Issue #3094192 by mglaman: Support filtering on index fields

src/Resource/IndexResource.php

@@ -12,6 +12,7 @@ use Drupal\jsonapi\Query\OffsetPage;
 use Drupal\jsonapi\ResourceResponse;
 use Drupal\jsonapi_resources\Resource\EntityResourceBase;
 use Drupal\search_api\IndexInterface;
+use Drupal\search_api\Item\Field;
 use Drupal\search_api\Item\ItemInterface;
 use Drupal\search_api\ParseMode\ParseModeInterface;
 use Drupal\search_api\ParseMode\ParseModePluginManager;
@@ -82,7 +83,7 @@ final class IndexResource extends EntityResourceBase implements ContainerInjecti
     $query->range($pagination->getOffset(), $pagination->getSize());
 
     if ($request->query->has('filter')) {
-      $this->applyFiltersToQuery($request, $query);
+      $this->applyFiltersToQuery($request, $query, $cacheability);
     }
 
     // Get the results and convert to JSON:API resource object data.
@@ -106,10 +107,12 @@ final class IndexResource extends EntityResourceBase implements ContainerInjecti
    *   The request.
    * @param \Drupal\search_api\Query\QueryInterface $query
    *   The query.
+   * @param \Drupal\Core\Cache\CacheableMetadata $cacheability
+   *   The cache metadata.
    *
    * @throws \Drupal\Component\Plugin\Exception\PluginException
    */
-  protected function applyFiltersToQuery(Request $request, QueryInterface $query): void {
+  protected function applyFiltersToQuery(Request $request, QueryInterface $query, CacheableMetadata $cacheability): void {
     $parse_mode = $this->parseModeManager->createInstance('terms');
     assert($parse_mode instanceof ParseModeInterface);
     $query->setParseMode($parse_mode);
@@ -119,6 +122,17 @@ final class IndexResource extends EntityResourceBase implements ContainerInjecti
       $query->keys($filter['fulltext']);
       unset($filter['fulltext']);
     }
+
+    $index = $query->getIndex();
+    $filterable_fields = array_filter($index->getFields(), static function (Field $field) {
+      return $field->getType() !== 'text';
+    });
+    foreach ($filter as $filterable_field_name => $filterable_field_value) {
+      if (!isset($filterable_fields[$filterable_field_name])) {
+        throw new CacheableBadRequestHttpException($cacheability, sprintf('The %s field is not filterable.', $filterable_field_name));
+      }
+      $query->addCondition($filterable_field_name, $filterable_field_value);
+    }
   }
 
   /**

tests/src/Functional/IndexResourceTest.php

@@ -78,6 +78,7 @@ final class IndexResourceTest extends BrowserTestBase {
    * @dataProvider noQueryDataProvider
    * @dataProvider paginationDataProvider
    * @dataProvider fulltextDataProvider
+   * @dataProvider filterDataProvider
    */
   public function testCollection(array $query, int $expected_count, array $expected_ids, array $expected_links_keys): void {
     $request_options = [];
@@ -173,4 +174,43 @@ final class IndexResourceTest extends BrowserTestBase {
     ];
   }
 
+  /**
+   * Filter data provider.
+   *
+   * @return \Generator
+   *   The data.
+   */
+  public function filterDataProvider(): \Generator {
+    yield [
+      [
+        'filter' => [
+          'keywords' => 'strawberry',
+        ],
+      ],
+      2,
+      [4, 5],
+      [],
+    ];
+    yield [
+      [
+        'filter' => [
+          'keywords' => 'banana',
+        ],
+      ],
+      1,
+      [5],
+      [],
+    ];
+    yield [
+      [
+        'filter' => [
+          'keywords' => 'orange',
+        ],
+      ],
+      3,
+      [1, 2, 5],
+      [],
+    ];
+  }
+
 }