OpenAPI UI Hook to Event Subscriber

docroot/modules/custom/va_gov_api/js/json-schemas-table-filter.js

@@ -9,13 +9,14 @@
 
       rows.forEach(function(row) {
         // Get the first cell (td) of the row, which contains the schema label.
-        const firstCell = row.cells[0];
+        const schemaLabel = row.cells[0];
 
         // Remove all but 'VA.gov JSON:API'.
-        if (firstCell.textContent.trim() !== 'VA.gov JSON:API') {
+        if (schemaLabel.textContent.trim() !== 'VA.gov JSON:API') {
           row.remove();
         }
       });
     }
   }
 })(jQuery, Drupal, drupalSettings);
+

docroot/modules/custom/va_gov_api/src/EventSubscriber/AddJsEventSubscriber.php

@@ -0,0 +1,46 @@
+<?php
+
+namespace Drupal\va_gov_api\EventSubscriber;
+
+use Drupal\core_event_dispatcher\Event\Theme\PageAttachmentsEvent;
+use Drupal\core_event_dispatcher\PageHookEvents;
+use Symfony\Component\EventDispatcher\EventSubscriberInterface;
+use Symfony\Component\HttpFoundation\RequestStack;
+
+/**
+ * Add JS to the OpenAPI UI selector page so only one schema is displayed.
+ */
+class AddJsEventSubscriber implements EventSubscriberInterface {
+
+  /**
+   * The request.
+   */
+  protected RequestStack $requestStack;
+
+  /**
+   * Constructor.
+   */
+  public function __construct(RequestStack $requestStack) {
+    $this->requestStack = $requestStack;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function getSubscribedEvents(): array {
+    return [
+      PageHookEvents::PAGE_ATTACHMENTS => ['onPageAttachments'],
+    ];
+  }
+
+  /**
+   * Modify response to add JS script to a route.
+   */
+  public function onPageAttachments(PageAttachmentsEvent $event): void {
+    if ($this->requestStack->getCurrentRequest()->get('_route') === 'openapi.downloads') {
+      $attachments = &$event->getAttachments();
+      $attachments['#attached']['library'][] = 'va_gov_api/json_schemas_table_filter';
+    }
+  }
+
+}

docroot/modules/custom/va_gov_api/va_gov_api.services.yml

@@ -1,3 +1,9 @@
 # Increases the # of items in the response for any given jsonapi request.
 parameters:
   next_jsonapi.size_max: 2000
+services:
+  va_gov_api.add_js_to_ui:
+      class: Drupal\va_gov_api\EventSubscriber\AddJsEventSubscriber
+      arguments: ['@request_stack']
+      tags:
+      - { name: event_subscriber }