Custom response in custom class

Hey i’ve been trying slim for several days now i am able to make simple API like so

$app->get('/articles/getcategories', function (Request $request, Response $response, array $args) {
(new Category) -> getCategories($response);

one problem is when i want to send a custom response code to my end point from my class, in this case Category class it doesn’t work, i was able to send a response using this method :

$response -> getBody() -> write(json_encode($this -> makeObject(704, 'Something went wrong!')));

But when i look at the documentation :

$newResponse = $response->withStatus(302);
$data = array('name' => 'Rob', 'age' => 40);
$newResponse = $oldResponse->withJson($data, 201);

or like this :

return $response->withStatus(xxx);

it doesnt work, this is my custom class

 public function getCategories($response){

    $dbconn = (new db())->connect();
        //start db connection
    try {
        $stmt = $dbconn->prepare("SELECT category_id, category_name, category_description, category_type FROM article_category");

        $categories = $stmt->fetchAll(PDO::FETCH_ASSOC);

    } catch (PDOException $e){
        $response -> getBody() -> write(json_encode($this -> makeObject(704, 'Something went wrong!')));


What am i doing wrong here?

You should return the $response object (and use the withJson method).

return $response;

The $response object is immutable.

You need to return the $response object from getCategories() and then return that from your action.