<?php

use Symfony\Component\Validator\Constraint;
use Symfony\Component\Validator\ConstraintValidator;
use Symfony\Component\Validator\Exception\UnexpectedTypeException;
use Symfony\Component\Validator\ValidatorBuilder;

/**
 * @Annotation
 * @Target({"PROPERTY", "METHOD", "ANNOTATION"})
 */
class Bacon extends Constraint
{
    public $message = 'The validator checks bacon and your argument is invalid.';
}

class BaconValidator extends ConstraintValidator
{
    public function validate($value, Constraint $constraint)
    {
        if (!$constraint instanceof Bacon) {
            throw new UnexpectedTypeException($constraint, Bacon::CLASS);
        }

        if ('bacon' === strtolower($value)) {
            return;
        }

        $this->context->addViolation($constraint->message, array(
            '{{ value }}' => $this->formatValue($value),
        ));
    }
}

// see http://php.budgegeria.de/inyvqngvba6 for how symfony validation with annotation works

class Foo
{
    /**
     * @Bacon
     */
    public $breakfast;
}

$foo = new Foo();
$foo->breakfast = 'not bacon';

$validator = (new ValidatorBuilder())
    ->enableAnnotationMapping()
    ->getValidator();

$violationList = $validator->validate($foo);

foreach($violationList as $v) {
    echo $v->getMessage() . PHP_EOL;
}

The validator checks bacon and your argument is invalid.

• JsonResponse - Symfony has a lot of different Response classes
• Dump an array to Yaml
• Create new instances with every call of a Symfony service

PHP 8.2, Laminas MVC 3.2, Symfony 5.2, Laravel 8.28, PHPUnit 9.5, Doctrine ORM 2.8