Luhn.rst

Luhn

This constraint is used to ensure that a credit card number passes the Luhn algorithm. It is useful as a first step to validating a credit card: before communicating with a payment gateway.

Applies to	:ref:`property or method <validation-property-target>`
Class	:class:`Symfony\\Component\\Validator\\Constraints\\Luhn`
Validator	:class:`Symfony\\Component\\Validator\\Constraints\\LuhnValidator`

Basic Usage

To use the Luhn validator, apply it to a property on an object that will contain a credit card number.

.. configuration-block::

    .. code-block:: php-attributes

        // src/Entity/Transaction.php
        namespace App\Entity;

        use Symfony\Component\Validator\Constraints as Assert;

        class Transaction
        {
            #[Assert\Luhn(message: 'Please check your credit card number.')]
            protected string $cardNumber;
        }

    .. code-block:: yaml

        # config/validator/validation.yaml
        App\Entity\Transaction:
            properties:
                cardNumber:
                    - Luhn:
                        message: Please check your credit card number.

    .. code-block:: xml

        <!-- config/validator/validation.xml -->
        <?xml version="1.0" encoding="UTF-8" ?>
        <constraint-mapping xmlns="http://symfony.com/schema/dic/constraint-mapping"
            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
            xsi:schemaLocation="http://symfony.com/schema/dic/constraint-mapping%20https://symfony.com/schema/dic/constraint-mapping/constraint-mapping-1.0.xsd">

            <class name="App\Entity\Transaction">
                <property name="cardNumber">
                    <constraint name="Luhn">
                        <option name="message">Please check your credit card number.</option>
                    </constraint>
                </property>
            </class>
        </constraint-mapping>

    .. code-block:: php

        // src/Entity/Transaction.php
        namespace App\Entity;

        use Symfony\Component\Validator\Constraints as Assert;
        use Symfony\Component\Validator\Mapping\ClassMetadata;

        class Transaction
        {
            // ...

            public static function loadValidatorMetadata(ClassMetadata $metadata): void
            {
                $metadata->addPropertyConstraint('cardNumber', new Assert\Luhn([
                    'message' => 'Please check your credit card number',
                ]));
            }
        }

Options

message

type: string default: Invalid card number.

The default message supplied when the value does not pass the Luhn check.

You can use the following parameters in this message:

Parameter	Description
{{ value }}	The current (invalid) value
{{ label }}	Corresponding form field label