/**
  * Store a newly created resource in storage.
  *
  * @param  Request  $request
  * @return Response
  */
 public function store(TrainingFormRequest $request)
 {
     $exercise_fields = ['exercise_id', 'reps', 'series', 'duration'];
     $exercise_data = [];
     $training = new Training();
     $training->user_id = Auth::user()->id;
     $training->save();
     foreach ($exercise_fields as $field) {
         $data = $request->input($field);
         foreach ($data as $key => $value) {
             $exercise_data[$key][$field] = $value;
         }
     }
     $user_id = Auth::user()->id;
     foreach ($exercise_data as &$exercise) {
         $exercise['user_id'] = $user_id;
     }
     $training->exercises()->attach($exercise_data);
     return response()->json(array('success' => true));
 }