yii of rules validation rules

 public function rules() {
        return [
            [['id'], 'integer'],
            [['id'], 'required'],
            [['files'], 'file', 'maxSize' => 50 * 1024 * 1024, 'maxFiles' => 10, 'mimeTypes' => ['image/*', 'audio/*', 'video/*']],
        ];
    }