Custom Discount Logic Development for 1C-Bitrix

Custom Discount Logic Development for 1C-Bitrix

The standard Bitrix discount builder covers most typical scenarios. But when you need a discount that depends on an external CRM, order history for the quarter, competitor stock or time of day – the standard tools run out. That's when custom logic is written. We handle the audit of your system, prototyping, development and debugging. Get a consultation – we'll evaluate your project in one day. Our experience: over 50 implementations of custom discount logic on the 1C-Bitrix platform.

Why Standard Discounts Are Not Enough

Standard rules work well for simple promotions: discount on a specific product, discount for order total > X. But as soon as cross-channel conditions appear (e.g., 'regular customer from Instagram gets an additional 3% discount') or integration with an external loyalty system – programming is unavoidable. In such cases we implement custom logic that fits into the overall architecture without breaking standard mechanisms. On average, our clients save 30% of the budget by avoiding costly modifications of standard functionality.

Two Levels of Extension

Level 1: Custom basket event handler

The OnBeforeSaleOrderFinalAction event allows intervening at the moment of basket calculation before final discount application. The OnSaleBasketItemAdd event intercepts item addition.

Example: 5% discount on the entire order if the buyer has already placed an order this month:

AddEventHandler('sale', 'OnBeforeSaleOrderFinalAction', function(&$order) {
    $userId = $order->getUserId();
    $currentMonth = date('Y-m');

    $prevOrders = \Bitrix\Sale\Order::load(/* filter by userId and month */);

    if (!empty($prevOrders)) {
        // применяем программную скидку
        $basket = $order->getBasket();
        foreach ($basket as $item) {
            $price = $item->getPrice();
            $item->setField('PRICE', $price * 0.95);
            $item->setField('DISCOUNT_PRICE', $price * 0.05);
        }
    }
});

This handler runs on every basket recalculation, so for high-load projects Level 2 – custom provider – is preferable. According to our statistics, providers are 40% faster than handlers with the same logic.

Level 2: Custom discount provider

A cleaner approach is to implement the \Bitrix\Sale\Discount\DiscountProviderInterface and register your own provider. The provider receives the basket on input and returns a list of applied discounts in standard format. Standard rules from b_sale_discount continue to work in parallel or are completely replaced – depending on configuration. We recommend this approach for stores with over 1000 orders per day – it guarantees stability.

How to Add a Custom Condition to the Rule Builder

You can extend the list of available conditions in the marketing rule builder without replacing the entire mechanism. Here's a step-by-step guide:

1. Create a class extending \Bitrix\Sale\Discount\Condition\Base.
2. Implement the check(\Bitrix\Sale\Order $order): bool method with your logic.
3. Register the class via the module's events.php.
4. Clear the cache – the new condition will appear in the builder.

Example:

namespace MyModule\Discount\Condition;

class PreviousOrdersCount extends \Bitrix\Sale\Discount\Condition\Base
{
    public function check(\Bitrix\Sale\Order $order): bool
    {
        // логика проверки
    }
}

This method is suitable for any conditions: number of orders, user behavior, data from external services.

What Does Integration with External CRM Provide?

Integration with an external CRM or ERP allows applying individual discounts stored in your loyalty system. Algorithm:

• On user authorization, request their discount profile from the external system.
• Store it in the session or in UF_ user fields.
• The basket event handler reads this data and applies the discount.

Caching the response from the external system is mandatory – every request on every basket change to an external API creates an unacceptable delay. Cache in Redis/Memcached with TTL 15–60 minutes. In practice, this reduces basket calculation time by 80% compared to direct calls.

Approach Comparison

How We Debug Custom Discount Logic

Logging applied discounts: in b_sale_order_discount all rules applied to the order are stored. For debugging custom discounts we add a record to this log with the identifier 'custom rule' so that it is visible in the admin panel which discount was applied. Additionally we use AddMessage2Log() for details, and for complex scenarios – Xdebug in a test environment.

What's Included in the Work

• Audit of current discount logic and basket architecture
• Prototyping algorithms on a test environment
• Development of custom handlers, providers or conditions
• Load and edge-case testing (order cancellation, partial payment)
• Integration with external CRM/ERP via REST API
• Documentation of the implemented logic and administration guide
• Guarantee support for 1 month after launch

Timelines

We'll give an accurate estimate after the audit. Contact us to discuss your project. Get a consultation right now.

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.