Serialize data from database - serialization

Question

I have problem with my Symfony rest API. I have this controller:
<?php
namespace App\Controller;
use App\Entity\Post;
use App\Service\ErrorDecoratorService;
use App\Service\PostService;
use Symfony\Bundle\FrameworkBundle\Controller\AbstractController;
use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\Routing\Annotation\Route;
use Symfony\Component\HttpFoundation\JsonResponse;
use Symfony\Component\Serializer\SerializerInterface;
class PostController extends AbstractController
{
private $postService;
private $errorDecoratorService;
public function __construct(PostService $postService, ErrorDecoratorService $errorDecoratorService)
{
$this->postService = $postService;
$this->errorDecoratorService = $errorDecoratorService;
}
/**
* #Route("/post/{postId}", methods={"GET"})
* #param $postId
* #param SerializerInterface $serializer
* #return JsonResponse
*/
public function getPost($postId, SerializerInterface $serializer)
{
$result = $this->postService->getPost($postId);
if ($result instanceof Post) {
$data = $serializer->serialize($result,'json');
$status = JsonResponse::HTTP_OK;
} else {
$status = JsonResponse::HTTP_NOT_FOUND;
$data = $this->errorDecoratorService->decorateError($status, $result);
}
return new JsonResponse($data, $status);
}
}
When I have from database serialize to JSON format, then I receive this error:
Could not normalize object of type App\Entity\Post, no supporting
normalizer found. (500 Internal Server Error)
It's my entity
<?php
namespace App\Entity;
use Doctrine\ORM\Mapping as ORM;
use Symfony\Component\Validator\Constraints as Assert;
/**
* #ORM\Entity(repositoryClass="App\Repository\PostRepository")
*/
class Post
{
/**
* #ORM\Id()
* #ORM\GeneratedValue()
* #ORM\Column(type="integer")
*/
private $id;
/**
* #ORM\Column(type="string", length=255)
* #Assert\NotBlank()
*/
private $title;
/**
* #ORM\Column(type="string", length=255)
* #Assert\NotBlank()
*/
private $content;
/**
* #ORM\Column(type="string", length=255)
* #Assert\NotBlank()
*/
private $author;
public function getId(): ?int
{
return $this->id;
}
public function getTitle(): ?string
{
return $this->title;
}
public function setTitle(string $title): self
{
$this->title = $title;
return $this;
}
public function getContent(): ?string
{
return $this->content;
}
public function setContent(string $content): self
{
$this->content = $content;
return $this;
}
public function getAuthor(): ?string
{
return $this->author;
}
public function setAuthor(string $author): self
{
$this->author = $author;
return $this;
}
}
Where is my mistake? I have tried Symfony Serializer, JMS Serializer but I still get the same error.

Answer 1

Once you enable the Normalizer the Serializer will produce a json encoded string with this line:
$data = $serializer->serialize($result,'json');
// "{\"id\":1,\"title\":\"qwerty\",\"content\":\"Lorem ipsum sit dolor amet\",\"author\":\"Pawel\"}"
The JsonResponse construct json encodes the first parameter, usually an array or object, but in your case just a string. You need to either decode the string when you pass it to the constructor, or preferably use the JsonResponse::fromJsonString() method.
Should work:
return new JsonResponse(json_decode($data), $status);
Preferred method:
return new JsonResponse::fromJsonString($data, $status);
https://symfony.com/doc/current/components/http_foundation.html#creating-a-json-response