Creating your own Node Entity Normalizer

Question

I am trying to create my own Node Entity Normalizer in Drupal 10 to get rid of the unnecessary JSON structure that comes out of the box. For example, instead of my API's returning

{
  "nid": [
    {
      "value": 7
    }
  ]
}

I want to make it return

{
  "nid": 7
}

So I've tried the following options in my custom module:

1. Typed Data Interface

example_normalizer.services.yml

services:
  example_normalizer.typed_data:
    class: Drupal\example_normalizer\Normalizer\CustomTypedDataNormalizer
    tags:
    - { name: normalizer, priority: 2 }

src/Normalizer/CustomTypedDataNormalizer.php

<?php
namespace Drupal\example_normalizer\Normalizer;
use Drupal\serialization\Normalizer\NormalizerBase;
/**
 * Converts typed data objects to arrays.
 */
class CustomTypedDataNormalizer extends NormalizerBase {
  /**
 * The interface or class that this Normalizer supports.
 *
 * @var string
 */
  protected $supportedInterfaceOrClass = 'Drupal\Core\TypedData\TypedDataInterface';
  /**
 * {@inheritdoc}
 */
  public function normalize($object, $format = NULL, array $context = array()) {
    $value = $object->getValue();
    if (isset($value[0]) && isset($value[0]['value'])) {
      $value = $value[0]['value'];
    }
    return $value;
  }
}

and

2. Custom Node Entity Normalizer

example_normalizer.services.yml

services:
  example_normalizer.node_entity:
    class: Drupal\example_normalizer\Normalizer\NodeEntityNormalizer
    arguments: ['@entity.manager']
    tags:
    - { name: normalizer, priority: 8 }

src/Normalizer/NodeEntityNormalizer.php

<?php
namespace Drupal\example_normalizer\Normalizer;
use Drupal\serialization\Normalizer\ContentEntityNormalizer;
use Drupal\Core\Datetime\DrupalDateTime;
/**
 * Converts the Drupal entity object structures to a normalized array.
 */
class NodeEntityNormalizer extends ContentEntityNormalizer {
  /**
 * The interface or class that this Normalizer supports.
 *
 * @var string
 */
  protected $supportedInterfaceOrClass = 'Drupal\node\NodeInterface';
  /**
 * {@inheritdoc}
 */
  public function normalize($entity, $format = NULL, array $context = array()) {
    // Similar logic as above
  }
}

However, in both cases, when I clear the cache I am getting the error

PHP Fatal error:  Uncaught Error: Class "Drupal\example_normalizer\Normalizer\NodeEntityNormalizer" not found in /var/www/html/web/core/lib/Drupal/Component/DependencyInjection/Container.php:262

What am I missing in my module that this is not getting picked up?

I'd like to be able to make a call like

$serializer = \Drupal::service('serializer')
$custom_json = $serializer->serialize($entity, 'json', ['plugin_id' => 'my_custom_normalizer']

Answer 1

JSON normalization is not declared in services.yml. Instead, you want to use MyModuleServiceProvider.php to override the core class.

This is an example from my site overriding FieldItemNormalizer:

<?php
    
namespace Drupal\my_module;

use Drupal\Core\DependencyInjection\ServiceProviderBase;
use Drupal\Core\DependencyInjection\ServiceProviderInterface;
use Drupal\Core\DependencyInjection\ContainerBuilder;
use Symfony\Component\DependencyInjection\Reference;

class MyModuleServiceProvider extends ServiceProviderBase implements ServiceProviderInterface {

  /**
   * {@inheritDoc}
   */
  public function alter(ContainerBuilder $container): void {
    $jsonapi_definition = $container->getDefinition('serializer.normalizer.field_item.jsonapi');
    $jsonapi_definition->setClass('Drupal\my_module\Normalizer\MyModuleFieldItemNormalizer');
}

Here's a general guide to overriding core services.