Issue #3269633 by mkalkbrenner: ActiveFiltersParsed event should know the configured filter key

src/Event/ActiveFiltersParsed.php

@@ -34,6 +34,13 @@ final class ActiveFiltersParsed extends Event {
    */
   private $queryParameters;
 
+  /**
+   * The facet parameter filter key.
+   *
+   * @var string
+   */
+  private $filterKey;
+
   /**
    * QueryStringCreated constructor.
    *
@@ -44,10 +51,11 @@ final class ActiveFiltersParsed extends Event {
    * @param \Symfony\Component\HttpFoundation\ParameterBag $queryParameters
    *   The get parameters to use.
    */
-  public function __construct($facetsource_id, array $activeFilters, ParameterBag $queryParameters) {
+  public function __construct($facetsource_id, array $activeFilters, ParameterBag $queryParameters, $filter_key) {
     $this->facetsourceId = $facetsource_id;
     $this->queryParameters = $queryParameters;
     $this->activeFilters = $activeFilters;
+    $this->filterKey = $filter_key;
   }
 
   /**
@@ -93,4 +101,14 @@ final class ActiveFiltersParsed extends Event {
     return $this->queryParameters;
   }
 
+  /**
+   * Get the facet parameter filter key.
+   *
+   * @return string
+   *   The facet parameter filter key.
+   */
+  public function getFilterKey() {
+    return $this->filterKey;
+  }
+
 }

src/Plugin/facets/url_processor/QueryString.php

@@ -354,7 +354,7 @@ class QueryString extends UrlProcessorPluginBase {
     }
 
     // Allow other modules to alter the parsed active filters.
-    $event = new ActiveFiltersParsed($facet_source_id, $active_filters, $this->request->query);
+    $event = new ActiveFiltersParsed($facet_source_id, $active_filters, $url_parameters, $this->filterKey);
     $this->eventDispatcher->dispatch($event);
     $this->activeFilters = $event->getActiveFilters();
   }

src/Plugin/facets/widget/LinksWidget.php

@@ -65,10 +65,6 @@ class LinksWidget extends WidgetPluginBase {
       $url_processor = $urlProcessorManager->createInstance($facet->getFacetSourceConfig()->getUrlProcessorName(), ['facet' => $facet]);
       $active_filters = $url_processor->getActiveFilters();
 
-      if (isset($active_filters[''])) {
-        unset($active_filters['']);
-      }
-
       unset($active_filters[$facet->id()]);
 
       // Only if there are still active filters, use url generator.

src/UrlProcessor/UrlProcessorInterface.php

@@ -3,6 +3,7 @@
 namespace Drupal\facets\UrlProcessor;
 
 use Drupal\facets\FacetInterface;
+use Symfony\Component\HttpFoundation\Request;
 
 /**
  * Interface UrlProcessorInterface.
@@ -79,4 +80,12 @@ interface UrlProcessorInterface {
    */
   public function setActiveFilters(array $active_filters);
 
+  /**
+   * Returns the request.
+   *
+   * @return \Symfony\Component\HttpFoundation\Request
+   *   The request.
+   */
+  public function getRequest(): Request;
+
 }

src/UrlProcessor/UrlProcessorPluginBase.php

@@ -152,4 +152,11 @@ abstract class UrlProcessorPluginBase extends ProcessorPluginBase implements Url
     }
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public function getRequest(): Request {
+    return $this->request;
+  }
+
 }