TimestampItemNormalizer.php

<?php

namespace Drupal\serialization\Normalizer;

use Drupal\Core\Field\Plugin\Field\FieldType\TimestampItem;
use Drupal\Core\TypedData\Plugin\DataType\Timestamp;

/**
 * Converts values for TimestampItem to and from common formats.
 *
 * Overrides FieldItemNormalizer to use \Drupal\serialization\Normalizer\TimestampNormalizer
 *
 * Overrides FieldItemNormalizer to
 * - during normalization, add the 'format' key to assist consumers
 * - during denormalization, use \Drupal\serialization\Normalizer\TimestampNormalizer
 */
class TimestampItemNormalizer extends FieldItemNormalizer {
    
    /**
     * {@inheritdoc}
     */
    protected $supportedInterfaceOrClass = TimestampItem::class;
    
    /**
     * {@inheritdoc}
     */
    public function normalize($object, $format = NULL, array $context = []) {
        return parent::normalize($object, $format, $context) + [
            // 'format' is not a property on Timestamp objects. This is present to
            // assist consumers of this data.
'format' => \DateTime::RFC3339,
        ];
    }
    
    /**
     * {@inheritdoc}
     */
    protected function constructValue($data, $context) {
        if (!empty($data['format'])) {
            $context['datetime_allowed_formats'] = [
                $data['format'],
            ];
        }
        return [
            'value' => $this->serializer
                ->denormalize($data['value'], Timestamp::class, NULL, $context),
        ];
    }

}