public function store($groupId)
 {
     $date = Input::get('date');
     $time = Input::get('time');
     try {
         DB::transaction(function () use($groupId, $date, $time) {
             foreach (Input::get('customers') as $customerId) {
                 $att = new \App\Attendance(['group_id' => $groupId, 'customer_id' => $customerId, 'was_at' => sprintf('%s %s', $date, $time)]);
                 $att->save();
             }
         });
     } catch (Exception $e) {
         redirect(route('attendance.index', $groupId))->with('error', $e->getMessage());
     }
     return redirect(route('attendance.index', $groupId))->with('status', 'Attendance saved');
 }