Custom 1C-Bitrix Warehouse Management Module Development

When an online store on 1C-Bitrix works with multiple warehouses, the standard catalog module quickly falls short?

Typical pain points: an item exists in the database but is already reserved by another order – up to 15% of orders are lost due to overselling; managers manually track transfers; integration with 1C overwrites reservations. We have encountered this dozens of times: for example, a store with three warehouses in different cities lost up to 15% of orders due to the lack of a reservation mechanism. The solution is a custom warehouse management module that processes orders 3 times faster than standard accounting. Over the past years, we have implemented over 50 such modules integrated with 1C:UT, YooKassa, ATOL, and CDEK. Contact us for a consultation – we will tell you how to reduce losses.

Why standard functionality is insufficient?

The standard catalog module stores the total quantity of goods in a warehouse but does not distinguish between physical and available stock. There is no mechanism for reservation against a specific order, and no ability to set a warehouse priority for shipment. Inter-warehouse transfers are not recorded with history. According to 1C-Bitrix documentation (https://dev.1c-bitrix.ru/), the OnSaleOrderSaved event allows intercepting an order save – this is the key entry point for our reservation logic. Our solution with a separate reservation table surpasses standard accounting by 3 times in order processing speed.

How we extend the data schema?

The module adds two main tables: b_catalog_store_reservation and b_catalog_store_movement.

How does reservation work at order placement?

When an order is created, goods are reserved at the warehouse via the OnSaleOrderSaved event handler. The process consists of several steps:

1. When the order is saved, the OnSaleOrderSaved event fires.
2. For each item, the source warehouse is determined according to the selected strategy.
3. A record is created in the b_catalog_store_reservation table with the quantity and order ID.
4. When the order is paid or canceled, the reservation is automatically released (RELEASED_AT is filled).

\Bitrix\Main\EventManager::getInstance()->addEventHandler(
    'sale',
    'OnSaleOrderSaved',
    [ReservationService::class, 'onOrderSaved']
);

This schema ensures that two different orders cannot get the same product.

How to choose a warehouse for shipment?

The warehouse selection strategy is configured in the module settings:

• FIFO – older stock is shipped first (by receipt date).
• Nearest warehouse – based on customer geolocation (requires coordinates).
• Warehouse priority – uses the SORT field (lower = higher priority).
• Minimum stock – empties warehouses with the smallest stock.

If one warehouse does not have enough stock, the system automatically splits the shipment across multiple warehouses. This prevents order cancellations due to shortages at a single warehouse.

Calculation of available stock

Available stock = physical stock minus active reservations:

public static function getAvailable(int $storeId, int $productId): float
{
    $physical = \Bitrix\Catalog\StoreProductTable::getList([
        'filter' => ['=STORE_ID' => $storeId, '=PRODUCT_ID' => $productId],
        'select' => ['AMOUNT'],
    ])->fetch()['AMOUNT'] ?? 0;

    $reserved = \Bitrix\Main\Application::getConnection()->query(
        "SELECT COALESCE(SUM(QUANTITY), 0) as RES
         FROM b_catalog_store_reservation
         WHERE STORE_ID = {$storeId}
           AND PRODUCT_ID = {$productId}
           AND RELEASED_AT IS NULL"
    )->fetch()['RES'] ?? 0;

    return max(0, (float)$physical - (float)$reserved);
}

On the product card and in the cart, the available stock is displayed. This eliminates the situation where a customer buys a product that is no longer in reserve.

Administrative interface

Three sections are added to the admin panel:

• Stocks by warehouse – matrix of product × warehouse with physical and available stock, filtering by category and warehouse.
• Transfers – creating a transfer document, confirming receipt at the destination warehouse.
• Reservations – list of active reservations with the ability to manually release.

Integration with 1C

During integration via standard exchange (/bitrix/admin/1c_exchange.php), stock from the module is synchronized with b_catalog_store_product via the OnSuccessCatalogImport1C event handler. Reservations are not overwritten: stock from 1C is treated as physical, and available stock is recalculated automatically.

Development timelines

What is included in the work

• Module development with API and configuration documentation.
• Source code with comments, unit tests.
• Integration setup with 1C, payment gateways, and shipping companies.
• Administrator training.
• Post-project support: 6-month warranty from the delivery date.

Our expertise

Over 10 years of development experience, more than 50 projects for stores with various logistics. Certified specialists in the 1C-Bitrix platform. We guarantee adherence to deadlines and transparency of work. Savings from overselling can reach 15% of turnover. Contact us for a consultation – we will discuss your project without obligation.

Additional information about inventory management methods is available on Wikipedia: FIFO, inventory management.

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.