magento-module-development

Magento 2 Module Development

Overview

Build custom Magento 2 modules using the module architecture, dependency injection (DI), service contracts (interfaces), plugins (interceptors), observers, and the repository pattern. This skill covers the Magento 2 module skeleton, XML-based configuration, the Object Manager and DI container, custom REST/GraphQL API endpoints, and database schema management with db_schema.xml (declarative schema).

When to Use This Skill

• When building a custom module that adds new functionality to a Magento 2 store
• When extending or overriding core Magento behavior using plugins or preferences
• When creating custom REST API or GraphQL endpoints for headless integrations
• When adding custom database tables with declarative schema
• When implementing admin grids, forms, and system configuration

Core Instructions

1. Create the module skeleton

   Every Magento 2 module lives in app/code/Vendor/Module and requires at minimum two files:

   app/code/Acme/CustomModule/
   ├── etc/
   │   └── module.xml
   ├── registration.php
   ├── Api/
   │   └── CustomRepositoryInterface.php
   ├── Model/
   │   ├── CustomRepository.php
   │   └── ResourceModel/
   ├── Controller/
   ├── Block/
   ├── view/
   │   ├── frontend/
   │   └── adminhtml/
   └── Setup/
       └── Patch/
           └── Data/
   

   // registration.php
   <?php
   declare(strict_types=1);
   
   use Magento\Framework\Component\ComponentRegistrar;
   
   ComponentRegistrar::register(
       ComponentRegistrar::MODULE,
       'Acme_CustomModule',
       __DIR__
   );
   

   <!-- etc/module.xml -->
   <?xml version="1.0"?>
   <config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
           xsi:noNamespaceSchemaLocation="urn:magento:framework:Module/etc/module.xsd">
       <module name="Acme_CustomModule" setup_version="1.0.0">
           <sequence>
               <module name="Magento_Catalog"/>
               <module name="Magento_Sales"/>
           </sequence>
       </module>
   </config>