// composer require symfony/serializer:"5.4.*" doctrine/annotations symfony/property-access
<?php
require_once __DIR__.'/vendor/autoload.php';

use Doctrine\Common\Annotations\AnnotationReader;
use Symfony\Component\PropertyInfo\Extractor\ReflectionExtractor;
use Symfony\Component\Serializer\Annotation\Context;
use Symfony\Component\Serializer\Mapping\Factory\ClassMetadataFactory;
use Symfony\Component\Serializer\Mapping\Loader\AnnotationLoader;
use Symfony\Component\Serializer\NameConverter\CamelCaseToSnakeCaseNameConverter;
use Symfony\Component\Serializer\Normalizer\DateTimeNormalizer;
use Symfony\Component\Serializer\Normalizer\ObjectNormalizer;
use Symfony\Component\Serializer\Serializer;

class Item
{
    /**
     * @Context({ DateTimeNormalizer::FORMAT_KEY = "d/m/Y" })
     */
    public \DateTime $createdAt;
}

$classMetadataFactory = new ClassMetadataFactory(new AnnotationLoader(new AnnotationReader()));
$objectNormalizer = new ObjectNormalizer($classMetadataFactory, new CamelCaseToSnakeCaseNameConverter(), null, new ReflectionExtractor());
$normalizers = [new DateTimeNormalizer(), $objectNormalizer];
new Serializer($normalizers, []);

// outputs 2011-07-28
echo ($objectNormalizer->denormalize(['createdAt' => '28/07/2011'], Item::class))->createdAt->format('Y-m-d') . PHP_EOL;

// crashes because 'created_at' !== 'createdAt'
echo ($objectNormalizer->denormalize(['created_at' => '28/07/2011'], Item::class))->createdAt->format('Y-m-d') . PHP_EOL;