如何在symfony 5中验证一些自定义约束

// src/Constraint/IsEven.php
namespace App\Constraint;

use Symfony\Component\Validator\Constraint;

class IsEven extends Constraint
{
    public $message = 'The value "{{ value }}" is not even.';

    public function validatedBy()
    {
        return get_class($this).'Validator';
    }
}

// src/Constraint/IsEvenValidator.php
namespace App\Constraint;

use Symfony\Component\Validator\Constraint;
use Symfony\Component\Validator\ConstraintValidator;

class IsEvenValidator extends ConstraintValidator
{
    public function validate($value, Constraint $constraint)
    {
        if (!is_int($value) || $value % 2 !== 0) {
            $this->context->buildViolation($constraint->message)
                ->setParameter('{{ value }}', $value)
                ->addViolation();
        }
    }
}

# config/services.yaml
services:
    App\Constraint\IsEvenValidator:
        tags:
            - { name: 'validator.constraint_validator', alias: 'is_even' }

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

use App\Constraint\IsEven;
use Symfony\Component\Validator\Constraints as Assert;

class MyEntity
{
    /**
     * @Assert\IsEven()
     */
    private $number;
    
    // ...
}

// src/Controller/MyController.php
namespace App\Controller;

use Symfony\Bundle\FrameworkBundle\Controller\AbstractController;
use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\HttpFoundation\Response;
use Symfony\Component\Validator\Validator\ValidatorInterface;
use App\Entity\MyEntity;

class MyController extends AbstractController
{
    public function myAction(Request $request, ValidatorInterface $validator): Response
    {
        $entity = new MyEntity();
        $entity->setNumber(3); // 这将触发验证错误

        $violations = $validator->validate($entity);

        if (count($violations) > 0) {
            // 处理验证错误
        }

        // ...
    }
}