Order on document id

src/InMemoryDocumentStore.php

@@ -20,6 +20,7 @@
 use EventEngine\DocumentStore\OrderBy\AndOrder;
 use EventEngine\DocumentStore\OrderBy\Asc;
 use EventEngine\DocumentStore\OrderBy\Desc;
+use EventEngine\DocumentStore\OrderBy\DocId;
 use EventEngine\DocumentStore\OrderBy\OrderBy;
 use EventEngine\Persistence\InMemoryConnection;
 use function array_key_exists;
@@ -644,15 +645,20 @@ private function sort(&$docs, OrderBy $orderBy)
         };
 
         $getField = function (array $doc, OrderBy $orderBy) {
+            if ($orderBy instanceof DocId) {
+                return $doc['docId'];
+            }
+
             if ($orderBy instanceof Asc || $orderBy instanceof Desc) {
                 $field = $orderBy->prop();
 
                 return (new ArrayReader($doc['doc']))->mixedValue($field);
             }
 
             throw new \RuntimeException(\sprintf(
-                'Unable to get field from doc: %s. Given OrderBy is neither an instance of %s nor %s',
-                \json_encode($doc['doc']),
+                'Unable to get field from doc: %s. Given OrderBy is neither an instance of %s, %s nor %s',
+                \json_encode($doc),
+                DocId::class,
                 Asc::class,
                 Desc::class
             ));

src/OrderBy/DocId.php

@@ -0,0 +1,36 @@
+<?php
+/**
+ * This file is part of event-engine/php-document-sore.
+ * (c) 2018-2021 prooph software GmbH <contact@prooph.de>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+declare(strict_types=1);
+
+namespace EventEngine\DocumentStore\OrderBy;
+
+final class DocId implements OrderBy
+{
+    private $direction;
+
+    public function __construct($direction = 'ASC') {
+        $this->direction = $direction;
+    }
+
+    public static function fromArray(array $data): OrderBy
+    {
+        return new self($data['direction'] ?? OrderBy::ASC);
+    }
+
+    public function toArray(): array
+    {
+        return ['direction' => $this->direction];
+    }
+
+    public function direction()
+    {
+        return $this->direction;
+    }
+}