How to create a dynamic route in Drupal 8 and Drupal 9

Drupal 8/9 allows you to specify routes in a dynamic manner. To create dynamic routes, we initiate with the route_callbacks method in the routing.yml file.

Dynamic routes:

A method is used to implement dynamic routes. This method is added to module_name.routing.yml as a 'route_callbacks' entry.

route_callbacks:
 - '\Drupal\module_name\Routing\MyModuleRoutes::routes'

Create src/Routing/MyModuleRoutes.php file:

The dynamic routing method either returns an array of \Symfony\Component\Routing\Route objects or a \Symfony\Component\Routing\RouteCollection object.

<?php
/**
* @file
* Contains \Drupal\module_name\Routing\MyModuleRoutes.
*/
 
namespace Drupal\module_name\Routing;
 
use Symfony\Component\Routing\Route;
 
/**
* Defines dynamic routes.
*/
class MyModuleRoutes {
 
 /**
  * {@inheritdoc}
  */
 public function routes() {
   $routes = [];
   // Declares a single route under the name 'module_name.content'.
   // Returns an array of Route objects.
   $routes['module_name.content'] = new Route(
     // Path to attach this route to:
     '/hello_world',
     // Route defaults:
     [
       '_controller' => '\Drupal\module_name\Controller\ExampleController::content',
       '_title' => 'Hello'
     ],
     // Route requirements:
     [
       '_permission'  => 'access content',
     ]
   );
   return $routes;
 }
 
}

Create src/Controller/ExampleController.php file:

As you can see, this simply adds another layer between routing.yml and the Controller. Our Controller appears to be as follows:

<?php
namespace Drupal\module_name\Controller;
 
use Drupal\Core\Controller\ControllerBase;
 
 
class ExampleController extends ControllerBase {
 
 /**
  * @return string[]
  */
 public function content() {
   return [
     '#markup' => 'Hello world ?',
   ];
 }
 
}

Finally, we goto URL and navigate to /hello_world page then the output looks as follows:

Conclusion:

In Drupal 8/9 create dynamic routes by initiating with the route_callbacks method in the routing.yml file.