MarkupNormalizer.php

<?php

namespace Drupal\serialization\Normalizer;

use Drupal\Component\Render\MarkupInterface;

/**
 * Normalizes MarkupInterface objects into a string.
 */
class MarkupNormalizer extends NormalizerBase {
  use SchematicNormalizerTrait;
  use JsonSchemaReflectionTrait;
  
  /**
   * {@inheritdoc}
   */
  public function doNormalize($object, $format = NULL, array $context = []) : array|string|int|float|bool|\ArrayObject|null {
    return (string) $object;
  }
  
  /**
   * {@inheritdoc}
   */
  public function getNormalizationSchema(mixed $object, array $context = []) : array {
    return $this->getJsonSchemaForMethod($object, '__toString', [
      'type' => 'string',
      'description' => 'May contain HTML markup.',
    ]);
  }
  
  /**
   * {@inheritdoc}
   */
  public function getSupportedTypes(?string $format) : array {
    return [
      MarkupInterface::class => TRUE,
    ];
  }

}