OpenApiFactory.php

<?php

declare(strict_types=1);

namespace App\OpenApi;

use ApiPlatform\Core\OpenApi\Factory\OpenApiFactory as ApiPlatformOpenApiFactory;
use ApiPlatform\Core\OpenApi\Factory\OpenApiFactoryInterface;
use ApiPlatform\Core\OpenApi\OpenApi;
use ApiPlatform\Core\OpenApi\Model;
use Symfony\Component\DependencyInjection\Attribute\AsDecorator;

#[AsDecorator(decorates: ApiPlatformOpenApiFactory::class)]
final class OpenApiFactory implements OpenApiFactoryInterface
{
    public function __construct(private OpenApiFactoryInterface $decorated) {}

    public function __invoke(array $context = []): OpenApi
    {
        $openApi = $this->decorated->__invoke($context);

        $pathItem = $openApi->getPaths()->getPath('/api/grumpy_pizzas/{id}');
        $operation = $pathItem->getGet();

        $openApi->getPaths()->addPath('/api/grumpy_pizzas/{id}', $pathItem->withGet(
            $operation->withParameters(array_merge(
                $operation->getParameters(),
                [new Model\Parameter('fields', 'query', 'Fields to remove of the output')]
            ))
        ));

        return $openApi;
    }
}