[Adr] Kernel events vs controllers

.gitattributes

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+/adr                    export-ignore

adr/0000-kernel-events.md

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+# Kernel events
+
+* Status: new
+* Deciders: @lchrusciel, @loic425, @Zales0123
+* External advices: @soyuka, @dunglas, @mtarld
+
+## Context and Problem Statement
+
+ResourceController has all the actions, a lot of pretty similar code on each action and hard to maintain/test.
+and it is not flexible enough in its behavior.
+
+## Considered Options
+
+* Use Kernel events
+* Use one controller per action
+
+## PreWriteListener
+
+### With kernel events
+
+```php
+$resourceEvent = $this->eventDispatcher->dispatchPreEvent($operation->getName(), $configuration, $controllerResult);
+$request->attributes->set('resource_event', $resourceEvent);
+
+if (!$resourceEvent->isStopped()) {
+    return;
+}
+
+if (null !== $resourceEventResponse = $resourceEvent->getResponse()) {
+    $event->setControllerResult($resourceEventResponse);
+
+    return;
+}
+
+if ($operation instanceof CreateOperationInterface) {
+    $event->setControllerResult($this->redirectHandler->redirectToIndex($configuration, $controllerResult));
+
+    return;
+}
+
+$event->setControllerResult($this->redirectHandler->redirectToResource($configuration, $controllerResult));
+```
+
+Moreover, it allows to use a custom controller free of dependencies injection.
+
+```php
+#[Resource(alias: 'app.book')]
+#[Create(
+    factory: false, // to disable resource factory 
+    controller: CreateBookAction::class, 
+    template: 'book/create.html.twig',
+)]
+class Book implements ResourceInterface
+```
+
+```php
+class CreateBookAction
+{
+    public function __invoke(#[CurrentUser] $user): Book
+    {
+        return (new Book())->setCreatedBy($user);
+    }
+}
+```
+
+For end-user, he could also disable the existing listeners and build its own way to implement it.
+
+### With controllers
+
+With controllers, to have a quick look for all these little differences, we have to create a new service with this code and it creates another service injected in our controller.