The document provides an overview of routing in Drupal 8. It discusses how routing works in Drupal 8 using Symfony routing files instead of hook_menu. Key points include: routes define paths and controllers; routes are defined in .routing.yml files; routes provide access control and pass arguments to controllers; dynamic routes can be defined programmatically; and parameter upcasting converts route parameters to objects.

1. A Deep Dive into Drupal
8 Routing
DrupalCamp Mumbai
April 1, 2017
Naveen Valecha

2. About me
● Drupal: naveenvalecha
● Git Administer on Drupal.org
● Site Maintainer of groups.drupal.org
● Twitter: @_naveenvalecha_
● Web: https://www.valechatech.net
● Drupal 5,6,7,8

3. Agenda
● What are Routes. Why we need them?
● Routes and Controllers
● Access checking on routes
● Custom Access Checkers
● CSRF Prevention on routes
● Altering routes
● Dynamic Routes
● Parameter Upcasting

4. Routing System
● hook_menu to Symfony2 routing
● Replace paths with route names for rendering
links
● Converting all page callbacks to controllers
● New breadcrumb system, new menu link system,
conversion of local tasks and actions to plugins

5. Routing System - Cont.
● menu links, local tasks, local actions, contextual
links
● Split all the pieces from hook_menu into YAML
files finally
● module.routing.yml module.links.menu.yml
● module.links.task.yml module.links.action.yml
● module.contextual.yml

6. hook_menu to Symfony Routing
● PHP array to multiple yaml files
● Performance improvements
● Developer Experience(DX)
● Clean Code
● Procedural to Object Oriented(OO)

7. D7 hook_menu
$items['admin/appearance/settings'] = array(
'title' => 'Settings',
'description' => 'Configure default and theme specific settings.',
'page callback' => 'drupal_get_form',
'page arguments' => array('system_theme_settings'),
'access arguments' => array('administer themes'),
'type' => MENU_LOCAL_TASK,
'file' => 'system.admin.inc',
'weight' => 20,
);

8. D8 system.routing.yml
system.theme_settings:
path: '/admin/appearance/settings'
defaults:
_form: 'DrupalsystemFormThemeSettingsForm'
_title: 'Appearance settings'
requirements:
_permission: 'administer themes'

9. D8 system.links.task.yml
system.theme_settings:
route_name: system.theme_settings
title: 'Settings'
base_route: system.themes_page
weight: 100

10. Route
● A route is a path which is defined for Drupal to
return some sort of content on. For example, the
default front page, '/node' is a route.
● Use mm.routing.yml for defining routes

11. Routes and Controllers
● The routing system is responsible for matching
paths to controllers, and you define those
relations in routes. You can pass on additional
information to your controllers in the route.
Access checking is integrated as well.

12. Route - Slug
entity.node.preview:
path: '/node/preview/{node_preview}/{view_mode_id}'
defaults:
_controller: 'DrupalnodeControllerNodePreviewController::view'
_title_callback: 'DrupalnodeControllerNodePreviewController::title'
requirements:
_node_preview_access: '{node_preview}'
options:
parameters:
node_preview:
type: 'node_preview'

13. /**
* Defines a controller to render a single node in preview.
*/
class NodePreviewController extends EntityViewController {
/**
* {@inheritdoc}
*/
public function view(EntityInterface $node_preview, $view_mode_id =
'full', $langcode = NULL) {
$node_preview->preview_view_mode = $view_mode_id;
$build = parent::view($node_preview, $view_mode_id);
return $build;
}
}

14. example.content:
path: '/example'
defaults:
_controller:
'DrupalexampleControllerExampleController::content'
custom_arg: 12
requirements:
_permission: 'access content'
// ...
public function content(Request $request, $custom_arg) {
// Now can use $custom_arg (which will get 12 here) and $request.
}

15. Routes Structure
● Path(*): /node/preview/{node_preview}/{view_mode_id}
● defaults(*)
○ _controller:
DrupalnodeControllerNodePreviewController::view
○ _form: DrupalCoreFormFormInterface
○ _entity_view, _entity_form:
○ _title(optional), _title_context(optional),
_title_callback(optional)

16. Routes Structure
● methods(optional)
● Requirements
○ _permission, _role, _access, _entity_access,
_custom_access, _format,
_content_type_format
○ _module_dependencies
○ _csrf_token

17. Access checking
Permission
requirements:
_permission: 'administer content types'
Role
requirements:
_role: 'administrator'

18. Access checking - Custom
class NodeRevisionAccessCheck implements AccessInterface {
public function access(Route $route, AccountInterface $account, $node_revision =
NULL, NodeInterface $node = NULL) {
if ($node_revision) {
$node = $this->nodeStorage->loadRevision($node_revision);
}
$operation = $route->getRequirement('_access_node_revision');
return AccessResult::allowedIf($node && $this->checkAccess($node, $account,
$operation))->cachePerPermissions()->addCacheableDependency($node);
}
}

19. Route - CSRF Protection
aggregator.feed_refresh:
path: '/admin/config/services/aggregator/update/{aggregator_feed}'
defaults:
_controller:
'DrupalaggregatorControllerAggregatorController::feedRefresh'
_title: 'Update items'
requirements:
_permission: 'administer news feeds'
_csrf_token: 'TRUE'

20. Routes - Altering
class NodeAdminRouteSubscriber extends RouteSubscriberBase {
protected function alterRoutes(RouteCollection $collection) {
if ($this->configFactory->get('node.settings')->get('use_admin_theme')) {
foreach ($collection->all() as $route) {
if ($route->hasOption('_node_operation_route')) {
$route->setOption('_admin_route', TRUE);
}
}
}
}
}

21. Dynamic Routes
Image.routing.yml
route_callbacks:
- 'DrupalimageRoutingImageStyleRoutes::routes'

22. Dynamic Routes - Cont.
class ImageStyleRoutes implements ContainerInjectionInterface {
public function routes() {
$routes = [];
$directory_path = $this->streamWrapperManager->getViaScheme('public')->getDirectoryPath();
$routes['image.style_public'] = new Route(
'/' . $directory_path . '/styles/{image_style}/{scheme}',
[ '_controller' => 'DrupalimageControllerImageStyleDownloadController::deliver', ],
[ '_access' => 'TRUE', ]
);
return $routes;
}
}

23. Route-Parameter Upcasting
entity.node.preview:
path: '/node/preview/{node_preview}/{view_mode_id}'
defaults:
_controller: 'DrupalnodeControllerNodePreviewController::view'
_title_callback: 'DrupalnodeControllerNodePreviewController::title'
requirements:
_node_preview_access: '{node_preview}'
options:
parameters:
node_preview:
type: 'node_preview'

24. Route-Parameter Upcasting Cont.
node.services.yml
node_preview:
class: DrupalnodeParamConverterNodePreviewConverter
arguments: ['@user.private_tempstore']
tags:
- { name: paramconverter }
lazy: true

25. Route-Parameter Upcasting Cont.
class NodePreviewConverter implements ParamConverterInterface {
public function convert($value, $definition, $name, array $defaults) {
$store = $this->tempStoreFactory->get('node_preview');
if ($form_state = $store->get($value)) {
return $form_state->getFormObject()->getEntity();
}
}
public function applies($definition, $name, Route $route) {
if (!empty($definition['type']) && $definition['type'] == 'node_preview') {
return TRUE;
}
return FALSE;
}

26. What’s for Drupal 9?
● Consider having a single class for Match Dumper,
Route Provider and Route Builder
● Automatically unserialize request data and
serialize outgoing data

27. References
● http://symfony.com/doc/current/components/
routing.html
● https://www.drupal.org/docs/8/api/routing-syste
m

28. Questions?

29. THANK YOU!