block products sorted by online_only field

[phper]

hi all

i want to display the products defined as ( web Exclusive ), i try to get theme by ( online_only ) field in ( ps_product ) table , that's my request code in the php file of my modul :

$products = $category->getProducts(intval($params['cookie']->id_lang), 1,($nb ? $nb : 3), 'online_only', 'DESC');

but doesnt work exactly

plz help me to know what's wrong in my code ??

thank you for your replies.

Regards.