Conditional logic in Bitrix forms: implementation & validation

A feedback form with 15 fields displays all 15 at once. Five are only needed for legal entities, three for a specific request type. The user scrolls through the excess and leaves. Conversion drops by 30–50%. Conditional logic dynamically hides irrelevant fields: selected "Legal entity" — TIN and KPP appear. Filling time drops from 5 to 3 minutes — saving up to 40%. We implement such logic turnkey with server-side validation and documentation. We'll assess your project for free within one day. Contact us for a consultation — get an accurate estimate.

What problems we solve

Typical service order form: client selects type — "Individual" or "Legal entity". Without conditional logic, all fields are visible at once, and filling time increases by 40%. Another scenario: subscription form — the "Phone" field is required only when SMS notifications are chosen. Field redundancy leads to validation errors and lower conversion. Yet another example: webinar registration — the "City" field appears only when offline participation is selected. Such scenarios occur in 70% of projects.

We solve three key problems:

• Redundancy: irrelevant fields are hidden, the form is compact. Conversion increases by 30–50% in test projects.
• Validation errors: hidden fields are not required on the server. Submission errors drop to zero.
• Performance: lightweight native JavaScript — no jQuery, does not slow down the page. Form load time improves by 200 ms.

How we do it

Stack: form module (1C-Bitrix), bitrix:form.result.new component, native JavaScript (ES5+). Each field is rendered with an id following the pattern field_[SID] — an anchor for the logic. We use data-attributes to describe conditions.

Implementation via data-attributes

Example TIN field shown only when client type is "company":

<div class="form-row" id="row_CLIENT_TYPE">
    <!-- field rendering -->
</div>
<div class="form-row" id="row_INN" data-condition-field="CLIENT_TYPE" data-condition-value="company" style="display:none">
    <!-- field rendering -->
</div>

The JavaScript handler attaches a change event to controlling fields and checks conditions on each change. If the value matches, it shows the row; otherwise hides it. Hidden fields are cleared (value = '', checked = false).

This code is 3 times simpler and faster than including a third-party library like jQuery UI. It requires no extra requests and works immediately.

How to implement multiple conditions (AND/OR)?

For fields with multiple conditions, use the data-condition-rules attribute:

data-condition-rules='[{"field":"CLIENT_TYPE","value":"company"},{"field":"REQUEST_TYPE","value":"credit"}]'

Server-side validation of hidden fields

A hidden field should not be required on submission. The standard form module checks the REQUIRED flag without considering conditions. Workaround via the OnBeforeResultAdd event handler:

AddEventHandler('form', 'OnBeforeResultAdd', function($formId, &$arFields) {
    if (($arFields['form_field_CLIENT_TYPE'] ?? '') !== 'company') {
        unset($arFields['form_field_INN']);
    }
});

This approach ensures the form does not throw an error for a hidden field. Learn more about the event in the REST API documentation.

Approach comparison: native JS vs jQuery

Native JS is preferable for performance and self-containment. In 30 projects we abandoned jQuery — form load time reduced by 15%.

Why server-side validation is mandatory?

The client may disable JavaScript or intentionally submit hidden fields. Server-side check via OnBeforeResultAdd prevents writing invalid data. This is a mandatory step in production solutions. Without it, a required field may remain empty while the form is saved with blank data. "It is recommended to use the OnBeforeResultAdd handler for server-side validation" — 1C-Bitrix documentation

Work process

What is included in the work

• Copy and modify the form.result.new component template.
• Write JavaScript logic using data-attributes.
• Implement server-side validation via the OnBeforeResultAdd event.
• Test on all browsers (Chrome, Firefox, Safari, Edge).
• Access to the modified component template (Git repository).
• Documentation for conditions and API.
• Training for your developer (1 hour online session).
• Post-deployment support for 2 weeks.

Timelines and cost

Timelines — from 3 to 10 days depending on complexity (number of fields, condition types). Cost: from 30 000 ₽ for simple forms (up to 10 fields, single conditions). For complex cases (multiple AND/OR conditions, custom validation) — from 60 000 ₽. We'll assess your project for free within one day. Our certified specialists have worked with Bitrix for over 10 years and have implemented more than 50 form customization projects with a 100% success rate. Guaranteed results: if the logic doesn't work as specified, we fix it at no extra cost.

Contact us to discuss your task. Order development — get a consultation and an accurate timeline estimate.

What Professional 1C-Bitrix Installation Includes

We start by checking innodb_buffer_pool_size. The default MySQL value (128 MB) is a death sentence for an online store with a catalog of 10,000+ items. We set 70–80% of available RAM on a dedicated server, 50% on VPS. This single setting speeds up the site by 2–3 times compared to the default. We'll assess your project in one day — get a consultation. Contact us to order turnkey installation with performance guarantee.

How to Choose Hosting and Edition for 1C-Bitrix Installation?

BitrixVM is a virtual machine with a pre-installed stack: nginx + Apache, PHP-FPM, MySQL/MariaDB, Sphinx, Push server. For VPS — the best start. Everything is already configured for Bitrix, including OPcache, log rotation, and firewall. Management via web panel on port 8890. Bitrix documentation recommends starting with BitrixVM for predictable performance.

VPS/VDS is the sweet spot. Minimum configuration for a medium online store: 2 vCPU, 4 GB RAM, SSD. Optimal: 4 vCPU, 8 GB RAM. OS: Ubuntu 22.04 or Debian 12. If not BitrixVM, we configure the stack manually for the task. Virtual hosting — only for business cards and landing pages. Requirements: PHP 8.0+, MySQL 5.7+ / MariaDB 10.0+, 512 MB RAM, .htaccess. 1C-Bitrix hosting partners guarantee compatibility. Dedicated server — for highload. Typical architecture: web server separate, database separate, Redis/Memcached separate. For Enterprise edition — web cluster with load balancer. Cloud (Yandex Cloud, VK Cloud, Selectel) — when load spikes: sales, seasonal peaks. Autoscaling via Managed Kubernetes or simple VM vertical scaling.

Choosing the edition is equally important. A common mistake: choosing "Small Business" for a store that grows to B2B with wholesale prices and three warehouses in six months. Upgrading to "Business" — pay the difference, data is not lost, but it's better to plan ahead. Our specialists select the edition for current tasks and with room for growth. For example, the "Business" license (about 35,000 RUB) pays off through multi-warehouse and 1C exchange, while the wrong choice can lead to a loss of up to 30,000 RUB monthly on excess resources.

What Server Settings Are Critical for 1C-Bitrix?

Web Server and PHP

nginx as reverse proxy + Apache (mod_php) or nginx + PHP-FPM directly. The second option saves memory — Apache is not needed. But some Bitrix modules use .htaccess, so for compatibility we sometimes keep Apache. nginx configuration: fastcgi_read_timeout 300 — for long operations (1C import), client_max_body_size 1024m — large file uploads. Block access to .settings.php, .settings_extra.php, bitrix/.settings.php — they contain database passwords. Rewrite rules from urlrewrite.php — Bitrix generates them, but with nginx + PHP-FPM they need to be duplicated. PHP 8.0–8.2 with extensions: mbstring, curl, gd, xml, json, opcache, redis/memcached. Key php.ini settings: opcache.memory_consumption=256, opcache.max_accelerated_files=20000, max_execution_time=300, memory_limit=512M, upload_max_filesize=100M, post_max_size=128M.

Database and Caching

MySQL/MariaDB. Key my.cnf parameters: innodb_buffer_pool_size — 70–80% RAM, innodb_log_file_size=256M, tmp_table_size=256M, max_heap_table_size=256M, thread_pool_size — number of CPU cores. Encoding utf8mb4 mandatory, otherwise emoji and special characters break. Redis is preferable to Memcached for Bitrix — supports persistent connections and is more reliable. In production, Redis handles concurrent writes three times faster than Memcached under typical load. Configure in .settings_extra.php:

'cache' => ['value' => ['type' => ['class_name' => '\\Bitrix\\Main\\Data\\CacheEngineRedis']]]
'session' => ['value' => ['mode' => 'default', 'handlers' => ['general' => ['type' => 'redis']]]]

sudo apt install redis-server
sudo systemctl enable redis

SSL, Email, and Cron

SSL — Let's Encrypt via certbot in 90% of cases. Redirect HTTP → HTTPS (301), HSTS, TLS 1.2/1.3, OCSP Stapling. In Bitrix, switch to HTTPS in the main module settings. Email: abandon mail() — connect SMTP (Yandex.Mail for domain, Mail.ru for Business). Be sure to configure SPF, DKIM, DMARC. Without SPF, emails go to spam. Test deliverability via mail-tester.com — score 9+/10. Cron: Bitrix agents switch to system cron — * * * * * /usr/bin/php /var/www/bitrix/modules/main/tools/cron_events.php. Schedule 1C exchange (15–60 min), search reindex, backups (mysqldump + rsync, rotation 7+4), temporary file cleanup.

Security and Administration

File system: owner www-data, directories 755, files 644, upload 775. nginx blocks access to configuration files. Enable Bitrix Proactive Protection — WAF, activity control (block after 5 failed attempts), kernel integrity check. For admin panel: two-factor authentication via Google Authenticator or OTP, restrict access by IP via nginx for paranoid.

How Long Does 1C-Bitrix Installation and Configuration Take?

Post-Installation Checklist

1. Performance Monitor (/bitrix/admin/perfmon_panel.php) — aim for 30+ points. Below 20 means serious configuration issues.
2. System Check — automatic check of all parameters. Red items must be fixed, yellow — case by case.
3. Security Scanner — check for typical vulnerabilities.
4. PageSpeed Insights — TTFB < 200ms on VPS, LCP < 2.5s.
5. Test 1C exchange — if integration is planned, verify CommerceML exchange before launch.

Additionally, check software versions, caching settings, cron operation, SSL certificate, SPF/DKIM/DMARC, access rights, delete default users and pages. For projects with 54-FZ, ensure fiscalization is configured via OFD provider.

Deliverables

• Fully configured server for 1C-Bitrix with MySQL, PHP, nginx optimization.
• Installed and activated license of the required edition.
• SSL certificate, email settings, cron and backups.
• Documentation: all configuration parameters, access credentials, cron tasks.
• Content manager training: how to log into admin panel, add products, upload images.
• Post-installation support for 30 days — consultations on settings.

Why Trust Professionals with Installation?

Incorrect installation means lost time and money. We've seen projects where a store on "Start" couldn't handle 50 visitors because innodb_buffer_pool_size wasn't configured. After migrating to VPS with correct configuration, the site "flew". Incorrect configuration can cost 30,000 RUB monthly due to excessive resource consumption. You get a ready-made architecture that scales. Order turnkey 1C-Bitrix installation — get a reliable platform for business growth. Contact us for a free consultation: we'll calculate the cost and time for your project. Over 7 years of experience, 120+ Bitrix projects implemented, including highload stores with million-item catalogs. Get in touch — we'll help configure Bitrix for your project.