Cacheability metadata not bubbled up for computed fields in GraphQL responses

[rafatwork]

It looks like cacheability metadata for computed fields are not bubbled up in GraphQL responses.
This is a similar issue as https://www.drupal.org/node/3423720 (but then for GraphQL responses).

[klaasvw]

I had a similar problem, where I had a computed field that had to return a Url to another entity that was referencing the entity.

In the end the solution was making sure that the graphql field producer plugins use addCacheableDependency on the FieldContext passed to the resolve method.

In my case I had to use entity_reference as the field type for the computed field (instead of uri). Because we're using the graphql_compose module for the schema I used the field_entity_reference producer plugin. This adds the referencing entity as a cacheable dependency, thus making sure the cacheability metadata is bubbled up.

Example from the SchemaExtension plugin:

public function registerResolvers(ResolverRegistryInterface $registry): void {
 // ...
  $registry->addFieldResolver(
      $bundle->getTypeSdl(),
      'your_custom_field',
      $builder->compose(
        // Make sure the referenced entities are added to the
        // cacheability metadata.
        $builder->produce('field_entity_reference')
          ->map('entity', $builder->fromParent())
          ->map('field', $builder->fromValue('your_custom_field'))
          ->map('types', $builder->fromValue(['node'])),
        $builder->produce('seek')
          ->map('input', $builder->fromParent())
          ->map('position', $builder->fromValue(0)),
        $builder->produce('entity_url')
          ->map('entity', $builder->fromParent()),
        $builder->callback(fn (?Url $url) => $url ? $url->toString() : NULL)
      )
    );
  // ...
}