How to parse only individual fields and not the whole object?

Question

Yii

$userArray = ArrayHelper::toArray($user);
        return json_encode(['answer'=>1,'customer'=>$userArray]);   //парсятся все поля

return json_encode(['answer'=>1,'customer'=>$user]); //парсится объект с полями и методами

How to parse only certain fields?

Answer 1

return json_encode(['answer'=>1, 'customer'=>array_intersect_key($userArray, ['name' => true, 'email' => true])]);