Separate Carts for Multi-Site 1C-Bitrix

We've encountered multi-site projects where retail and wholesale sites share a common catalog. The problem: by default, Bitrix's shopping cart is tied to the user, not the site. A customer adds items on the retail site, switches to wholesale, and sees the same cart. This is unacceptable when prices, delivery, and client type differ. In practice, this breaks reporting and confuses managers. With over 10 years of experience and 40+ multi-site projects completed, we've set up separate carts reliably. Here's how it's done, with typical costs starting at $500.

Why Does the Cart Become Shared?

The cart is stored in the b_sale_basket table. Key fields:

SELECT id, fuser_id, site_id, product_id, quantity, price, currency FROM b_sale_basket WHERE fuser_id = 12345; 

There is a SITE_ID field in the cart, and Bitrix uses it. The problem is that fuser_id (fusion user — anonymous user) is tied to the cookie BITRIX_SM_FUSER_ID, which is common across all subdomains unless configured otherwise. Quoting from the documentation: “The cart is attached to the fuser_id, which can be the same for different sites if they share the session domain.” This leads to mixing items.

Choosing a Separation Method

Method 1: Separate Domains Without Shared Cookies

The most reliable way, offering 100% isolation. If sites run on different domains (retail.shop.ru and wholesale.shop.ru) or different second-level domains, the fuser_id cookie is not passed automatically. Bitrix creates separate carts out of the box. This approach is best suited for separation: it eliminates influence from the adjacent site completely.

Check current configuration:

// /bitrix/php_interface/dbconn.php or .settings.php // Check SESSION_DOMAIN — if same for all sites, problem exists $_SESSION['BITRIX_SM_FUSER_ID']; // Same for all sites 

Method 2: Explicit SITE_ID Passed to Cart Component

The bitrix:sale.basket.basket component accepts a SITE_ID parameter. Ensure it is passed correctly:

$APPLICATION->IncludeComponent('bitrix:sale.basket.basket', '.default', [ 'SITE_ID' => SITE_ID, // Current site ID 'PRICE_VAT_SHOW_VALUE' => 'Y', // ... ]); 

Method 3: Programmatic Separation via Event

If the architecture does not allow domain separation, subscribe to the OnBeforeBasketItemAdd event and forcibly set SITE_ID:

// /local/php_interface/init.php AddEventHandler('sale', 'OnBeforeBasketItemAdd', 'SetBasketSiteId'); function SetBasketSiteId(&$arFields) { $currentSite = \Bitrix\Main\Context::getCurrent()->getSite(); $arFields['SITE_ID'] = $currentSite; return true; } 

The OnBeforeBasketItemAdd event is the entry point before data is written. We change SITE_ID to the current one before writing. This guarantees that the cart is tied to the site where the purchase is made.

Correctly Counting Items in the Cart

The cart counter in the header is a typical place where separate carts break visually: it shows the total quantity across all sites. Fix by explicitly filtering:

use Bitrix\Sale\Basket; use Bitrix\Main\Context; $basket = Basket::loadItemsForFUser( \CSaleBasket::GetBasketUserID(), Context::getCurrent()->getSite() // Pass current SITE_ID ); $itemCount = $basket->count(); 

Typical Errors and Checklist