product code in pdf invoice

$productClass = hikashop_get('class.product');
$productData = $productClass->get($product->product_id);
if($productData->product_quantity>0) echo 'Product on stock';

$productClass = hikashop_get('class.product');
$productData = $productClass->get($product->product_id);
if($productData->product_parent_id){
 $parentProductData = $productClass->get($product->product_parent_id);
 $productData->product_manufacturer_id = $parentProductData->product_manufacturer_id;
}
$categoryClass = hikashop_get('class.category');
$category = $categoryClass->get($productData->product_manufacturer_id);
echo $category->category_name;