How to create a custom module in Drupal 8 & 9

Drupal 9 is the latest version of Drupal. There are significant differences between Drupal 8&9 and Drupal 7. Firstly, Drupal 8&9 requires the latest version of php5 to run. Drupal 8&9 uses a PHP framework called Symphony, which relies heavily on OOP. Another major change in Drupal 8&9 is the folder structure. In Drupal 8&9, all core modules are placed within core/ and all other modules are placed in root modules folder. Moreover, there are changes in the way modules are created. Read on to know how to create a custom module in Drupal 8&9.

A Drupal 8&9 custom module consists of three basic files:

1. mymodule.info.yml holds the module info

       name: My Module
       description: 'My Description Custom Module'
       core_version_requirement: ^8 || ^9 || ^10
       version: 1.0
       type: module
       package: Custom

2. mymodule.routing.yml file for holding ‘routing’ info or hook_menu

   mymodule.my_page:
     path: '/my-page'
     defaults:
       _controller: '\Drupal\mymodule\Controller\myModuleController::myPage'
       _title: 'Welcome to My Page'
     requirements: 
       _permission: 'access content'

3. myModuleController.php for controller classes and its callbacks.

   <?php
    namespace Drupal\mymodule\Controller;
    class myModuleController {
     public function myPage() {
       return array(
         '#markup' => 'Welcome to My Custom Page.'
       );
     }
    }
   ?>