication }; //save submission in file if (svm.SaveSubmission()) { //delete used key from file, if above submission was completed svm.DeleteAuthenticationKey(svm.Authentication); } return(View(svm)); } else //form data is not valid { return(View("Index")); } }