public function getDeviceList(Request $request)
 {
     $model = $request->model;
     $company_id = $request->company_id;
     $hasvehicle = $request->hasvehicle;
     $devicesquery = Device::hasvehicle($hasvehicle);
     if ($company_id != '') {
         $devicesquery = $devicesquery->where('company_id', $company_id);
     }
     if ($model != '') {
         $devicesquery = $devicesquery->where('model', $model);
     }
     $result = $devicesquery->lists("serial", "id")->all();
     return json_encode($result);
 }