Creating a simple Hello module in Drupal 8

Drupal 8 is has many advanced CMS features with using the most advanced features of PHP language and integrates number of third party libraries.  Drupal 8 makes use of OOP concepts heavily while using PHP classes, objects, namespaces and many design patterns using these.  Symfony is a PHP framework that Drupal borrows from in order to reduce code duplication across various PHP projects. Much of the code that Drupal 8 uses to handle routing, sessions and the services container, amongst other things, is borrowed from Symfony. Drupal 8 makes use of PHP annotations — @docblock comments added to your code using a special syntax — for plugin discovery and to provide additional context/meta-data for code that’s being executed.

Let us create our first module in Drupal 8 using the following steps.

1. Create folder with module machine name in the sites/all/modules directory or modules/custom directory. I’m creating a hello_world module , I created it in the modules/custom directory.
2. Let Drupal 8 know about your module with an .info.yml file. I have created hello_world.info.yml file. Following are its contents.

   name: Hellow World Module
   description: Creates module to display Hellow WOrld on a page
   core: 8.x
   package: custom
   type: module
   version: 1.0
   php: 5.6

   We should add the name and description. Also need to define core and type. Also it needs to define the version and optionally minimum php version needed too.

3. Let Drupal 8 know the paths by .routing.yml file. It maps the path and and code that gets executed when that path is accessed.

   hello_world.hello:
       path: '/hello'
       defaults:
           _controller: Drupal\hello_world\Controller\HelloController::hello
           _title: 'This is title from router'
       requirements:
           _permission: 'access content'

    

4. Next we need to add the controller class which has the code that is executed when the path is accessed.

   <?php
   
   namespace Drupal\hello_world\Controller;
   
   use Drupal\Core\Controller\ControllerBase;
   
   class HelloController extends ControllerBase {
   
       public function content() {
           return [
               "#type" => 'markup',
               '#markup' => $this->t("This is a content added")
           ];
       }
   
       public function hello() {
           return [
               '#type' => 'markup',
               '#markup' => 'This is another content to hello'
           ];
       }
   
   }

    

5. After writing above code and if you visit your modules page in Drupal 8 , you’ll see your module listed. Enable the module and visit /hello you’ll see the output as defined by the controller.

This is the simple way that can be used to create a module in Drupal 8.