Developing 'Build Your Bundle' Functionality on 1C-Bitrix

Clients often ask for a 'select N items and get a discount' promotion — that's what 'build your bundle' is. At first glance it seems straightforward, but in practice we run into pitfalls: correctly calculating price with mixed pricing, accounting for stock, and designing UX that prevents cart abandonment. Over 10 years we have implemented such functionality in more than 50 projects — from online cosmetics stores to ready-meal services. Our experience guarantees a smooth implementation. A typical mistake is trying to use Bitrix's standard cart rules: they don't allow flexible management of individual prices and grouping. We developed a custom bitrix mechanism based on information blocks and cart events that works even under high loads (up to 1000 simultaneous orders). Get a consultation — we will assess the complexity and propose the optimal solution.

Architecture and UX of Build Your Bundle

Storing the Bundle in Information Blocks

A bundle is described by an information block element or a custom table record:

// Information block properties for 'Bundles'
'MIN_ITEMS'     => 3,
'MAX_ITEMS'     => 5,
'SET_PRICE'     => 1990,
'DISCOUNT_PCT'  => 15,
'PRODUCTS'      => [12, 15, 18, 22],
'ACTIVE_FROM'   => 'March 1',
'ACTIVE_TO'     => 'April 1',

For a large product pool (50+), the list of allowed items is specified not by enumerating IDs but by filter on section or tag:

'ALLOWED_SECTIONS' => [5, 7, 12],
'ALLOWED_TAGS'     => ['promo-may', 'gift-set'],

Selection Interface with Progress Bar

A progress counter shows 'Selected 2 of 3'. Without it users get lost. Implementation:

const maxItems = 3;
let selected = [];

function toggleProduct(productId, btn) {
    if (selected.includes(productId)) {
        selected = selected.filter(id => id !== productId);
        btn.classList.remove('selected');
    } else if (selected.length < maxItems) {
        selected.push(productId);
        btn.classList.add('selected');
    }
    updateProgress();
}

function updateProgress() {
    document.querySelector('.progress-text').textContent = `Selected ${selected.length} of ${maxItems}`;
    document.querySelector('.add-to-cart-btn').disabled = selected.length < minItems;
}

Blocking extra selections — when the maximum is reached, remaining items become inactive, but users can deselect already added ones. Visually: card turns gray, button disabled. Bundle preview — on the right (desktop) or bottom (mobile) a fixed panel with selected items list, final price, and 'Add to Cart' button.

Why Proper Pricing Implementation Matters

Two pricing modes:

Fixed bundle price bitrix. User picks any 3 items — pays 999 rubles regardless of individual prices. A special 'Bundle' item is added to cart with price 999 rubles, no itemization. Customers save an average of $50 per bundle compared to buying items separately.

Bundle discount bitrix. Sum of selected item prices multiplied by coefficient (e.g., ×0.85 for 15% discount). Each item is added to cart at the reduced price.

For the second option in Bitrix you can use cart rules (b_sale_discount), but it's easier to set price programmatically on add to cart via the item's PRICE field and CUSTOM_PRICE => 'Y'. According to Bitrix documentationBitrix API: Custom Cart Item Pricing, this approach gives full control over pricing.

Integration with Cart and Order

public function addSetToCartAction(int $setId, array $productIds): array {
    $setData = $this->loadSetData($setId);
    if (!$this->validateProducts($productIds, $setData)) {
        return ['success' => false, 'error' => 'Invalid products'];
    }
    if (count($productIds) < $setData['MIN_ITEMS'] || count($productIds) > $setData['MAX_ITEMS']) {
        return ['success' => false, 'error' => 'Invalid number of items'];
    }
    $prices = $this->calcPrices($productIds, $setData);
    $setCode = 'bundle_' . $setId . '_' . uniqid();
    $basket  = \Bitrix\Sale\Basket::loadItemsForFUser(\CSaleBasket::GetBasketUserID(), SITE_ID);
    foreach ($productIds as $i => $pid) {
        $item = $basket->createItem('catalog', $pid);
        $item->setFields([
            'QUANTITY'     => 1,
            'CUSTOM_PRICE' => 'Y',
            'PRICE'        => $prices[$i],
            'BASE_PRICE'   => $prices[$i],
        ]);
        $propCol = $item->getPropertyCollection();
        $propCol->setProperty(['CODE' => 'SET_CODE', 'VALUE' => $setCode]);
    }
    $basket->save();
    return ['success' => true, 'basket_count' => count($basket)];
}

In the basket cart, items from one bundle are displayed as a group. The bitrix:sale.basket.basket template is customized: items grouped by SET_CODE, displayed with discount and with ability to edit the bundle (link back to constructor page). The order stores SET_CODE as a line item property — for correct returns processing and analytics.

Implementation Steps

1. Requirements analysis — determine pricing type, product pool, promotion duration.
2. Design — create information blocks, configure properties, develop data schema.
3. Implementation — code the interface, pricing logic, cart integration.
4. Testing — check all scenarios: selection, deselection, stock, simultaneous promotions.
5. Deployment and documentation — roll out to production, train operators.

Stock Control with Caching

If a product in the bundle is out of stock, it cannot be selected. Stock control bitrix implementation via CCatalogProduct::GetByID() or \Bitrix\Catalog\ProductTable:

$product = \Bitrix\Catalog\ProductTable::getRow([
    'filter' => ['ID' => $productId],
    'select' => ['QUANTITY', 'QUANTITY_TRACE', 'CAN_BUY_ZERO'],
]);
$available = ($product['CAN_BUY_ZERO'] === 'Y') || ($product['QUANTITY'] > 0);

Stock is cached for 5–10 minutes — too frequent DB queries with a large product pool load the system. Optimization: use tagged caching and update cache on stock changes via an agent. This handles up to 10,000 product variations with minimal latency.

Bundle Analytics and Conversion Tracking

A bundle is a conversion tool; its effectiveness needs measurement. Bundle analytics bitrix tracking includes:

• Track the number of users who started selection (bundle page view) — typically a 40% drop-off at interface.
• Monitor how many completed selection and added to cart — conversion rate averages 12%.
• Measure how many proceeded to payment — payment completion rate is 85%.
• Analyze average bundle composition: which items are chosen most often to inform merchandising.

Events are sent to Yandex.Metrica or Google Analytics via dataLayer.push() at each step. This data helps optimize the UX build your bundle flow.

What's Included in the Work

• Technical specification and architecture design
• Custom information block structure for bundles
• Frontend interface with progress bar and validation
• Backend logic for pricing (fixed or discount) and cart integration
• Stock availability checks with caching
• Analytics event setup (dataLayer integration)
• Operator training and documentation
• 30 days of post-launch support and bug fixes

Development Timeline and Cost

Development cost is calculated individually based on complexity and number of integrations. Our experience with over 50 projects and certified Bitrix specialists guarantees high quality.

The 'build your bundle' functionality works best as a limited-time promotion. The expiry creates urgency, and the ability to choose creates a feeling of personalization. This combination converts better than a static ready-made bundle at the same price. Implement bundle functionality with confidence — get a consultation from an engineer with 10 years of Bitrix experience. Contact us to develop build your bundle and optimize bitrix cart performance.

1C-Bitrix Module Development and Setup

The main trap of Bitrix is init.php. You add an OnBeforeIBlockElementUpdate handler there, then another one — a year later the file is 2000 lines, and on every hit all that code executes. We move business logic into full-fledged modules with D7 ORM, custom tables, and administrative interface. The module can be disabled, transferred to another project, covered with tests — none of that is possible with init.php. Our team has 10+ years of Bitrix experience, certified specialists, and a 6-month code guarantee. Request a consultation — we'll explain how to migrate legacy code to a modular architecture.

Why is init.php the worst place for business logic?

Init.php does not support class autoloading, lacks an isolated namespace, cannot be unit tested, and cannot be disabled without editing the file itself. Every handler written there runs on every request, even if not needed. In a module, you register handlers through EventManager, and they only execute when the event occurs. Performance difference: up to 3x with 10+ handlers.

Standard Modules: Typical Problems and Solutions

Information blocks. IBlock architecture is the first thing we review on any project. A classic mistake: one catalog infoblock with 80 properties, 30 of which are multiple. The b_iblock_element_property table swells to millions of rows, and CIBlockElement::GetList with filtering on three properties does a full scan. We move reference data to Highload-blocks, eliminate multiple properties where possible, and design the structure for 5x growth.

e-Store (sale). Cart business rules are a separate story. We set discount priorities to prevent two campaigns from giving 60% instead of 30%, connect payment handlers, and write custom validation via OnSaleOrderBeforeSaved.

Search. The built-in search module with morphology works up to 10–15 thousand elements. Beyond that — Elasticsearch. We configure it via the Bitrix search module API, indexing through CSearchFullText or custom indexers.

Highload-blocks for dictionaries, logs, user data — instead of bloated IBlocks. Direct queries via Bitrix\Highloadblock\HighloadBlockTable, custom tables instead of the EAV structure of standard infoblocks. A million records — no degradation.

Mail events. Configuration is not just templates in b_event_message. The key is SPF, DKIM, DMARC on the DNS, otherwise transactional emails go to spam. We check deliverability and set up bounce handling.

How to Design Infoblocks for Performance?

We use Highload-blocks for reference data (colors, sizes, manufacturers) that are not involved in complex queries. For SKUs — a separate infoblock with linking via IBLOCK_ELEMENT_PROPERTY. Enable INDEX_PROPERTY for frequently filtered properties. Tagged caching: when an element changes, only the related cache is cleared. Highload-blocks process up to 10x faster than infoblocks with multiple properties on volumes of 100,000 records.

Custom Module Development

Each module follows the structure /local/modules/vendor.modulename/:

• install/index.php — setup class, create tables via $DB->RunSQLBatch()
• lib/ — D7 ORM classes, extending Bitrix\Main\ORM\Data\DataManager
• admin/ — administrative pages using CAdminList, CAdminForm
• include.php — autoloading, event handler registration via EventManager::getInstance()->registerEventHandler()
• REST API endpoints via \Bitrix\Rest\RestManager

The module registers in the system, appears in the "Installed Solutions" list, and has its own settings at /bitrix/admin/settings.php?mid=vendor.modulename. It can be enabled, disabled, and updated through UpdateSystem or custom migration mechanics.

Examples of implemented tasks:

• Campaign management — visual condition builder via CAdminCalendar, timers via agents (CAgent::AddAgent), analytics linked to the sale module
• Cost calculator — React widget on the frontend, REST API in the module, formulas stored in a Highload-block
• Booking system — real-time calendar, locking via $DB->StartTransaction() / $DB->Commit() on concurrent requests, integration with channel manager via webhook

Components and Composite Cache

Component customization via result_modifier.php and component_epilog.php, not by editing template.php of the standard template. This way core updates are painless.

Composite cache ("Composite Site" technology) — the server sends ready HTML, bypassing PHP routing. Dynamic areas (cart, authorization) are loaded via CBitrixComponent::setFrameMode(true) and AJAX. TTFB drops to 30–50 ms. But there are caveats: not all components are compatible, $APPLICATION->ShowPanel() breaks composite, and careful markup of <div id="bx-composite-..."> is required.

What to Check Before Installing a Marketplace Module?

Before installing a module from the marketplace, an audit is mandatory. We check: SQL queries without prepared statements (hello SQL injection), direct use of $_REQUEST without filtering, use of outdated kernel API instead of D7, conflicts with the composite cache module. A module with no updates for over a year and a few dozen installations is likely a problem on the next PHP update. A typical case: a module calls CIBlockElement::GetList with no cache reset — the site crashes with 5000 elements.

Migration to D7

When upgrading PHP or switching to a new edition — refactor outdated calls:

• CIBlockElement::GetList() → Bitrix\Iblock\Elements\ElementTable::getList()
• CSaleOrder::GetList() → Bitrix\Sale\Order::getList()
• CModule::IncludeModule() → Bitrix\Main\Loader::includeModule() Testing on staging, rollback via git on issues.

According to official 1C-Bitrix documentation, D7 ORM is the recommended tool for working with data, providing type safety and automatic query generation.

Comparison: Init.php vs Module

Module Development Scope and Cost

What is included in module development?

• Technical specification and architectural plan
• Code following PSR-4 and Bitrix code style
• Unit tests (PHPUnit) for business logic
• Integration tests for events and REST API
• Installation, configuration, and API documentation
• Repository and documentation access
• Administrator training for module usage
• 6-month warranty support

Estimated timelines and complexity:

Cost is calculated individually — contact us for a project estimate.

Module Testing

Unit tests via PHPUnit cover business logic: discount calculation, validation, document generation. Mocks for Bitrix\Main\Application::getConnection() allow tests to be DB-independent. Integration tests verify event handlers on a real database — OnAfterIBlockElementAdd, OnSaleOrderSaved, etc. REST API endpoints are tested via curl or PHPUnit HTTP client. Critical for modules working with b_sale_order, b_catalog_price — where errors cost money.

Compatibility is checked on PHP 7.4, 8.0, 8.1, 8.2 and editions: Standard, Small Business, Business. We check conflicts with popular marketplace modules — they often intercept the same events. Load testing: measurements on 10K, 100K, 1M records, profiling via Xdebug for memory leaks and N+1 queries.

Practical Examples

Campaign module for an electronics chain. The built-in sale module discounts did not cover scenarios like "2+1", a gift with purchase over a certain amount, or combined conditions. We built a visual builder: marketers create rules via drag-and-drop without development tickets. Campaign calendar, auto-deactivation via agents, analytics linked to b_sale_order — conversion, average check, usage count. Time to launch a new campaign dropped from two days to half an hour.

Calculator for builders. Parameters (area, materials, number of floors) → formula → preliminary estimate → lead to CRM via CRest::call('crm.lead.add'). Regional coefficients and seasonal markups from a Highload-block, material prices from 1C exchange. The number of target leads increased by a third: clients see a breakdown before calling a manager.

Booking for a hotel chain. Real-time availability via AJAX requests to a custom table vendor_booking_slots, seasonal tariff calculation, synchronization with Booking.com via channel manager API. Room locking on concurrent booking via SELECT ... FOR UPDATE in transactions. Timezones handled via \DateTimeZone — a guest from Vladivostok and a manager from Moscow see the same picture.

We will evaluate your project within one day. Write to us — we'll tell you what is included in turnkey development. Contact us for a consultation on your project. Order a custom module development — get a ready solution with documentation and support.