SerializationTestNormalizer.php

<?php

namespace Drupal\serialization_test;

use Symfony\Component\Serializer\Normalizer\NormalizerInterface;
class SerializationTestNormalizer implements NormalizerInterface {
  
  /**
   * The format that this Normalizer supports.
   *
   * @var string
   */
  protected static $format = 'serialization_test';
  
  /**
   * {@inheritdoc}
   */
  public function normalize($object, $format = NULL, array $context = []) : array|string|int|float|bool|\ArrayObject|null {
    $normalized = (array) $object;
    // Add identifying value that can be used to verify that the expected
    // normalizer was invoked.
    $normalized['normalized_by'] = 'SerializationTestNormalizer';
    return $normalized;
  }
  
  /**
   * {@inheritdoc}
   */
  public function supportsNormalization($data, ?string $format = NULL, array $context = []) : bool {
    return static::$format === $format;
  }
  
  /**
   * {@inheritdoc}
   */
  public function getSupportedTypes(?string $format) : array {
    return [
      \stdClass::class => TRUE,
    ];
  }

}