Notify post author about new comments by sending email

app/AppKernel.php

@@ -22,8 +22,7 @@ public function registerBundles()
             new CodeExplorerBundle\CodeExplorerBundle(),
             new AppBundle\AppBundle(),
             new Doctrine\Bundle\FixturesBundle\DoctrineFixturesBundle(), // used for initial population of non-SQLite databases in production envs
-            // uncomment the following line if your application sends emails
-            // new Symfony\Bundle\SwiftmailerBundle\SwiftmailerBundle(),
+            new Symfony\Bundle\SwiftmailerBundle\SwiftmailerBundle(),
         ];
 
         // Some bundles are only used while developing the application or during

app/Resources/translations/messages.en.xlf

@@ -277,6 +277,15 @@
                 <target>Post deleted successfully!</target>
             </trans-unit>
 
+            <trans-unit id="notification.comment_created">
+                <source>notification.comment_created</source>
+                <target>Your post received a comment!</target>
+            </trans-unit>
+            <trans-unit id="notification.comment_created.description">
+                <source>notification.comment_created.description</source>
+                <target><![CDATA[Your post "%title%" has received a new comment. You can read the comment by following <a href="%link%">this link</a>]]></target>
+            </trans-unit>
+
             <trans-unit id="help.app_description">
                 <source>help.app_description</source>
                 <target><![CDATA[This is a <strong>demo application</strong> built in the Symfony Framework to illustrate the recommended way of developing Symfony applications.]]></target>

app/Resources/views/blog/post_show.html.twig

@@ -30,6 +30,7 @@
 
     {% for comment in post.comments %}
         <div class="row post-comment">
+            <a name="comment_{{ comment.id }}"></a>
             <h4 class="col-sm-3">
                 <strong>{{ comment.authorEmail }}</strong> {{ 'post.commented_on'|trans }}
                 {# it's not mandatory to set the timezone in localizeddate(). This is done to

app/config/config.yml

@@ -83,9 +83,9 @@ doctrine:
 # stores options that change the application behavior and parameters.yml
 # stores options that change from one server to another
 #
-# swiftmailer:
-#     transport: "%mailer_transport%"
-#     host:      "%mailer_host%"
-#     username:  "%mailer_user%"
-#     password:  "%mailer_password%"
-#     spool:     { type: memory }
+swiftmailer:
+    transport: "%mailer_transport%"
+    host:      "%mailer_host%"
+    username:  "%mailer_user%"
+    password:  "%mailer_password%"
+    spool:     { type: memory }

app/config/config_dev.yml

@@ -29,5 +29,5 @@ monolog:
         #    type:   chromephp
         #    level:  info
 
-#swiftmailer:
-#    delivery_address: me@example.com
+swiftmailer:
+    disable_delivery:  true

app/config/parameters.yml.dist

@@ -31,12 +31,9 @@ parameters:
     # $ php bin/console doctrine:schema:create
     # $ php bin/console doctrine:fixtures:load
 
-    # Uncomment these parameters if your application sends emails:
-    #
-    # mailer_transport:  smtp
-    # mailer_host:       127.0.0.1
-    # mailer_user:       ~
-    # mailer_password:   ~
-    #
     # If you don't use a real mail server, you can send emails via your Gmail account.
     # see http://symfony.com/doc/current/cookbook/email/gmail.html
+    mailer_transport:  smtp
+    mailer_host:       127.0.0.1
+    mailer_user:       ~
+    mailer_password:   ~

app/config/services.yml

@@ -31,9 +31,17 @@ services:
         tags:
             - { name: kernel.event_listener, event: kernel.request, method: onKernelRequest }
 
-    # Event subscribers are similar to event listeners but they don't need to add
-    # a separate tag for each listened event. Instead, the PHP class of the event
-    # subscriber includes a method that returns the list of listened events.
+    app.comment_notification:
+        class: AppBundle\EventListener\CommentNotificationListener
+        arguments: ['@mailer', '@router', '@translator', '%app.notifications.email_sender%']
+        # The "method" attribute of this tag is optional and defaults to "on + camelCasedEventName"
+        # If the event is "comment.created" the method executed by default is "onCommentCreated()".
+        tags:
+            - { name: kernel.event_listener, event: comment.created, method: onCommentCreated }
+
+    # Event subscribers are similar to event listeners but they don't need service tags.
+    # Instead, the PHP class of the event subscriber includes a method that returns
+    # the list of events listened by that class.
     # See http://symfony.com/doc/current/event_dispatcher.html#creating-an-event-subscriber
     app.console_subscriber:
         class: AppBundle\EventListener\ConsoleEventSubscriber

src/AppBundle/Controller/BlogController.php

@@ -13,13 +13,15 @@
 
 use AppBundle\Entity\Comment;
 use AppBundle\Entity\Post;
+use AppBundle\Events;
 use AppBundle\Form\CommentType;
 use Sensio\Bundle\FrameworkExtraBundle\Configuration\Cache;
 use Sensio\Bundle\FrameworkExtraBundle\Configuration\Method;
 use Sensio\Bundle\FrameworkExtraBundle\Configuration\ParamConverter;
 use Sensio\Bundle\FrameworkExtraBundle\Configuration\Route;
 use Sensio\Bundle\FrameworkExtraBundle\Configuration\Security;
 use Symfony\Bundle\FrameworkBundle\Controller\Controller;
+use Symfony\Component\EventDispatcher\GenericEvent;
 use Symfony\Component\HttpFoundation\Request;
 use Symfony\Component\HttpFoundation\Response;
 
@@ -96,6 +98,20 @@ public function commentNewAction(Request $request, Post $post)
             $entityManager->persist($comment);
             $entityManager->flush();
 
+            // When triggering an event, you can optionally pass some information.
+            // For simple applications, use the GenericEvent object provided by Symfony
+            // to pass some PHP variables. For more complex applications, define your
+            // own event object classes.
+            // See http://symfony.com/doc/current/components/event_dispatcher/generic_event.html
+            $event = new GenericEvent($comment);
+
+            // When an event is dispatched, Symfony notifies it to all the listeners
+            // and subscribers registered to it. Listeners can modify the information
+            // passed in the event and they can even modify the execution flow, so
+            // there's no guarantee that the rest of this controller will be executed.
+            // See http://symfony.com/doc/current/components/event_dispatcher.html
+            $this->get('event_dispatcher')->dispatch(Events::COMMENT_CREATED, $event);
+
             return $this->redirectToRoute('blog_post', ['slug' => $post->getSlug()]);
         }
 

src/AppBundle/EventListener/CommentNotificationListener.php

@@ -0,0 +1,96 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace AppBundle\EventListener;
+
+use Symfony\Component\EventDispatcher\GenericEvent;
+use Symfony\Component\Routing\Generator\UrlGeneratorInterface;
+use Symfony\Component\Translation\TranslatorInterface;
+
+/**
+ * Notifies post's author about new comments.
+ *
+ * @author Oleg Voronkovich <oleg-voronkovich@yandex.ru>
+ */
+class CommentNotificationListener
+{
+    /**
+     * @var \Swift_Mailer
+     */
+    private $mailer;
+
+    /**
+     * @var TranslatorInterface
+     */
+    private $translator;
+
+    /**
+     * @var UrlGeneratorInterface
+     */
+    private $urlGenerator;
+
+    /**
+     * @var string
+     */
+    private $sender;
+
+    /**
+     * Constructor.
+     *
+     * @param \Swift_Mailer         $mailer
+     * @param UrlGeneratorInterface $urlGenerator
+     * @param TranslatorInterface   $translator
+     * @param string                $sender
+     */
+    public function __construct(\Swift_Mailer $mailer, UrlGeneratorInterface $urlGenerator, TranslatorInterface $translator, $sender)
+    {
+        $this->mailer = $mailer;
+        $this->urlGenerator = $urlGenerator;
+        $this->translator = $translator;
+        $this->sender = $sender;
+    }
+
+    /**
+     * @param GenericEvent $event
+     */
+    public function onCommentCreated(GenericEvent $event)
+    {
+        $comment = $event->getSubject();
+        $post = $comment->getPost();
+
+        $linkToPost = $this->urlGenerator->generate('blog_post', [
+            'slug' => $post->getSlug(),
+            '_fragment' => 'comment_'.$comment->getId(),
+        ], UrlGeneratorInterface::ABSOLUTE_URL);
+
+        $subject = $this->translator->trans('notification.comment_created');
+        $body = $this->translator->trans('notification.comment_created.description', [
+            '%title%' => $post->getTitle(),
+            '%link%' => $linkToPost,
+        ]);
+
+        // Symfony uses a library called SwiftMailer to send emails. That's why
+        // email messages are created instantiating a Swift_Message class.
+        // See http://symfony.com/doc/current/email.html#sending-emails
+        $message = \Swift_Message::newInstance()
+            ->setSubject($subject)
+            ->setTo($post->getAuthorEmail())
+            ->setFrom($this->sender)
+            ->setBody($body, 'text/html')
+        ;
+
+        // In app/config/config_dev.yml the 'disable_delivery' option is set to 'true'.
+        // That's why in the development environment you won't actually receive any email.
+        // However, you can inspect the contents of those unsent emails using the debug toolbar.
+        // See http://symfony.com/doc/current/email/dev_environment.html#viewing-from-the-web-debug-toolbar
+        $this->mailer->send($message);
+    }
+}

src/AppBundle/Events.php

@@ -0,0 +1,32 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace AppBundle;
+
+/**
+ * This class defines the names of all the events dispatched in
+ * the Symfony Demo application. It's not mandatory to create a
+ * class like this, but it's considered a good practice.
+ *
+ * @author Oleg Voronkovich <oleg-voronkovich@yandex.ru>
+ */
+final class Events
+{
+    /**
+     * For the event naming conventions, see:
+     * http://symfony.com/doc/current/components/event_dispatcher.html#naming-conventions.
+     *
+     * @Event("Symfony\Component\EventDispatcher\GenericEvent")
+     *
+     * @var string
+     */
+    const COMMENT_CREATED = 'comment.created';
+}