Added _id in path_by_field method

.circleci/config.yml

@@ -54,11 +54,25 @@ jobs:
             composer update -n --prefer-dist
             php vendor/bin/phpunit
 
+  php81:
+    docker:
+      - image: cimg/php:8.1
+
+    working_directory: ~/project
+    steps:
+      - checkout
+      - run:
+          name: Run tests
+          command: |
+            composer update -n --prefer-dist
+            php vendor/bin/phpunit
+
 workflows:
   version: 2
   test:
     jobs:
       - php72
       - php73
       - php74
-      - php80
+      - php80
+      - php81

Model/Item.php

@@ -671,6 +671,10 @@ public static function createFromArray(array $array): self
      */
     public static function getPathByField(string $field)
     {
+        if ('_id' === $field) {
+            return $field;
+        }
+
         return in_array($field, ['id', 'type'])
             ? 'uuid.'.$field
             : 'indexed_metadata.'.$field;

Tests/Model/ItemTest.php

@@ -525,4 +525,16 @@ public function testMap()
         $this->assertEquals(10, $item->getScore());
         $this->assertNull($item->getCoordinate());
     }
+
+    /**
+     * @return void
+     */
+    public function testPathByField()
+    {
+        $this->assertEquals('_id', Item::getPathByField('_id'));
+        $this->assertEquals('uuid.id', Item::getPathByField('id'));
+        $this->assertEquals('uuid.type', Item::getPathByField('type'));
+        $this->assertEquals('indexed_metadata.another_id', Item::getPathByField('another_id'));
+        $this->assertEquals('indexed_metadata._field', Item::getPathByField('_field'));
+    }
 }