Symfony2 global functions

Question

For example i have algorithmic function, which calculates specific hash-code. Function itself is 300+ lines of code. I need to use that functions many times in many different controllers in my bundle. Where can i store my calculate_hash() to use it in my bundle ? Can i access it from other bundles ? Can i also write global calculate_hash() which have access to entity manager ?

Didn't find my answer here.

Answer 1

In the Symfony2 world, this is clearly belonging to a service. Services are in fact normal classes that are tied to the dependency injection container. You can inject them the dependencies you need. For example, say your class where the function calculate_hash is located is AlgorithmicHelper. The service holds "global" functions. You define your class something like this:

namespace Acme\AcmeBundle\Helper;

// Correct use statements here ...

class AlgorithmicHelper {

    private $entityManager;

    public function __construct(EntityManager $entityManager) {
        $this->entityManager = $entityManager;
    }

    public function calculate_hash() {
        // Do what you need, $this->entityManager holds a reference to your entity manager
    }
}

This class then needs to be made aware to symfony dependecy container. For this, you define you service in the app/config/config.yml files by adding a service section like this:

services:
  acme.helper.algorithmic:
    class: Acme\AcmeBundle\Helper\AlgorithmicHelper
    arguments:
      entityManager: "@doctrine.orm.entity_manager"

Just below the service, is the service id. It is used to retrieve your service in the controllers for example. After, you specify the class of the service and then, the arguments to pass to the constructor of the class. The @ notation means pass a reference to the service with id doctrine.orm.entity_manager.

Then, in your controller, you do something like this to retrieve the service and used it:

$helper = $this->get('acme.helper.algorithmic');
$helper-> calculate_hash();

Note that the result of the call to $this->get('acme.helper.algorithmic') will always return the same instance of the helper. This means that, by default, service are unique. It is like having a singleton class.

For further details, I invite you to read the Symfony2 book. Check those links also

1. The service container section from Symfony2 book.
2. An answer I gave on accesing service outside controllers, here.

Hope it helps.

Regards,
Matt

Answer 2

Braian in comment asked for Symfony 3 answer, so here is one Symfony 3.3 (released May 2017):

1. The original class remains the same

namespace Acme\AcmeBundle\Helper;

use Doctrine\ORM\EntityManager;

final class AlgorithmicHelper
{
    /**
     * @var EntityManager
     */
    private $entityManager;

    public function __construct(EntityManager $entityManager)
    {
        $this->entityManager = $entityManager;
    }

    public function calculateHash()
    {
        // Do what you need, $this->entityManager holds a reference to your entity manager
    }
}

2. Service registration is much simpler

# app/config/services.yml
services:
    _defaults: autowire # this enabled constructor autowiring for all registered services

    Acme\AcmeBundle\Helper\AlgorithmicHelper: ~

3. Use constructor injection to get the service

use Acme\AcmeBundle\Helper\AlgorithmicHelper;

class SomeController
{
    /**
     * @var AlgorithmicHelper
     */
    private $algorithmicHelper;

    public function __construct(AlgorithmicHelper $algorithmicHelper)  
    {
        $this->algorithmicHelper = $algorithmicHelper;
    }

    public function someAction()
    {
        // some code
        $hash = $this->algorithmicHelper->calculateHash();
        // some code
    }
}

You can read about Symfony 3.3 dependency injection (in this case registering services in config and using it in controller) news in these 2 posts:

• https://www.tomasvotruba.cz/blog/2017/05/07/how-to-refactor-to-new-dependency-injection-features-in-symfony-3-3/
• https://symfony.com/blog/the-new-symfony-3-3-service-configuration-changes-explained