Yii2 Conditional Validator

public function rules()
{
    return [
        [['customer_type'], ConditionalValidator::className(),
            'if' => [
                [['customer_type'], 'compare', 'compareValue' => 'active']
            ],
            'then' => [
                [['birthdate', 'city'], 'required']
            ]
        ]
    ];
}