82 lines
2.4 KiB
Markdown
82 lines
2.4 KiB
Markdown
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---
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title: Experimenting with events in Drupal 8
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date: 2018-08-21
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excerpt: Trying a different way of structuring Drupal modules, using event subscribers and autowiring.
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tags:
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- drupal
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- drupal-8
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- drupal-planet
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- php
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- symfony
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promoted: true
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---
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I’ve been experimenting with moving some code to Drupal 8, and I’m quite
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intrigued by a different way that I’ve tried to structure it - using event
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subscribers, building on some of the takeaways from Drupal Dev Days.
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Here is how this module is currently structured:
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{.border .p-1}
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Note that there is no `opdavies_blog.module` file, and rather than calling
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actions from within a hook like `opdavies_blog_entity_update()`, each action
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becomes it’s own event subscriber class.
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This means that there are no long `hook_entity_update` functions, and instead
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there are descriptive, readable event subscriber class names, simpler action
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code that is responsibile only for performing one task, and you’re able to
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inject and autowire dependencies into the event subscriber classes as services -
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making it easier and cleaner to use dependency injection, and simpler write
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tests to mock dependencies when needed.
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The additional events are provided by the
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[Hook Event Dispatcher module](https://www.drupal.org/project/hook_event_dispatcher).
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## Code
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`opdavies_blog.services.yml`:
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```yaml
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services:
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Drupal\opdavies_blog\EventSubscriber\PostToMedium:
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autowire: true
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tags:
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- { name: event_subscriber }
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Drupal\opdavies_blog\EventSubscriber\SendTweet:
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autowire: true
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tags:
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- { name: event_subscriber }
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```
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<div class="note" markdown="1">
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Adding `autowire: true` is not required for the event subscriber to work. I’m using it to automatically inject any dependencies into the class rather than specifying them separately as arguments.
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</div>
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`src/EventSubscriber/SendTweet.php`:
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```php
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namespace Drupal\opdavies_blog\EventSubscriber;
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use Drupal\hook_event_dispatcher\Event\Entity\EntityUpdateEvent;
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use Drupal\hook_event_dispatcher\HookEventDispatcherInterface;
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use Symfony\Component\EventDispatcher\EventSubscriberInterface;
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class SendTweet implements EventSubscriberInterface {
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...
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public static function getSubscribedEvents() {
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return [
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HookEventDispatcherInterface::ENTITY_UPDATE => 'sendTweet',
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];
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}
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public function sendTweet(EntityUpdateEvent $event) {
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// Perform checks and send the tweet.
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}
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}
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```
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