frontend\controllers\AddressController::actionBuildings PHP Method

    public function actionBuildings($id)
    {
        Yii::$app->response->format = Response::FORMAT_JSON;
        $output = ['status' => 'ok', 'html' => ''];
        $list = Building::getKeyValuePairs($id);
        foreach ($list as $key => $name) {
            $output['html'] .= "<option value=\"{$key}\">{$name}</option>";
        }
        return $output;
    }