2

In a node preprocess hook I am getting breadcrumbs for the currently viewed node by doing the following:

$vars['breadcrumb'] = Drupal::service('breadcrumb')
    ->build(Drupal::routeMatch())->toRenderable();

This works fine as it uses Drupal::routeMatch() to get the matched route for the current request.

But I also want to get the breadcrumb for each node in a listing of several nodes. In this case I cannot use Drupal::routeMatch() since I want to get the breadcrumb for each node in the listing, not the current page. The problem is I cannot find a way of getting a RouteMatchInterface object (needed by the BreadcrumbBuilder) from a node object. I can get the url containing route information via $node->urlInfo()but there seems to be no way of getting from there to a route match either.

How can this be done?

Edit:

I found a way to get the route match for a certain node. Not sure if it's the ideal way but it gets the job done:

$routeName = $node->urlInfo()->getRouteName();
$routeParameters = $node->urlInfo()->getRouteParameters();
$route = Drupal::service('router.route_provider')->getRouteByName($routeName);
$routeMatch = new RouteMatch($routeName, $route, $routeParameters);

However passing the $routeMatch into PathBasedBredcrumbBuilder::create does not generate bredcrumbs for that route!

On closer inspection it seems that the built-in PathBasedBreadCrumbBuilder class completely ignores the passed in $routeMatch parameter and instead builds the breadcrumbs using the path of the current page, fetched using the injected RequestContext object. I think I would need to swap out this service with my own implementation which uses the passed in parameters somehow. To be continued...

1

I eventually solved it by creating my own subclass of the PathBasedBredcrumbBuilder from core. This class unlike core's version actually uses the passed in route_match and returns breadcrumbs based on that which makes it possible to get breadcrumbs for a certain node (or any other given route).

I still need to calculate the route match from the current node to pass to the build method (as shown in the question). It feels a bit awkward since the route_match is converted back into a url object in the build method but it works and it is the cleanest solution i've come up with so far.

Below is the subclass:

namespace Drupal\contextual_breadcrumbs;

use Drupal\system\PathBasedBreadcrumbBuilder;
use Drupal\Core\Routing\RequestContext;
use Drupal\Core\Routing\RouteMatchInterface;
use Drupal\Core\Url;

class ContextualPathBasedBreadcrumbBuilder extends PathBasedBreadcrumbBuilder {

    /**
    * {@inheritdoc}
    */
    public function build(RouteMatchInterface $route_match) {

      /// Set request context from passed in $route_match
      $url = Url::fromRouteMatch($route_match);
      if ($request = $this->getRequestForPath($url->toString(), [])) {
        $context = new RequestContext();
        $context->fromRequest($request);
        $this->context = $context;
      } 

      // Build breadcrumbs using new context ($route_match is unused)
      return parent::build($route_match);
    }

}
0

It seems you could use the service_collector to just add your custom ContextualPathBasedBreadcrumbBuilder.

For that just add in your modules services.yml:

  my_custom_module.breadcrumb:
    class: Drupal\ my_custom_module.breadcrumb\CustomBreadcrumbBuilder
    arguments: ['@router.request_context', '@access_manager', '@router', '@path_processor_manager', '@config.factory',  '@title_resolver', '@current_user', '@path.current', '@path.matcher']
    tags:
      - { name: breadcrumb_builder, priority: 1002 }

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