/**
  * Store a user survey in storage.
  *
  * @param Request $request
  * @param Survey $survey
  * @return \Illuminate\Http\RedirectResponse
  */
 public function userSurvey(Request $request, Survey $survey)
 {
     // add validation rules and error messages to insure all radio buttons of the survey are filled out
     $rules = [];
     $messages = [];
     for ($i = 1; $i <= $survey->size(); $i++) {
         $rules['radio.' . $i] = 'required';
         $messages['radio.' . $i . '.required'] = 'Survey Question ' . $i . ' is required.';
     }
     $this->validate($request, $rules, $messages);
     //store answers in database if all questions have been filled out
     $numResponses = count($request->input('radio'));
     for ($i = 1; $i <= $numResponses; $i++) {
         $answer = SurveyAnswer::findOrFail($request->input('radio.' . $i));
         Auth::user()->surveys()->attach($survey->id, ['survey_question_id' => $answer->survey_question_id, 'survey_answer_id' => $answer->id]);
     }
     return back();
 }