Exclude certain products from shopping cart directory

site.php

<?php

Am_Di::getInstance()->productTable->customFields()->add(new Am_CustomFieldCheckbox('cart_exclude', 'Exclude from Shopping Cart'));

Am_Di::getInstance()->hook->add('cartGetProductsQuery', function(Am_Event $e) {
     /* @var $q Am_Query */
    $q = $e->getQuery();
    $q->leftJoin('?_data', 'd', "d.`table` = 'product' AND d.`key` = 'cart_exclude' AND d.`id` = p.product_id");
    $q->addWhere('d.`value` IS NULL OR d.`value`<>1');
});