GraphQL 'create' mutation fields become null for resource names with certain suffixes when name_converter is SnakeCaseToCamelCaseNameConverter

[LuukOriginal]

API Platform version(s) affected: 4.1.23

Description
When using SnakeCaseToCamelCaseNameConverter (the default), GraphQL 'create' mutations for certain resources (as far as I noticed mainly if you have a model named like "TestModel" returns null for all fields (except fields like __typename or id) in the response payload.

For example:

• A simple resource named Test works as expected.
• A similar resource named TestItem (or other multi-word names) is creates the entry correctly in the database, but the GraphQL createTestItem mutation response contains only the id and __typename. All other scalar fields are null.

The database entry is correct and a subsequent get query for the same resource works fine. The issue is only with the mutation return data.

How to reproduce

1. Define two simple models/resources:

#[ApiResource(
    graphQlOperations: [new Mutation(name: 'create')]
)]
class Test extends Model
{
    protected $fillable = ['name'];
}

#[ApiResource(
    graphQlOperations: [new Mutation(name: 'create')]
)]
class TestItem extends Model
{
    protected $fillable = ['name'];
}

2. Use the default config:

// config/api-platform.php
return [
    'name_converter' => Symfony\Component\Serializer\NameConverter\SnakeCaseToCamelCaseNameConverter::class,
];

3. Run both mutations:

Successful:

mutation CREATE_TEST($input: createTestInput!) {
  createTest(input: $input) {
    test {
      id
      name
    }
  }
}

Unsuccessful:

mutation CREATE_TEST_ITEM($input: createTestItemInput!) {
  createTestItem(input: $input) {
    testItem {
      id
      name
    }
  }
}

Result:
For Test:

• DB contains entry
• All fields including name are specified correctly

For TestItem:

• DB contains entry
• All fields are null except id and __typename

If you change name_converter to null in api-platform.php, the response works as expected.

Possible Solution
It seems that the bug is caused by the SnakeCaseToCamelCaseNameConverter.
For resources with multi-word names (e.g. TestItem, TaskStatus), the generated GraphQL mutation response cannot map non-ID fields correctly.

Possible fixes:

• Ensure the name converter is applied only to attributes/properties.
• As a temporary workaround, setting 'name_converter' => null in config/api-platform.php fixes the issue, but is not always desirable .

Additional Context

• Logs confirm the model has correct attributes after creation (name is persisted).
  I used this code for that within a broken model:

protected static function booted()
  {
      parent::booted();

      static::created(function ($model) {
          info('TaskStatus::created attributes: ' . json_encode($model->getAttributes()));
          info('TaskStatus::created toArray: ' . json_encode($model->toArray()));
          info('TaskStatus::created class: ' . get_class($model));
      });
  }

• Queries for the resource work fine.
• Environment: Laravel 12.28.1, PHP 8.4.5.