I have a custom Prestashop theme, running on Prestashop 1.6.1.9 and the product sort (Sort by Lowest Price first) doesn't take into account the specific prices (discounts). It uses the Retail price with Taxes instead.
To better explain, this is how the filter currently works:
Product 1 - 11$ | Product 2 - 15$ | Product 3 - 25$ | Product 4 - 16$ (35$ before the discount)
Product 4 should be above product 3, but the filter takes the price before discount into account, not the final price with discount.
How can I sort by final price?
This is the SQL query in Category.php:
$sql = 'SELECT p.*, product_shop.*, stock.out_of_stock, IFNULL(stock.quantity, 0) AS quantity'.(Combination::isFeatureActive() ? ', IFNULL(product_attribute_shop.id_product_attribute, 0) AS id_product_attribute,
product_attribute_shop.minimal_quantity AS product_attribute_minimal_quantity' : '').', pl.`description`, pl.`description_short`, pl.`available_now`,
pl.`available_later`, pl.`link_rewrite`, pl.`meta_description`, pl.`meta_keywords`, pl.`meta_title`, pl.`name`, image_shop.`id_image` id_image,
il.`legend` as legend, m.`name` AS manufacturer_name, cl.`name` AS category_default,
DATEDIFF(product_shop.`date_add`, DATE_SUB("'.date('Y-m-d').' 00:00:00",
INTERVAL '.(int)$nb_days_new_product.' DAY)) > 0 AS new, **product_shop.price AS orderprice**
FROM `'._DB_PREFIX_.'category_product` cp
LEFT JOIN `'._DB_PREFIX_.'product` p
ON p.`id_product` = cp.`id_product`
'.Shop::addSqlAssociation('product', 'p').
(Combination::isFeatureActive() ? ' LEFT JOIN `'._DB_PREFIX_.'product_attribute_shop` product_attribute_shop
ON (p.`id_product` = product_attribute_shop.`id_product` AND product_attribute_shop.`default_on` = 1 AND product_attribute_shop.id_shop='.(int)$context->shop->id.')':'').'
'.Product::sqlStock('p', 0).'
LEFT JOIN `'._DB_PREFIX_.'category_lang` cl
ON (product_shop.`id_category_default` = cl.`id_category`
AND cl.`id_lang` = '.(int)$id_lang.Shop::addSqlRestrictionOnLang('cl').')
LEFT JOIN `'._DB_PREFIX_.'product_lang` pl
ON (p.`id_product` = pl.`id_product`
AND pl.`id_lang` = '.(int)$id_lang.Shop::addSqlRestrictionOnLang('pl').')
LEFT JOIN `'._DB_PREFIX_.'image_shop` image_shop
ON (image_shop.`id_product` = p.`id_product` AND image_shop.cover=1 AND image_shop.id_shop='.(int)$context->shop->id.')
LEFT JOIN `'._DB_PREFIX_.'image_lang` il
ON (image_shop.`id_image` = il.`id_image`
AND il.`id_lang` = '.(int)$id_lang.')
LEFT JOIN `'._DB_PREFIX_.'manufacturer` m
ON m.`id_manufacturer` = p.`id_manufacturer`
WHERE product_shop.`id_shop` = '.(int)$context->shop->id.'
AND cp.`id_category` = '.(int)$this->id
.($active ? ' AND product_shop.`active` = 1' : '')
.($front ? ' AND product_shop.`visibility` IN ("both", "catalog")' : '')
.($id_supplier ? ' AND p.id_supplier = '.(int)$id_supplier : '');
if ($random === true) {
$sql .= ' ORDER BY RAND() LIMIT '.(int)$random_number_products;
} else {
$sql .= ' ORDER BY '.(!empty($order_by_prefix) ? $order_by_prefix.'.' : '').'`'.bqSQL($order_by).'` '.pSQL($order_way).'
LIMIT '.(((int)$p - 1) * (int)$n).','.(int)$n;
}
The products sorting on category page is handled by the getProducts() function in Category.php class.
There are 2 parameters in this function (i.e. $order_by, $order_way) that handle product sorting. There is a query in this function for fetching the products and there is a column selected as well (i.e. product_shop.price AS orderprice). You can change the column name here to change the sort order logic.