thelebster · June 6, 2023 21:28 · Jun 6, 2023
diff --git a/drupal-widlcard-routes.md b/drupal-widlcard-routes.md
@@ -0,0 +1,95 @@
+The goal is to provide a dynamic (wildcard) route that should match on all nested routes that starts from some string.
+
+The main issue is that [Drupal routing system](https://www.drupal.org/docs/drupal-apis/routing-system/routing-system-overview), does not provide a clean way to describe a wildcard routes that should match some kind of pattern, like `/UserGuide`, `/UserGuide/Development_Notes` or `/UserGuide/Release_Notes/3.0.x` etc.
+
+Initial idea is to use dynamic routes, that will work in case when routes are known or could be generated by some pattern, like `/UserGuide/node/1`, `/UserGuide/node/2` etc. Otherwise this is not possible, like when the route could consist from the multiple undefined parts.
+
+As one possible solution, I decided to try the [inbound path processor](https://api.drupal.org/api/drupal/core%21lib%21Drupal%21Core%21PathProcessor%21InboundPathProcessorInterface.php/interface/InboundPathProcessorInterface/10) to catch destination path to redirect to the page controller, and pass an original path as a query parameter.
+
+File **example/example.routing.yml**:
+
+```
+example.user_guide:
+  path: '/UserGuide'
+  defaults:
+    _controller: '\Drupal\example\Controller\ExamplePageController::view'
+    _title: 'User Guide'
+  requirements:
+    _access: 'TRUE'
+```
+
+File **example/example.services.yml**:
+
+```
+services:
+  example.path_processor:
+    class: Drupal\example\PathProcessor\ExamplePathProcessor
+    tags:
+      - { name: path_processor_inbound, priority: 1000 }
+```
+
+File **example/src/PathProcessor/ExamplePathProcessor.php**:
+
+```
+<?php
+
+namespace Drupal\example\ExamplePathProcessor;
+
+use Drupal\Core\PathProcessor\InboundPathProcessorInterface;
+use Symfony\Component\HttpFoundation\Request;
+
+// Before PHP 8, use a polyfill.
+// @see https://www.php.net/manual/en/function.str-starts-with.php
+if (!function_exists('str_starts_with')) {
+  function str_starts_with($haystack, $needle) {
+    return (string) $needle !== '' && strncmp($haystack, $needle, strlen($needle)) === 0;
+  }
+}
+
+class ExamplePathProcessor implements InboundPathProcessorInterface {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function processInbound($path, Request $request) {
+    if (!str_starts_with($path, '/UserGuide')) return $path;
+    // Remove leading slash.
+    $original_path = ltrim(str_replace('/UserGuide', '', $path), '/');
+    $request->query->set('original_path', $original_path);
+    return '/UserGuide';
+  }
+}
+```
+
+File **example/src/Controller/ExamplePageController.php**:
+
+```
+<?php
+
+namespace Drupal\example\Controller;
+
+use Drupal\Core\Controller\ControllerBase;
+
+class ExamplePageController extends ControllerBase {
+
+  public function view() {
+    $request_query = \Drupal::request()->query->all();
+    
+    // Get an original path.
+    $original_path = $request_query['original_path'];
+    
+    // Do anything else...
+    // For example, try to fetch page content from some external API etc.
+    $page_content = self::getPageContent($original_path);
+    
+    if (empty($page_content)) {
+      // Return 404 not found if page does not exist.
+      throw new \Symfony\Component\HttpKernel\Exception\NotFoundHttpException();
+    }
+    
+    // Return a renderable array with a page content.
+    return $build;
+  }
+  
+}
+```