Symfony 4 implement REST API - php

Question

I'm implementing a simple REST API in my Symfony 4 project. When I test the getArticle() function with Postman this is the error:
The controller must return a response (Object(FOS\RestBundle\View\View) given).
With a var_dump($articles) content is displayed as expected so I guess the problem could be the FOSRestBundle but I don't know other ways to do this job.
class ArticleController extends FOSRestController
{
/**
* Retrieves an Article resource
* #Rest\Get("/articles/{id}")
*/
public function getArticle(int $articleId): View
{
$em = $this->getDoctrine()->getManager();
$article = $em->getRepository(Article::class)->findBy(array('id' => $articleId));
// In case our GET was a success we need to return a 200 HTTP OK response with the request object
return View::create($article, Response::HTTP_OK);
}
}

Answer 1

Define a view response listener in your config/packages/fos_rest.yaml. For details why and what it does read the FOSRest documentation here.
fos_rest:
view:
view_response_listener: true
Also add this to your fos_rest.yaml to select your output format -> here json
fos_rest:
[...]
format_listener:
rules:
- { path: ^/, prefer_extension: true, fallback_format: json, priorities: [ json ] }

Answer 2

I've found a solution by myself returning a HttpFoundation\Response, it might be helpful to someone.
/**
* Lists all Articles.
* #FOSRest\Get("/articles")
*/
public function getArticles(Request $request): Response
{
$em = $this->getDoctrine()->getManager();
$articles = $em->getRepository(Article::class)->findAll();
return new Response($this->json($articles), Response::HTTP_OK);
}