Drupal 8 page template suggestion by path alias

Drupal 8 page template suggestion by path alias, here is a snippet that I wrote for adding a couple of extra page template suggestions for my theme.

Drupal 8 page template suggestion by path alias

Basically What I wanted to do is to have two extra rules for page template suggestions:

1. Template suggestion by content type page--contettype.html.twig
2. For “page” content type have page templates by
   • page url: /about => page--alias--about.html.twig
   • page url: /about/us => page--alias--about-us.html.twig

This helped me come up with nice looking templates for custom post types and be able to add special things in special pages.

Here is the hook I wrote YOURTHEME_theme_suggestions_page_alter in my theme’s YOURTHEME.theme file. (Replace YOURTHEME with your theme’s name)

/**
 * Implements hook_theme_suggestions_HOOK_alter().
 * Page template for content type page--contettype.html.twig
 * For "page" content type we refine it further by adding page--alias--"the-alias"
 * example: page content type wit alias "about/us"  => "page--alias--about-us" template file
 */
 function YOURTHEME_theme_suggestions_page_alter(array &$suggestions, array $variables) {

   // Response codes for Access Denied and Page Not Found. 
   $system_codes = [403, 404];
   if (Drupal::request()->attributes->get('exception') && 
        $status_code = Drupal::request()->attributes->get('exception')->getStatusCode()) {
     // Add Basic Page suggestion if one of above response codes.
     if (in_array($status_code, $system_codes)) {
       $suggestions[] = 'page';
     }
   }

    if ($node = Drupal::routeMatch()->getParameter('node')) {
      $content_type = $node->bundle();
      $suggestions[] = 'page__'.$content_type;

        // for "page" content type only
        // if ($content_type == 'page'){

          if (in_array($content_type, array('webform','page'))) {

          $current_path = Drupal::service('path.current')->getPath();
          $alias = Drupal::service('path.alias_manager')->getAliasByPath($current_path);

          if ($alias != '')  {

            // break up the alias "/about/us"  => "", "about", "" ,"us"
            $parts = explode('/', $alias);

            // we only start suggestion with one "-" because first "/" will become extra "-"
            $suggestion = 'page__alias';

            foreach ($parts as $part) {
                // subsequent suggestions get appended
                $suggestion .= "_" . "$part";
            }

            // turn "-" in "_"
            $suggestion = str_replace("-", "_", $suggestion);
            $suggestions[] = $suggestion;

          }
        }

    }

  }

Cheers!