public function addToCart(Disc $disc)
    {
        $getCart = $this->session->get('cart');

        if(isset($getCart[$disc->getId()]))
        {
            $getCart[$disc->getId()]['quantity']++;
        }
        else
        {
            $getCart[$disc->getId()] = array(
                'quantity' => 1,
                'title' => $disc->getTitle(),
                'price' => $disc->getPrice(),
                'id' => $disc->getId(),
            );
        }
        $this->session->set('cart', $getCart);
 		return renderCart();
    }

public function renderCart()
{
	$getCart = $this->session->get('cart');
	return $this->render('discs/cart.html.twig', array(
            'cart' => $getCart
        ));
}