Applying Domain Driven Design with Symfony

When we learn Symfony2 from the documentation, it provides us with easy and convenient ways of getting the job done. Over time our projects grow and this early convenience can become an obstacle. In this session Marek will focus on how to make our code less dependent on Symfony2 and more domain focused.

Transcript

1. Applying Domain Driven Design with Symfony Marek Matulka 16 Apr 2014
2. Marek Matulka @super_marek Software engineer at SensioLabs UK Photo by @cakper
3. the easy way
4. (not applying DDD) the easy way*
5. Typical Symfony project...
6. Typical Symfony project... … starts with intention to write: * high quality code * reusable code * portable code * code you’re proud of
8. Typical Symfony controller... use Symfony\Bundle\FrameworkBundle\Controller\Controller; class RegistrationController extends Controller { public function registerAction($id) { $conference = $this->getDoctrine() ->getRepository(‘AcmeConferenceBundle:Conference’) ->find($id); if ($this->get(‘acme_conference.enrolment.service’) ->enrol($conference, $this->getUser())) { $this->get(‘acme_conference.notification.service’) ->notify($this->getUser(), ‘success’); } } }
9. Typical Symfony controller... Dependency Injection * used as a service locator Fat controllers * with actions full of business logic
10. NO TESTS?!
11. Typical Symfony controller... Over time it gets difficult to change. Then we are afraid to change it.
12. Typical Project Architecture... Acme\TestBundle\Entity ← Models Acme\TestBundle\Resource\views ← Views Acme\TestBundle\Controller ← Controllers
13. Typical Project Architecture... Acme\TestBundle\Entity ← Models Acme\TestBundle\Resource\views ← Views Acme\TestBundle\Controller ← Controllers FAT Controllers Thin Models
14. Typical Symfony project...
15. Typical Symfony project... ...ends full of: * tightly coupled objects * objects that are difficult to re-use * code you’re afraid to change * code you cannot test
16. Why it ended like that?
17. Why it ended like that? * poor understanding of the core domain * bad names * urge to use framework’s goodies * ContainerAware is evil * locked into framework’s structure * Acme\Bundle\TestBundle\Entity
18. Is there another way?
19. the right way
20. (in my humble opinion) the right way*
21. Forget about the framework
23. Forget about the framework
24. namespace Acme\ConferenceBundle\Controller; use Symfony\Bundle\FrameworkBundle\Controller\Controller; class RegistrationController extends Controller { public function registerAction($id) { $conference = $this->getDoctrine() ->getRepository(‘AcmeConferenceBundle:Conference’) ->find($id); if ($this->get(‘acme_conference.enrolment.service’) ->enrol($conference, $this->getUser())) { $this->get(‘acme_conference.notification.service’) ->notify($this->getUser(), ‘success’); $this->redirect(‘registration_successful’) } $this->redirect(‘registration_failed’); } }
25. Make your dependencies explicit
26. namespace Acme\ConferenceBundle\Controller; use Symfony\Bundle\FrameworkBundle\Controller\Controller; class RegistrationController extends Controller { public function registerAction($id) { $conference = $this->getDoctrine() ->getRepository(‘AcmeConferenceBundle:Conference’) ->find($id); if ($this->get(‘acme_conference.enrolment.service’) ->enrol($conference, $this->getUser())) { $this->get(‘acme_conference.notification.service’) ->notify($this->getUser(), ‘success’); return $this->redirect(‘registration_successful’); } return $this->redirect(‘registration_failed’); } }
27. namespace Acme\ConferenceBundle\Controller; use Symfony\Bundle\FrameworkBundle\Controller\Controller; class RegistrationController extends Controller { public function registerAction($id) { $conference = $this->getDoctrine() ->getRepository(‘AcmeConferenceBundle:Conference’) ->find($id); if ($this->get(‘acme_conference.enrolment.service’) ->enrol($conference, $this->getUser())) { $this->get(‘acme_conference.notification.service’) ->notify($this->getUser(), ‘success’); return $this->redirect(‘registration_successful’); } return $this->redirect(‘registration_failed’); } } Repository Response Service Service Value
28. namespace Acme\ConferenceBundle\Controller; use Symfony\Bundle\FrameworkBundle\Controller\Controller; class RegistrationController extends Controller { public function registerAction($id) { $conference = $this->getDoctrine() ->getRepository(‘AcmeConferenceBundle:Conference’) ->find($id); if ($this->get(‘acme_conference.enrolment.service’) ->enrol($conference, $this->getUser())) { $this->get(‘acme_conference.notification.service’) ->notify($this->getUser(), ‘success’); return $this->redirect(‘registration_successful’); } return $this->redirect(‘registration_failed’); } } ConferenceRepository RedirectResponse ConferenceEnrolment EnrolmentNotification Conference
29. Use interfaces to describe communication
30. namespace Acme\ConferenceBundle\Controller; use Sensio\Bundle\FrameworkExtraBundle\Configuration\Route; use Sensio\Bundle\FrameworkExtraBundle\Configuration\ParamConverter; use Acme\Learning\Conference; class RegistrationController { /** * @Route("/conference/{id}/enrol") * @ParamConverter("conference", class="AcmeConferenceBundle:Conference") */ public function registerAction(Conference $conference) { if ($this->get(‘acme_conference.enrolment.service’) ->enrol($conference, $this->getUser())) { $this->get(‘acme_conference.notification.service’) ->notify($this->getUser(), ‘success’); return $this->redirect(‘registration_successful’); } return $this->redirect(‘registration_failed’); } }
31. namespace Acme\ConferenceBundle\Controller; use Sensio\Bundle\FrameworkExtraBundle\Configuration\Route; use Sensio\Bundle\FrameworkExtraBundle\Configuration\ParamConverter; use Acme\Enrolment\ConferceEnrolment; class RegistrationController { public function __construct(ConferceEnrolment $enrolment) { $this->enrolment = $enrolment; } /** * @Route("/conference/{id}/enrol") * @ParamConverter("conference", class="AcmeConferenceBundle:Conference") */ public function registerAction(Conference $conference) { if ($this->enrolment->enrol($conference, $this->getUser())) { ... } } }
32. namespace Acme\ConferenceBundle\Controller; use Acme\Enrolment\ConferceEnrolment; class RegistrationController { public function __construct(ConferceEnrolment $enrolment) { $this->enrolment = $enrolment; } public function registerAction(Conference $conference) { $conference = $this->repository->find($id); if ($this->enrolment->enrol($conference, $this->getUser())) { ... } } } $this->container->get(‘security.context’) ->getToken()->getUser();
33. # src/Acme/ConferenceBundle/Resources/config/services.xml <service id="symfony.security.auth.token" class="%symfony.security.auth.token.class%" factory-service="security.context" factory-method="getToken"> </service> <service id="acme.learner" class="%inviqa.learner.class%" factory-service="symfony.security.auth.token" factory-method="getUser"> </service> # src/Acme/Learning/Learner.php namespace Acme\Learning; interface Learner { public function isEnrolled(); }
34. # src/Acme/ConferenceBundle/Entity/User.php namespace Acme\ConferenceBundle\Enity\User; use Acme\Learning\Learner; use Symfony\Component\Security\Core\User\UserInterface; class User implements Learner, UserInterface { ... public function isEnrolled() { ... } ... }
35. namespace Acme\ConferenceBundle\Controller; use Acme\Learning\Learner; use Acme\Enrolment\ConferceEnrolment; class RegistrationController { public function __construct( Learner $learner, ConferceEnrolment $enrolment ) { $this->learner = $learner; $this->enrolment = $enrolment; } public function registerAction(Conference $conference) { if ($this->enrolment->enrol($conference, $this->learner)) { ... } } }
36. namespace Acme\ConferenceBundle\Controller; use Acme\Learning\Learner; use Acme\Enrolment\ConferceEnrolment; class RegistrationController { public function __construct( Learner $learner; ConferceEnrolment $enrolment ) { $this->learner = $learner; $this->enrolment = $enrolment; } public function registerAction(Conference $conference) { if ($this->enrolment->enrol($conference, $this->learner)) { ... } } } Interface
37. namespace Acme\ConferenceBundle\Controller; use Acme\Learning\Learner; use Acme\Enrolment\ConferceEnrolment; use Symfony\Component\HttpFoundation\RedirectResponse; class RegistrationController { ... public function registerAction(Conference $conference) { if ($this->enrolment->enrol($conference, $this->learner)) { return new RedirectResponse(‘success’); } return new RedirectResponse(‘fail’); } }
38. namespace Acme\ConferenceBundle\Controller; use Acme\Learning\Learner; use Acme\Enrolment\ConferceEnrolment; use Symfony\Component\HttpFoundation\RedirectResponse; use Symfony\Component\Routing\RouterInterface; class RegistrationController { ... public function registerAction(Conference $conference) { if ($this->enrolment->enrol($conference, $this->learner)) { return new RedirectResponse( $this->router->generate(‘enrolment_successful’) ); } return new RedirectResponse( $this->router->generate(‘enrolment_failed’) ); } }
39. namespace Acme\ConferenceBundle\Controller; ... use Acme\Enrolment\EnrolmentNotifier; class RegistrationController { ... public function registerAction(Conference $conference) { if ($this->enrolment->enrol($conference, $this->learner)) { $this->notifier->notify($this->learner, ‘success’); return new RedirectResponse( $this->router->generate(‘enrolment_successful’)); } return new RedirectResponse( $this->router->generate(‘enrolment_failed’)); } }
40. am I happy?
41. namespace Acme\ConferenceBundle\Controller; use Acme\Learning\Learner; use Acme\Enrolment\ConferceEnrolment; use Symfony\Component\HttpFoundation\RedirectResponse; use Symfony\Component\Routing\RouterInterface; use Acme\Enrolment\EnrolmentNotifier; class RegistrationController { public function __construct( Learner $learner, ConferenceEnrolment $enrolment, EnrolmentNotifier $notifier, RouterInterface $router ) { $this->learner = $learner; $this->enrolment = $enrolment; $this->notifier = $notifier; $this->router = $router; } ... Interfaces!
42. namespace Acme\ConferenceBundle\Controller; use Acme\Learning\Learner; use Acme\Enrolment\ConferceEnrolment; use Symfony\Component\HttpFoundation\RedirectResponse; use Symfony\Component\Routing\RouterInterface; use Acme\Enrolment\EnrolmentNotifier; class RegistrationController { public function __construct( Learner $learner ConferenceEnrolment $enrolment, EnrolmentNotifier $notifier, RouterInterface $router ) { $this->learner = $learner; $this->enrolment = $enrolment; $this->notifier = $notifier; $this->router = $router; } ... Interfaces!
43. INTERFACES! I SEE INTERFACES EVERYWHERE!
44. namespace Acme\Enrolment; use Acme\Learning\Learner; use Acme\Learning\Conference; use Acme\Enrolment\ConferceEnrolment; use Acme\Enrolment\EnrolmentNotifier; class ConferenceEnrolmentHandler { public function __construct( ConferceEnrolment $enrolment, EnrolmentNotifier $notifier ) { $this->enrolment = $enrolment; $this->notifier = $notifier; } public function handle(Conference $conference, Learner $learner) { if ($this->enrolment->handle($conference, $learner)) { $this->notifier->notify($learner, ‘success’); return true; } return false; } }
45. namespace Acme\ConferenceBundle\Controller; use Acme\Learning\Learner; use Symfony\Component\HttpFoundation\RedirectResponse; use Symfony\Component\Routing\RouterInterface; use Acme\Enrolment\ConferenceEnrolmentHandler; class RegistrationController { ... public function registerAction(Conference $conference) { $route = $this->handler->handle($conference, $this->learner) ? ‘enrolment_successful’ : ‘enrolment_failed’; return new RedirectResponse( $this->router->generate($route) ); } }
46. am I happy?
47. Project Architecture Acme\Learning Acme\Enrolment Acme\ConferenceBundle Acme\EnrolmentAdapter
48. Project Architecture Acme\Learning Model Acme\Enrolment Application/Services Acme\DoctrineAdapter Doctrine Acme\EnrolmentBundle Controller/View
49. (I’ve forgotten about Doctrine!) oops!
50. # src/Acme/Conference/ConferenceRepository.php namespace Acme\Conference; interface ConferenceRepository { public function find($id); } # src/Acme/DoctrineAdapter/DoctrineConferenceAdapter.php namespace Acme\DoctrineAdapter; use Doctrine\ORM\EntityRepository; use Acme\Conference\ConferenceRepository; class DoctrineConferenceAdapter extends EntityRepository implements ConferenceRepository { // ConferenceRepository::find($id) is already implemented by EntityRepository } # src/Acme/DoctrineAdapter/Resources/mapping/conference.orm.xml <entity name="Acme\Conference\Conference" table="conferences" repository-class="Acme\DoctrineAdapter\ConferenceRepository">
51. What is Domain Driven Design?
52. What is Domain Driven Design? Changing folder structure and locations won’t #DDD your project.
53. What is Domain Driven Design? Fully understanding your domain and describing your business process using the same language as your business.
54. Layered Architecture Acme\EnrolmentBundle Acme\Enrolment Acme\Learning Acme\DoctrineAdapter User Interface Application Domain Infrastructure
55. Dependency Inversion “High level modules should not depend on lower level implementation” – Good old Uncle Bob
56. Controller Services Domain Infrastructure User Interface Dependency Inversion
57. Controller Services Domain Infrastructure User Interface Dependency Inversion Interfaces!
58. Controller Services Domain Infrastructure User Interface Dependency Inversion
59. Controller Services Domain Infrastructure User Interface Dependency Inversion Implementation detail
60. Don’t mix layers!
61. Know your domain
62. Use right tools
63. @super_marek Questions?
64. 10% discount code: SymfonyUKmeetup valid until April 25th
65. Thank you! @super_marek