Slim 3 no response - php

Question

So this is what i had first:
$app->get('/object/{id:[0-9]+}', function ($request, $response, $args) {
$id = (int)$args['id'];
$this->logger->addInfo('Get Object', array('id' => $id));
$mapper = new ObjectMapper($this->db);
$object = $mapper->getObjectById($id);
return $response->withJson((array)$object);
});
It worked well and outputted the whole DB Object as a nice JSON String.
Now i reorganized everything a little on MVC basis and this is whats left:
$app->get('/object/{id:[0-9]+}', ObjectController::class . ':show')->setName('object.show');
It also works, but i don't get any Output. If i put a var_dump before the DB Object is there, but how do i get a JSON String from that again?
Here comes the Controller
<?php
namespace Mycomp\Controllers\Object;
use \Psr\Http\Message\ServerRequestInterface as Request;
use \Psr\Http\Message\ResponseInterface as Response;
use Interop\Container\ContainerInterface;
use Mycomp\Models\Object;
class ObjectController
{
protected $validator;
protected $db;
protected $auth;
protected $fractal;
public function __construct(ContainerInterface $container)
{
$this->db = $container->get('db');
$this->logger = $container->get('logger');
}
public function show(Request $request, Response $response, array $args)
{
$id = (int)$args['id'];
$this->logger->addInfo('Get Object', array('id' => $id));
$object = new Object($this->db);
return $object->getObjectById($id);
}
}

Answer 1

As Nima said in comment, you need to return Response object
public function show(Request $request, Response $response, array $args)
...
return $response->withJson($object->getObjectById($id));
}

Answer 2

In order for Slim to send HTTP response to client, route callback must return some data that Slim understands. That type of data, according to Slim documentation is a PSR 7 Response object.
This is important, because what the route callback returns will not necessarily be sent to client exactly as is . It might be used by middlewares to teak the response before sending it to the client.
the $response object, injected by Slim into your route callbacks is used for that purpose. Slim also provides some helper methods like 'withJson` to generate a proper (PSR 7) JSON response with proper HTTP headers.
So as I said in comment, you need to return response object
public function show(Request $request, Response $response, array $args)
// Prepare what you want to return and
// Encode output data as JSON and return a proper response using withJson method
return $response->withJson($object->getObjectById($id));
}