Symfony - 在哪里放置多个/所有控制器的通用代码？

Question

Let's say my app has multiple pages like

• /home
• /settings
• /blog

For all these I need some common code. Example: Fetching the E-Mail-Address from a logged in user to show it on the top-right of each page, next to a logout button.

So on each and every controller (HomeController, SettingsController, BlogController) I would have to register a twig variable:

eg: AppBundle/Controller/HomeController.php

public function indexAction()
{
    $user_email = Something::getUserEmail();
    ...
    return $this->render('home/index.html.twig', array('user_email' => $user_email));
}

So the getUserEmail() (and probably a lot more business logic) will be the same on all front end controller methods of my app. It would be very redundant to copy the code into each controller method that renders a page. I could register a service but I would have to call it on every controller too. I could also write a BaseController with - let's say BaseController->init() - but again, I would have to call this method on every controller method over and over.

So what is the best practice to place common business logic for multiple/all controllers?

Bonus: can I "pre-register" twig variables like in smarty or do I have to submit them via render ? It would be nice to register $user_email only once and not on each controller method as this would again lead to a lot of duplicate code.

Asking for Symfony 3+, 4.

Answer 1

TL;DR: don't make your controller 'fat' and use Dependency Injection instead.

I'm using Symfony for years and I had the same question for a long time. This article is worth reading. By using many third party libraries and bundles, I saw a common way where to place business logic.

Here's an example of the directory structure of one of my bundles:

Appbundle\
    Command
    Controller
    DataFixtures
    Datatables
    Entity
    EventListener
    Exception
    Extension
    Form
    Menu
    Resources\
         views
    Security\
         Authorization\
             Voter
    Template
    Util
    Validator

(not all directories are mentioned)

An important part of the business logic is in Entity , while the security rules (mainly SecurityVoters) is in Security\\Authorization\\Voter .

For business logic that is not tightly coupled to Symfony Components or Doctrine (like Forms, SecurityVoters and my entity model) I create classes for a specific goal (keeping Single responsibility principle in mind) and use Services/ Dependency Injection to use the business logic in my controller:

use AppBundle\Mailer\Something;

// ...
public function indexAction()
{
    $mailer = $this->get(Something::class);

    $user_email = $mailer->getUserEmail();

    ...
    return $this->render('home/index.html.twig', array('user_email' => $user_email));
}

One important rule: keep your controller slim . It has only one purpose: getting a Request and send back a Response. Keeping your controllers as slim as possible has a lot of advantages:

• It makes unit tests easier. Testing services is a lot easier than testing controllers.
• You can use the same business logic in your Commands too. After my application got more complicated, I learned that not all things my application did was necessarily initiated by the front controller. For example background tasks: they are initiated by a cron job.
• If you want to have a second front controller (a RESTfull API for your native app/third party access/etc.) you can reuse the services. If you want to switch to another framework you can easily switch and use the Symfony Components too.

For you question about Twig variables, check How to Inject Variables into all Templates (ie global Variables) .

Answer 2

Have you try the Traits ? according to the docs

A Trait is intended to reduce some limitations of single inheritance by enabling a developer to reuse sets of methods freely in several independent classes

A Trait is similar to a class, but only intended to group functionality in a fine-grained and consistent way

If you does not want Injection or Services this would be a good idea. Symfony is using this approach to.

abstract class Controller implements ContainerAwareInterface
{
    use ContainerAwareTrait;
    use ControllerTrait;
....
}

You could check both traits and give it a try.

Hope it helps

Answer 3

If I understood you correctly, you can use standard controller and twig possibilities to achieve this goal. You can create a controller for common actions like rendering an email of logged-in user, and then - in "base.html.twig" - render action's result.

// CommonController.php

/**
 * @Route("/common/get-email", name="get_email")
 */
public function getEmail()
{
    // ... fetch email in some way ...
    return $this->render('home/index.html.twig', array('user_email' => $user_email));
}

// base.html.twig

{{ render(url('get_email')) }}

Please, consider the Embedding Controllers section.