Если в корзине, то.. В корзине..) - JoomShopping

       $session =JFactory::getSession();
       $back_value = array('pid'=>$product_id, 'attr'=>$jshop_attr_id, 'freeattr'=>$freeattribut,'qty'=>$quantity);
       $session->set('product_back_value', $back_value);

        $dannie = $session->get('product_back_value' ,$back_value);

if (!$cart->add($product_id, $quantity, $jshop_attr_id, $freeattribut)){
            if ($ajax){
                print getMessageJson();
                die();
            }
            $session =JFactory::getSession();
            $back_value = array('pid'=>$product_id, 'attr'=>$jshop_attr_id, 'freeattr'=>$freeattribut,'qty'=>$quantity);
            $session->set('product_back_value', $back_value);
            $this->setRedirect(SEFLink('index.php?option=com_jshopping&controller=product&task=view&category_id='.$category_id.'&product_id='.$product_id,1,1));
            return 0;
        }

$cart = JModelLegacy::getInstance('cart', 'jshop');
$cart->load();
print_r($cart->products);

$cart = JModelLegacy::getInstance('cart', 'jshop');
$cart->load();
$prover = array($cart->products[1][product_id], $cart->products[2][product_id], $cart->products[3][product_id], $cart->products[4][product_id]);
if (in_array($this->product->product_id, $prover)) {
    echo "в корзине";
}
else {
echo "в корзину";
}

$(".click_buy").parent().prepend("<a href='/im/shop/cart/add.html?category_id=1&amp;product_id=8' class=in_cart'>в корзине</a>");
$(".click_buy.button_buy").remove();

$inCart = false;
foreach ($cart->products as $prod) {
	if ($this->product->product_id == $prod['product_id']) {
		$inCart = true;
		break;
	}
}
if ($inCart) {
	echo "в корзине";
} else {
	...
}