使用Doctrine（和Silex）将SQL数据作为数组返回

I'm using doctrine to fetch data from my MySQL database. This is all done in Silex. These are the lines of code that enable Doctrine for me.

$config = new \Doctrine\DBAL\Configuration();
$connParams = array(
    'driver'   => 'pdo_mysql',
    'dbname'   => 'webshop',
    'host'     => 'localhost',
    'user'     => 'root',
    'password' => '',
    'charset'  => 'utf8'
);
$conn = \Doctrine\DBAL\DriverManager::getConnection($connParams, $config);
$app['dbcon'] = $conn;

$app->get('/', function () use ($app){

    $user = new User($app['dbcon']);

    return $app['twig']->render('home.twig', [
        'content' => 'Home',
    ]);

})->bind('home');

And I'm trying to create a user class for login stuff etc. The user class looks like this:

<?php

namespace Models;

class User
{
    private $db;

    public function __construct($db)
    {
        $this->db = $db;
        $query = $this->db->prepare("SELECT * FROM users");
        $query->execute();

        $query = $query->fetchAll();

        foreach($query as $user){
            print_r($user);
        }

    }
}

Though, the following is the result:

Array ( [id] => 1 [username] => araguera [password] => password [salt] => ksjdfiwe98ru2w98h )

Why does it return as an array and not as an object? Because I want to be able to do something like "$query->username".