How to access an application parameters from a service?

Question

From my controllers, I access the application parameters (those in /app/config) with

$this->container->getParameter('my_param')

But I don't know how to access it from a service (I imagine my service class is not supposed to extend Symfony\Bundle\FrameworkBundle\Controller\Controller).

Should I map needed parameters into my service registration like this:

#src/Me/MyBundle/Service/my_service/service.yml
parameters:
    my_param1: %my_param1%
    my_param2: %my_param2%
    my_param3: %my_param3%

or something similar? How should I access to my application parameters from a service?

---

This question seems like the same but mine actually answers to it (parameters from a controller), I'm talking about accessing from a service.

Answer 1

You can pass parameters to your service in the same way as you inject other services, by specifying them in your service definition. For example, in YAML:

services:
    my_service:
        class:  My\Bundle\Service\MyService
        arguments: [%my_param1%, %my_param2%]

where the %my_param1% etc corresponds to a parameter named my_param1. Then your service class constructor could then be:

public function __construct($myParam1, $myParam2)
{
    // ...
}

Answer 2

The Clean Way 2018

Since 2018 and Symfony 3.4 there is much cleaner way - easy to setup and use.

Instead of using container and service/parameter locator anti-pattern, you can pass parameters to class via it's constructor. Don't worry, it's not time-demanding work, but rather setup once & forget approach.

How to set it up in 2 steps?

1. config.yml

# config.yml
parameters:
    api_pass: 'secret_password'
    api_user: 'my_name'

services:
    _defaults:
        autowire: true
        bind:
            $apiPass: '%api_pass%'
            $apiUser: '%api_user%'

    App\:
        resource: ..

2. Any Controller

<?php declare(strict_types=1);

final class ApiController extends SymfonyController
{
    /**
     * @var string 
     */
    private $apiPass;

    /**
     * @var string
     */
    private $apiUser;

    public function __construct(string $apiPass, string $apiUser)
    {
        $this->apiPass = $apiPass;
        $this->apiUser = $apiUser;
    }

    public function registerAction(): void
    {
        var_dump($this->apiPass); // "secret_password"
        var_dump($this->apiUser); // "my_name"
    }
}

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This is called constructor injection over services locator approach.

To read more about this, check my post How to Get Parameter in Symfony Controller the Clean Way.

(It's tested and I keep it updated for new Symfony major version (5, 6...)).

Answer 3

There is a very clean new way to achieve it since symfony 4.1

<?php
// src/Service/MessageGeneratorService.php

use Symfony\Component\DependencyInjection\ParameterBag\ParameterBagInterface;

class MessageGeneratorService
{
 private $params;
 public function __construct(ParameterBagInterface $params)
 {
      $this->params = $params;
 }
 public function someMethod()
 {
     $parameterValue = $this->params->get('parameter_name');
...
 }
}

source : https://symfony.com/blog/new-in-symfony-4-1-getting-container-parameters-as-a-service.