Drupal: Dynamic routes

#drupal #php #development

We know that starting with Drupal 8 we have a good Routing system. But I am faced with one limitation, I cannot define the route with the parameter in the first position ("/{param_1}/some/path"). And in this article I want to share a solution for this case.

Let's imagine that we have a list of articles, each of which belongs to a certain category (taxonomy term). I want to have a router for such a path "/{category}/{article_alias}/{view_mode}".

The list of categories can be changed at any time, so we cannot determine all possible routes in advance. The view_mode is just an additional parameter for demonstration.

Fortunately, Drupal allows us to declare our custom Routers. Let's create a new module for this.

modules/custom/dynamic_router/dynamic_router.info.yml:

name: Dynamic Router
type: module
description: 'Provides Dynamic routes for article CT.'
dependencies:
  - drupal:node
package: Custom
core_version_requirement: ^11

modules/custom/dynamic_router/dynamic_router.routing.yml:

route_callbacks:
  - '\Drupal\dynamic_router\Routing\DynamicRouter::routes'

We usually provide several custom routes in this file, but we can also define route_callback.

modules/custom/dynamic_router/src/Routing/DynamicRouter.php:

<?php

namespace Drupal\dynamic_router\Routing;

use Drupal\Core\DependencyInjection\ContainerInjectionInterface;
use Drupal\Core\Entity\EntityTypeManagerInterface;
use Symfony\Component\DependencyInjection\ContainerInterface;
use Symfony\Component\Routing\Route;

/**
 * Class provides dynamic routing for the articles.
 */
class DynamicRouter implements ContainerInjectionInterface {

  /**
   * Constructs DynamicRouter class.
   *
   * @param \Drupal\Core\Entity\EntityTypeManagerInterface $entity_type_manager
   *   The entity type manager service.
   */
  public function __construct(
    protected EntityTypeManagerInterface $entityTypeManager
  ) {}

  /**
   * {@inheritDoc}
   */
  public static function create(ContainerInterface $container) {
    return new static(
      $container->get('entity_type.manager')
    );
  }

  /**
   * Returns an array of route objects.
   *
   * @return \Symfony\Component\Routing\Route[]
   *   An array of route objects.
   */
  public function routes(): array {
    $routes = [];

    $terms = $this->entityTypeManager->getStorage('taxonomy_term')
      ->loadTree("article_categories", 0, NULL, TRUE);

    /** @var \Drupal\taxonomy\TermInterface $category */
    foreach ($terms as $category) {
      $category_path = $category->path->alias;
      $routes['category.' . $category->id() . '.article'] = new Route(
        $category_path . '/{node}/{view_mode}',
        ['_controller' => 'Drupal\dynamic_router\Controller\ArticleController::node'],
        ['_permission' => 'access content'],
      );
    }

    return $routes;
  }

}

For this example, I created a new taxonomy vocabulary with the machine name "article_categories"

And a simple controller, just to demonstrate, I returned the standard output of node builder using view_mode parameter from route.

modules/custom/dynamic_router/src/Controller/ArticleController.php:

<?php

namespace Drupal\dynamic_router\Controller;

use Drupal\Core\Controller\ControllerBase;
use Drupal\path_alias\AliasManagerInterface;
use Symfony\Component\DependencyInjection\ContainerInterface;
use Drupal\node\NodeInterface;

class ArticleController extends ControllerBase {

  /**
   * The entity type manager service.
   *
   * @var \Drupal\Core\Entity\EntityTypeManagerInterface
   */
  protected $entityTypeManager;

  /**
   * Constructs a ArticleController object.
   *
   * @param \Drupal\Core\Path\AliasManagerInterface $aliasManager
   *    The alias manager service.
   */
  public function __construct(
    protected AliasManagerInterface $aliasManager
  ) {}

  /**
   * {@inheritdoc}
   */
  public static function create(ContainerInterface $container) {
    return new static(
      $container->get('path_alias.manager'),
    );
  }

  /**
   * Renders a node as a render array.
   *
   * @param string $node
   *   The node alias.
   * @param string $view_mode
   *   View mode ('full', 'part').
   *
   * @return array
   *   A render array for the node.
   */
  public function node(string $node, string $view_mode): array {
    $path = $this->aliasManager->getPathByAlias('/' . $node);

    if (preg_match('/^\\/node\\/(\\d+)$/', $path, $matches)) {
      $nid = $matches[1];
      $node = $this->entityTypeManager()->getStorage('node')->load($nid);
    }

    if ($node instanceof NodeInterface && $node->isPublished()) {
      $view_builder = $this->entityTypeManager->getViewBuilder('node');
      return $view_builder->view($node, $view_mode);
    }
    else {
      return [
        '#markup' => $this->t('Node not found or unpublished.'),
      ];
    }
  }

}