Symfony Design Patterns

Dependency Injection pattern

Imagine you have a class manager to manages sending mails (be called MailManager).

In this, you have to log mails that are sent. A good solution is to transform the MailManager class into a service and then inject class for creating logs (Monolog for example) into the MailManager creating a service.

To do this :

1- Declare future MailManager class as service (in services.yml)

services:
    mail.manager.class:
        class:     Vendor/YourBundle/Manager/MailManager

2- Inject logger existant service using argument method

services:
    mail.manager.class:
        class:    Project/Bundle/Manager/MailManager
        arguments: ["@logger"]    # inject logger service into constructor

3- Create MailManager class

<?php

namespace Project\Bundle\Manager;

use Symfony\Component\HttpKernel\Log\LoggerInterface;

class MailManager
{
  protected $logger;

  //initialized logger object
  public function __construct(LoggerInterface $logger)
  {
     $this->logger = $logger;
  }

   public function sendMail($parameters)
   {
      //some codes to send mail
      
      //example using logger
      $this->logger->info('Mail sending');
   }
}

4- Call MailManager in a Controller for example

<?php

class TestController extends Controller
{
    public function indexAction()
    {
        //some codes...

        //call mail manager service
        $mailManager = $this->get('mail.manager.class');
        //call 'sendMail' function from this service
        $mailManager->sendMail($parameters);
        
    }
}