Add a new example

Author: javiereguiluz

components/uid.rst

@@ -155,6 +155,35 @@ type, which converts to/from UUID objects automatically::
 
     The UUID type was introduced in Symfony 5.2.
 
+There is no generator to assign UUIDs automatically as the value of your entity
+primary keys, but you can use instead the following::
+
+    namespace App\Entity;
+
+    use Doctrine\ORM\Mapping as ORM;
+    // ...
+
+    class User implements UserInterface
+    {
+        /**
+         * @ORM\Id
+         * @ORM\Column(type="ulid", unique=true)
+         */
+        private $id;
+
+        public function __construct()
+        {
+            $this->id = new Ulid();
+        }
+
+        public function getId(): Ulid
+        {
+            return $this->id;
+        }
+
+        // ...
+    }
+
 When using built-in Doctrine repository methods (e.g. ``findOneBy()``), Doctrine
 knows how to convert these UUID types to build the SQL query
 (e.g. ``->findOneBy(['user' => $user->getUuid()])``). However, when using DQL