You can create a custom constraint by extending the base constraint class, :class:`Symfony\\Component\\Validator\\Constraint`. As an example you're going to create a basic validator that checks if a string contains only alphanumeric characters.
First you need to create a Constraint class and extend :class:`Symfony\\Component\\Validator\\Constraint`:
.. configuration-block::
.. code-block:: php-annotations
// src/Validator/ContainsAlphanumeric.php
namespace App\Validator;
use Symfony\Component\Validator\Constraint;
/**
* @Annotation
*/
class ContainsAlphanumeric extends Constraint
{
public string $message = 'The string "{{ string }}" contains an illegal character: it can only contain letters or numbers.';
// If the constraint has configuration options, define them as public properties
public string $mode = 'strict';
}
.. code-block:: php-attributes
// src/Validator/ContainsAlphanumeric.php
namespace App\Validator;
use Symfony\Component\Validator\Constraint;
#[\Attribute]
class ContainsAlphanumeric extends Constraint
{
public $message = 'The string "{{ string }}" contains an illegal character: it can only contain letters or numbers.';
public $mode = 'strict';
// all configurable options must be passed to the constructor
public function __construct(?string $mode = null, ?string $message = null, ?array $groups = null, $payload = null)
{
parent::__construct([], $groups, $payload);
$this->mode = $mode ?? $this->mode;
$this->message = $message ?? $this->message;
}
}
Add @Annotation or #[\Attribute] to the constraint class if you want to
use it as an annotation/attribute in other classes.
.. versionadded:: 5.2
The ability to use PHP attributes to configure constraints was introduced in
Symfony 5.2. Prior to this, Doctrine Annotations were the only way to
annotate constraints.
As you can see, a constraint class is fairly minimal. The actual validation is
performed by another "constraint validator" class. The constraint validator
class is specified by the constraint's validatedBy() method, which
has this default logic:
// in the base Symfony\Component\Validator\Constraint class
public function validatedBy()
{
return static::class.'Validator';
}
In other words, if you create a custom Constraint (e.g. MyConstraint),
Symfony will automatically look for another class, MyConstraintValidator
when actually performing the validation.
The validator class only has one required method validate():
// src/Validator/ContainsAlphanumericValidator.php
namespace App\Validator;
use Symfony\Component\Validator\Constraint;
use Symfony\Component\Validator\ConstraintValidator;
use Symfony\Component\Validator\Exception\UnexpectedTypeException;
use Symfony\Component\Validator\Exception\UnexpectedValueException;
class ContainsAlphanumericValidator extends ConstraintValidator
{
public function validate($value, Constraint $constraint): void
{
if (!$constraint instanceof ContainsAlphanumeric) {
throw new UnexpectedTypeException($constraint, ContainsAlphanumeric::class);
}
// custom constraints should ignore null and empty values to allow
// other constraints (NotBlank, NotNull, etc.) to take care of that
if (null === $value || '' === $value) {
return;
}
if (!is_string($value)) {
// throw this exception if your validator cannot handle the passed type so that it can be marked as invalid
throw new UnexpectedValueException($value, 'string');
// separate multiple types using pipes
// throw new UnexpectedValueException($value, 'string|int');
}
// access your configuration options like this:
if ('strict' === $constraint->mode) {
// ...
}
if (preg_match('/^[a-zA-Z0-9]+$/', $value, $matches)) {
return;
}
// the argument must be a string or an object implementing __toString()
$this->context->buildViolation($constraint->message)
->setParameter('{{ string }}', $value)
->addViolation();
}
}
Inside validate(), you don't need to return a value. Instead, you add violations
to the validator's context property and a value will be considered valid
if it causes no violations. The buildViolation() method takes the error
message as its argument and returns an instance of
:class:`Symfony\\Component\\Validator\\Violation\\ConstraintViolationBuilderInterface`.
The addViolation() method call finally adds the violation to the context.
You can use custom validators like the ones provided by Symfony itself:
.. configuration-block::
.. code-block:: php-annotations
// src/Entity/User.php
namespace App\Entity;
use App\Validator as AcmeAssert;
use Symfony\Component\Validator\Constraints as Assert;
class User
{
// ...
/**
* @Assert\NotBlank
* @AcmeAssert\ContainsAlphanumeric(mode="loose")
*/
protected string $name = '';
// ...
}
.. code-block:: php-attributes
// src/Entity/AcmeEntity.php
namespace App\Entity;
use App\Validator as AcmeAssert;
use Symfony\Component\Validator\Constraints as Assert;
class AcmeEntity
{
// ...
#[Assert\NotBlank]
#[AcmeAssert\ContainsAlphanumeric(mode: 'loose')]
protected $name;
// ...
}
.. code-block:: yaml
# config/validator/validation.yaml
App\Entity\User:
properties:
name:
- NotBlank: ~
- App\Validator\ContainsAlphanumeric:
mode: 'loose'
.. 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 https://symfony.com/schema/dic/constraint-mapping/constraint-mapping-1.0.xsd">
<class name="App\Entity\User">
<property name="name">
<constraint name="NotBlank"/>
<constraint name="App\Validator\ContainsAlphanumeric">
<option name="mode">loose</option>
</constraint>
</property>
</class>
</constraint-mapping>
.. code-block:: php
// src/Entity/User.php
namespace App\Entity;
use App\Validator\ContainsAlphanumeric;
use Symfony\Component\Validator\Constraints\NotBlank;
use Symfony\Component\Validator\Mapping\ClassMetadata;
class User
{
protected string $name = '';
// ...
public static function loadValidatorMetadata(ClassMetadata $metadata): void
{
$metadata->addPropertyConstraint('name', new NotBlank());
$metadata->addPropertyConstraint('name', new ContainsAlphanumeric(['mode' => 'loose']));
}
}
If your constraint contains options, then they should be public properties on the custom Constraint class you created earlier. These options can be configured like options on core Symfony constraints.
If you're using the :ref:`default services.yaml configuration <service-container-services-load-example>`,
then your validator is already registered as a service and :doc:`tagged </service_container/tags>`
with the necessary validator.constraint_validator. This means you can
:ref:`inject services or configuration <services-constructor-injection>` like any other service.
If you want to add some configuration options to your custom constraint, first define those options as public properties on the constraint class:
.. configuration-block::
.. code-block:: php-annotations
// src/Validator/Foo.php
namespace App\Validator;
use Symfony\Component\Validator\Constraint;
/**
* @Annotation
*/
class Foo extends Constraint
{
public $mandatoryFooOption;
public $message = 'This value is invalid';
public $optionalBarOption = false;
public function __construct(
$mandatoryFooOption,
?string $message = null,
?bool $optionalBarOption = null,
?array $groups = null,
$payload = null,
array $options = []
) {
if (\is_array($mandatoryFooOption)) {
$options = array_merge($mandatoryFooOption, $options);
} elseif (null !== $mandatoryFooOption) {
$options['value'] = $mandatoryFooOption;
}
parent::__construct($options, $groups, $payload);
$this->message = $message ?? $this->message;
$this->optionalBarOption = $optionalBarOption ?? $this->optionalBarOption;
}
public function getDefaultOption()
{
// If no associative array is passed to the constructor this
// property is set instead.
return 'mandatoryFooOption';
}
public function getRequiredOptions()
{
// return names of options which must be set.
return ['mandatoryFooOption'];
}
}
.. code-block:: php-attributes
// src/Validator/Foo.php
namespace App\Validator;
use Symfony\Component\Validator\Constraint;
#[\Attribute]
class Foo extends Constraint
{
public $mandatoryFooOption;
public $message = 'This value is invalid';
public $optionalBarOption = false;
public function __construct(
$mandatoryFooOption,
?string $message = null,
?bool $optionalBarOption = null,
?array $groups = null,
$payload = null,
array $options = []
) {
if (\is_array($mandatoryFooOption)) {
$options = array_merge($mandatoryFooOption, $options);
} elseif (null !== $mandatoryFooOption) {
$options['value'] = $mandatoryFooOption;
}
parent::__construct($options, $groups, $payload);
$this->message = $message ?? $this->message;
$this->optionalBarOption = $optionalBarOption ?? $this->optionalBarOption;
}
public function getDefaultOption()
{
return 'mandatoryFooOption';
}
public function getRequiredOptions()
{
return ['mandatoryFooOption'];
}
}
Then, inside the validator class you can access these options directly via the
constraint class passes to the validate() method:
class FooValidator extends ConstraintValidator
{
public function validate($value, Constraint $constraint)
{
// access any option of the constraint
if ($constraint->optionalBarOption) {
// ...
}
// ...
}
}
When using this constraint in your own application, you can pass the value of the custom options like you pass any other option in built-in constraints:
.. configuration-block::
.. code-block:: php-annotations
// src/Entity/AcmeEntity.php
namespace App\Entity;
use App\Validator as AcmeAssert;
use Symfony\Component\Validator\Constraints as Assert;
class AcmeEntity
{
// ...
/**
* @Assert\NotBlank
* @AcmeAssert\Foo(
* mandatoryFooOption="bar",
* optionalBarOption=true
* )
*/
protected $name;
// ...
}
.. code-block:: php-attributes
// src/Entity/AcmeEntity.php
namespace App\Entity;
use App\Validator as AcmeAssert;
use Symfony\Component\Validator\Constraints as Assert;
class AcmeEntity
{
// ...
#[Assert\NotBlank]
#[AcmeAssert\Foo(
mandatoryFooOption: 'bar',
optionalBarOption: true
)]
protected $name;
// ...
}
.. code-block:: yaml
# config/validator/validation.yaml
App\Entity\AcmeEntity:
properties:
name:
- NotBlank: ~
- App\Validator\Foo:
mandatoryFooOption: bar
optionalBarOption: true
.. 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 https://symfony.com/schema/dic/constraint-mapping/constraint-mapping-1.0.xsd">
<class name="App\Entity\AcmeEntity">
<property name="name">
<constraint name="NotBlank"/>
<constraint name="App\Validator\Foo">
<option name="mandatoryFooOption">bar</option>
<option name="optionalBarOption">true</option>
</constraint>
</property>
</class>
</constraint-mapping>
.. code-block:: php
// src/Entity/AcmeEntity.php
namespace App\Entity;
use App\Validator\ContainsAlphanumeric;
use Symfony\Component\Validator\Constraints\NotBlank;
use Symfony\Component\Validator\Mapping\ClassMetadata;
class AcmeEntity
{
public $name;
public static function loadValidatorMetadata(ClassMetadata $metadata)
{
$metadata->addPropertyConstraint('name', new NotBlank());
$metadata->addPropertyConstraint('name', new Foo([
'mandatoryFooOption' => 'bar',
'optionalBarOption' => true,
]));
}
}
In case you need to consistently apply a common set of constraints across your application, you can extend the :doc:`Compound constraint </reference/constraints/Compound>`.
.. versionadded:: 5.1
The ``Compound`` constraint was introduced in Symfony 5.1.
Besides validating a single property, a constraint can have an entire class as its scope.
For instance, imagine you also have a PaymentReceipt entity and you
need to make sure the email of the receipt payload matches the user's
email. First, create a constraint and override the getTargets() method:
// src/Validator/ConfirmedPaymentReceipt.php
namespace App\Validator;
use Symfony\Component\Validator\Constraint;
/**
* @Annotation
*/
class ConfirmedPaymentReceipt extends Constraint
{
public string $userDoesNotMatchMessage = 'User\'s e-mail address does not match that of the receipt';
public function getTargets(): string
{
return self::CLASS_CONSTRAINT;
}
}
Now, the constraint validator will get an object as the first argument to
validate():
// src/Validator/ConfirmedPaymentReceiptValidator.php
namespace App\Validator;
use Symfony\Component\Validator\Constraint;
use Symfony\Component\Validator\ConstraintValidator;
use Symfony\Component\Validator\Exception\UnexpectedValueException;
class ConfirmedPaymentReceiptValidator extends ConstraintValidator
{
/**
* @param PaymentReceipt $receipt
*/
public function validate($receipt, Constraint $constraint): void
{
if (!$receipt instanceof PaymentReceipt) {
throw new UnexpectedValueException($receipt, PaymentReceipt::class);
}
if (!$constraint instanceof ConfirmedPaymentReceipt) {
throw new UnexpectedValueException($constraint, ConfirmedPaymentReceipt::class);
}
$receiptEmail = $receipt->getPayload()['email'] ?? null;
$userEmail = $receipt->getUser()->getEmail();
if ($userEmail !== $receiptEmail) {
$this->context
->buildViolation($constraint->userDoesNotMatchMessage)
->atPath('user.email')
->addViolation();
}
}
}
Tip
The atPath() method defines the property with which the validation error is
associated. Use any :doc:`valid PropertyAccess syntax </components/property_access>`
to define that property.
A class constraint validator must be applied to the class itself:
.. configuration-block::
.. code-block:: php-annotations
// src/Entity/PaymentReceipt.php
namespace App\Entity;
use App\Validator\ConfirmedPaymentReceipt;
/**
* @ConfirmedPaymentReceipt
*/
class PaymentReceipt
{
// ...
}
.. code-block:: php-attributes
// src/Entity/AcmeEntity.php
namespace App\Entity;
use App\Validator as AcmeAssert;
#[AcmeAssert\ProtocolClass]
class AcmeEntity
{
// ...
}
.. code-block:: yaml
# config/validator/validation.yaml
App\Entity\PaymentReceipt:
constraints:
- App\Validator\ConfirmedPaymentReceipt: ~
.. 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
https://symfony.com/schema/dic/constraint-mapping/constraint-mapping-1.0.xsd">
<class name="App\Entity\PaymentReceipt">
<constraint name="App\Validator\ConfirmedPaymentReceipt"/>
</class>
</constraint-mapping>
.. code-block:: php
// src/Entity/PaymentReceipt.php
namespace App\Entity;
use App\Validator\ConfirmedPaymentReceipt;
use Symfony\Component\Validator\Mapping\ClassMetadata;
class PaymentReceipt
{
// ...
public static function loadValidatorMetadata(ClassMetadata $metadata): void
{
$metadata->addConstraint(new ConfirmedPaymentReceipt());
}
}
Use the :class:`Symfony\\Component\\Validator\\Test\\ConstraintValidatorTestCase` class to simplify writing unit tests for your custom constraints:
// tests/Validator/ContainsAlphanumericValidatorTest.php
namespace App\Tests\Validator;
use App\Validator\ContainsAlphanumeric;
use App\Validator\ContainsAlphanumericValidator;
use Symfony\Component\Validator\Test\ConstraintValidatorTestCase;
class ContainsAlphanumericValidatorTest extends ConstraintValidatorTestCase
{
protected function createValidator()
{
return new ContainsAlphanumericValidator();
}
public function testNullIsValid()
{
$this->validator->validate(null, new ContainsAlphanumeric());
$this->assertNoViolation();
}
/**
* @dataProvider provideInvalidConstraints
*/
public function testTrueIsInvalid(ContainsAlphanumeric $constraint)
{
$this->validator->validate('...', $constraint);
$this->buildViolation('myMessage')
->setParameter('{{ string }}', '...')
->assertRaised();
}
public function provideInvalidConstraints(): \Generator
{
yield [new ContainsAlphanumeric(message: 'myMessage')];
// ...
}
}