Add singleton

README.md

@@ -9,6 +9,7 @@ A set of Doctrine Entity features to automate repetitive entity tasks and ease d
 - [x] [UUID](docs/uuid.md)
 - [x] [IP Tagged](docs/ip_tagged.md)
 - [x] [Soft Delete](docs/soft_delete.md)
+- [x] [Singleton](docs/singleton.md)
 - [ ] Logging
 - [ ] Tree
 - [ ] Translation

config/services.php

@@ -6,6 +6,7 @@
 use Rami\EntityKitBundle\EventListener\Authored\AuthoredListener;
 use Rami\EntityKitBundle\EventListener\IpTagged\IpTaggedListener;
 use Rami\EntityKitBundle\EventListener\LoggedEntity\LoggedEntityListener;
+use Rami\EntityKitBundle\EventListener\Singleton\SingletonListener;
 use Rami\EntityKitBundle\EventListener\Slugged\SluggedListener;
 use Rami\EntityKitBundle\EventListener\SoftDelete\SoftDeleteFilterListener;
 use Rami\EntityKitBundle\EventListener\TimeStamped\TimeStampedListener;
@@ -60,4 +61,9 @@
         ->set(SoftDeleteFilterListener::class)
         ->args([new Reference(ManagerRegistry::class), new Reference(ParameterBagInterface::class)])
         ->tag('kernel.event_listener', ['event' => 'kernel.controller', 'method' => 'onKernelController']);
+
+    $services
+        ->set(SingletonListener::class)
+        ->args([new Reference(ManagerRegistry::class)])
+        ->tag('doctrine.event_listener', ['event' => 'prePersist']);
 };

docs/singleton.md

@@ -0,0 +1,19 @@
+Singleton
+-
+Add a singleton entity where only one entity can be created or new entities cannot be created if one or more already exists.
+
+This is good for an app configuration saved in the database
+
+use the `Singleton` attribute on your entity class
+
+```php
+use Rami\EntityKitBundle\Common\Attributes\Singleton
+
+#[Singleton]
+class Blog 
+{
+  // properties omitted
+}
+```
+
+This prevents new entities of type `Blog` from being created.

src/Common/Attributes/Singleton.php

@@ -0,0 +1,20 @@
+<?php
+/*
+ * Copyright (c) 2025.
+ *
+ * This file is part of the Entity Kit Bundle project
+ * @author Abdellah Ramadan <ramadanabdel24@gmail.com>
+ *
+ * For the full copyright and license information,
+ * please view the LICENSE file that was distributed with this source code.
+ */
+
+namespace Rami\EntityKitBundle\Common\Attributes;
+
+use Attribute;
+
+#[\Attribute(Attribute::TARGET_CLASS)]
+class Singleton
+{
+
+}

src/Entity/Traits/TreeTrait.php

@@ -0,0 +1,8 @@
+<?php
+
+namespace Rami\EntityKitBundle\Entity\Traits;
+
+trait TreeTrait
+{
+
+}

src/EventListener/Singleton/SingletonListener.php

@@ -0,0 +1,47 @@
+<?php
+/*
+ * Copyright (c) 2025.
+ *
+ * This file is part of the Entity Kit Bundle project
+ * @author Abdellah Ramadan <ramadanabdel24@gmail.com>
+ *
+ * For the full copyright and license information,
+ * please view the LICENSE file that was distributed with this source code.
+ */
+
+namespace Rami\EntityKitBundle\EventListener\Singleton;
+
+use Doctrine\ORM\Event\PrePersistEventArgs;
+use Doctrine\Persistence\ManagerRegistry;
+use JetBrains\PhpStorm\NoReturn;
+use Rami\EntityKitBundle\Common\Attributes\Singleton;
+use Rami\EntityKitBundle\Exceptions\EntityCountException;
+
+class SingletonListener
+{
+
+    public function __construct(private ManagerRegistry $managerRegistry)
+    {
+    }
+
+    /**
+     * @throws EntityCountException
+     */
+    #[NoReturn] public function prePersist(PrePersistEventArgs $args): void
+    {
+        $entity = $args->getObject();
+
+        $reflection = new \ReflectionObject($entity);
+        $attributes = $reflection->getAttributes(Singleton::class);
+
+        if (count($attributes) === 0) {
+            return;
+        }
+
+        $existingEntity = $this->managerRegistry->getManager()->getRepository(get_class($entity))->findOneBy([]);
+
+        if (null !== $existingEntity) {
+            throw new EntityCountException();
+        }
+    }
+}

src/Exceptions/EntityCountException.php

@@ -0,0 +1,22 @@
+<?php
+/*
+ * Copyright (c) 2025.
+ *
+ * This file is part of the Entity Kit Bundle project
+ * @author Abdellah Ramadan <ramadanabdel24@gmail.com>
+ *
+ * For the full copyright and license information,
+ * please view the LICENSE file that was distributed with this source code.
+ */
+
+namespace Rami\EntityKitBundle\Exceptions;
+
+use Symfony\Component\HttpFoundation\Response;
+
+class EntityCountException extends \Exception
+{
+    protected $code = Response::HTTP_CONFLICT;
+
+    protected $message = 'This entity is a singleton. Entity has already been created.';
+
+}