namespace AppBundle\Action;
use Sensio\Bundle\FrameworkExtraBundle\Configuration\Method;
use Symfony\Component\Routing\Annotation\Route;
use AppBundle\Entity\Entity;
use Doctrine\ORM\EntityManagerInterface;
class EntityBulk
{
    /**
     *
     * @var EntityManagerInterface $manager
     */
    protected $entityManager;
    public function __construct(EntityManagerInterface $manager)
    {
        $this->entityManager = $manager;
    }
    /**
     * @Route(name="api_entity_post_bulk", path="/runner_subscriptions/bulk", defaults={"_api_resource_class"=Entity::class, "_api_collection_operation_name"="bulk"})
     *
     * @method ("POST")
     */
    public function __invoke($data)
    {
        array_map(function ($item) {
            $this->entityManager->persist($item);
        }, $data);
        $this->entityManager->flush();
        return $data;
    }
}

<?php
namespace AppBundle\Serializer;
use Symfony\Component\Serializer\Normalizer\NormalizerInterface;
use Symfony\Component\Serializer\Normalizer\DenormalizerInterface;
use AppBundle\Entity;
use \InvalidArgumentException;
class CustomNormalizer implements NormalizerInterface, DenormalizerInterface
{
    /**
     *
     * @var NormalizerInterface $normalizer
     */
    private $normalizer;
    /**
     *
     * @param NormalizerInterface $normalizer
     * @throws InvalidArgumentException
     */
    public function __construct(NormalizerInterface $normalizer)
    {
        if (!$normalizer instanceof DenormalizerInterface) {
            throw new InvalidArgumentException('The normalizer must implement the DenormalizerInterface');
        }
        $this->normalizer = $normalizer;
    }
    /**
     *
     * {@inheritDoc}
     * @see \Symfony\Component\Serializer\Normalizer\DenormalizerInterface::denormalize()
     */
    public function denormalize($data, $class, $format = null, array $context = [])
    {
        if (is_array($data) && Entity::class === $class) {
            // bulk operation must update on POST as PUT is only allowed for item and not collection
            // https://api-platform.com/docs/core/operations
            $context['api_allow_update'] = true;
            return array_map(function($item) use ($class, $format, $context) {
                return $this->normalizer->denormalize($item, $class, $format, $context);
            }, $data);
        }
        return $this->normalizer->denormalize($data, $class, $format, $context);
    }
    /**
     *
     * {@inheritDoc}
     * @see \Symfony\Component\Serializer\Normalizer\DenormalizerInterface::supportsDenormalization()
     */
    public function supportsDenormalization($data, $type, $format = null)
    {
        return $this->normalizer->supportsDenormalization($data, $type, $format);
    }
    /**
     *
     * {@inheritDoc}
     * @see \Symfony\Component\Serializer\Normalizer\NormalizerInterface::normalize()
     */
    public function normalize($object, $format = null, array $context = [])
    {
        return $this->normalizer->normalize($object, $format, $context);
    }
    /**
     *
     * {@inheritDoc}
     * @see \Symfony\Component\Serializer\Normalizer\NormalizerInterface::supportsNormalization()
     */
    public function supportsNormalization($data, $format = null)
    {
        return $this->normalizer->supportsNormalization($data, $format);
    }
}