I’m trying to extend Serialization to get the JSON Field module to return a JSON object instead of stringified JSON.

Goal: When I access an entity that contains a JSON field using JSON:API, I want a JSON object for the field value (currently, the stringified JSON is returned).

I think what I need to do is to extend one of the core normalizers and use it to add a json_decode() step.

There is some documentation on how Serializer handles entities but it is out-of-date (last updated in 2017 before JSON:API was part of core, and the current code looks nothing like what is shown.)

I tried extending FieldNormalizer in /json_field/src/Normalizer/JsonFieldNormalizer.php.
However, I’m not confident that this is the correct approach, as there is also a FieldItemNormalizer and TypedDataNormalizer. To change how a field is output in JSON:API, which class should I extend?

<?php  namespace Drupaljson_fieldNormalizer;  use DrupalCoreFieldFieldDefinitionInterface; use Drupaljson_fieldPluginFieldFieldTypeNativeJSONItem; use DrupaljsonapiJsonApiResourceResourceObject; use DrupaljsonapiNormalizerFieldNormalizer; use DrupaljsonapiNormalizerValueCacheableNormalization; use DrupaljsonapiResourceTypeResourceType;  class JsonFieldNormalizer extends FieldNormalizer {    /**    * {@inheritdoc}    */   protected $supportedInterfaceOrClass = NativeJSONItem::class;    /**    * {@inheritdoc}    */   public function normalize($field, $format = NULL, array $context = []) {     $field_name = $field->getName();     Drupal::logger('json_field')->info("Field has name $field_name");     assert($field instanceof NativeJSONItem);     /** @var DrupalCoreFieldFieldItemListInterface $field */ $normalized_items = $this->normalizeFieldItems($field, $format, $context);     assert($context['resource_object'] instanceof ResourceObject);     return $context['resource_object']->getResourceType()->getFieldByInternalName($field->getName())->hasOne()       ? array_shift($normalized_items) ?: CacheableNormalization::permanent(NULL)       : CacheableNormalization::aggregate($normalized_items);   } 

And I added the class to json_field.services.yml:

services:   json_field.views:     class: Drupaljson_fieldJSONViews   json_field.normalizer.field.json_field:     class: Drupaljson_fieldNormalizerJsonFieldNormalizer     tags:       - { name: normalizer, priority: 1 } 

However, after rebuilding the cache and accessing some JSON fields via JSON:API, I don’t see anything in the logs, so it seems like the class is not being picked up.