Add documentation for AsEventListener attribute (#1583)

Co-authored-by: Gabriel Ostrolucký <gadelat@gmail.com>

Resources/doc/event-listeners.rst

@@ -0,0 +1,103 @@
+Event Listeners
+===============
+
+In opposite to :doc:`Entity Listeners </entity-listeners>`, Event listeners
+are services that listen for all entities in your application.
+
+See https://www.doctrine-project.org/projects/doctrine-orm/en/latest/reference/events.html#implementing-event-listeners
+for more info on event listeners.
+
+To register a service to act as an event listener you have to tag it with the
+``doctrine.event_listener`` tag:
+
+Starting with Doctrine bundle 2.8, you can use the ``AsDoctrineListener``
+attribute to tag the service.
+
+.. configuration-block::
+
+    .. code-block:: php-attributes
+
+        // src/App/EventListener/SearchIndexer.php
+        namespace App\EventListener;
+
+        use Doctrine\Bundle\DoctrineBundle\Attribute\AsDoctrineListener;
+        use Doctrine\ORM\Event\LifecycleEventArgs;
+
+        #[AsDoctrineListener('postPersist'/*, 500, 'default'*/)]
+        class SearchIndexer
+        {
+            public function postPersist(LifecycleEventArgs $event): void
+            {
+                // ...
+            }
+        }
+
+    .. code-block:: yaml
+
+        # config/services.yaml
+        services:
+            # ...
+
+            App\EventListener\SearchIndexer:
+                tags:
+                    -
+                        name: 'doctrine.event_listener'
+                        # this is the only required option for the lifecycle listener tag
+                        event: 'postPersist'
+
+                        # listeners can define their priority in case multiple subscribers or listeners are associated
+                        # to the same event (default priority = 0; higher numbers = listener is run earlier)
+                        priority: 500
+
+                        # you can also restrict listeners to a specific Doctrine connection
+                        connection: 'default'
+
+    .. code-block:: xml
+
+        <!-- config/services.xml -->
+        <?xml version="1.0" encoding="UTF-8" ?>
+        <container xmlns="http://symfony.com/schema/dic/services"
+            xmlns:doctrine="http://symfony.com/schema/dic/doctrine">
+            <services>
+                <!-- ... -->
+
+                <!--
+                    * 'event' is the only required option that defines the lifecycle listener
+                    * 'priority': used when multiple subscribers or listeners are associated to the same event
+                    *             (default priority = 0; higher numbers = listener is run earlier)
+                    * 'connection': restricts the listener to a specific Doctrine connection
+                -->
+                <service id="App\EventListener\SearchIndexer">
+                    <tag name="doctrine.event_listener"
+                        event="postPersist"
+                        priority="500"
+                        connection="default"/>
+                </service>
+            </services>
+        </container>
+
+    .. code-block:: php
+
+        // config/services.php
+        namespace Symfony\Component\DependencyInjection\Loader\Configurator;
+
+        use App\EventListener\SearchIndexer;
+
+        return static function (ContainerConfigurator $configurator) {
+            $services = $configurator->services();
+
+            // listeners are applied by default to all Doctrine connections
+            $services->set(SearchIndexer::class)
+                ->tag('doctrine.event_listener', [
+                    // this is the only required option for the lifecycle listener tag
+                    'event' => 'postPersist',
+
+                    // listeners can define their priority in case multiple subscribers or listeners are associated
+                    // to the same event (default priority = 0; higher numbers = listener is run earlier)
+                    'priority' => 500,
+
+                    // you can also restrict listeners to a specific Doctrine connection
+                    'connection' => 'default',
+                ])
+            ;
+        };

Resources/doc/index.rst

@@ -8,5 +8,6 @@ configuration options, console commands and even a web debug toolbar collector.
 
     installation
     entity-listeners
+    event-listeners
     custom-id-generators
     configuration