How to Build a Custom Access Check Writer

The phrase “Custom Access Check Writer” generally refers to one of two completely different concepts depending on your industry:

Software Engineering (Drupal Web Development): Writing a custom service class (an “Access Checker”) to evaluate route access and determine whether a user is allowed to view or execute a specific page/action.

FinTech/Accounting (Physical Check Printing): Designing and developing a custom software module that formats bank information, routing numbers, and signature blocks to print legal physical checks onto blank stock paper.

Option 1: Building a Custom Access Check Writer (Drupal API)

If you are developing a web application using Drupal, an access checker is a backend service that evaluates custom routing rules dynamically (e.g., checking user history or external API fields before loading a page). Step 1: Create the Access Checker Class

Create a PHP file inside your custom module under src/Access/CheckWriterAccessCheck.php. It must implement AccessInterface and contain an access() method returning an AccessResult.

namespace Drupal\your_module\Access; use Drupal\Core\Routing\Access\AccessInterface; use Drupal\Core\Session\AccountInterface; use Drupal\Core\Access\AccessResult; class CheckWriterAccessCheck implements AccessInterface { public function access(AccountInterface \(account) { // Insert your custom business logic here if (\)account->hasPermission(‘access custom check system’)) { return AccessResult::allowed(); } return AccessResult::forbidden(); } } Use code with caution. Step 2: Register the Checker as a Service

Define your service in your_module.services.yml. You must tag it with name: access_check and supply an applies_to key string matching your custom tag.

services: your_module.access_check_writer: class: Drupal\your_module\Access\CheckWriterAccessCheck tags: - { name: access_check, applies_to: _custom_check_writer_access } Use code with caution. Step 3: Apply it to your Routing Rules

Bind the requirement directly to the specific page or feature routes in your your_module.routing.yml file. Custom Access Check | Drupal.org