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How to Define Commands as Services

2.4 version
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How to Define Commands as Services

New in version 2.4: Support for registering commands in the service container was introduced in Symfony 2.4.

By default, Symfony will take a look in the Command directory of each bundle and automatically register your commands. If a command extends the Symfony\Bundle\FrameworkBundle\Command\ContainerAwareCommand, Symfony will even inject the container. While making life easier, this has some limitations:

  • Your command must live in the Command directory;
  • There’s no way to conditionally register your service based on the environment or availability of some dependencies;
  • You can’t access the container in the configure() method (because setContainer hasn’t been called yet);
  • You can’t use the same class to create many commands (i.e. each with different configuration).

To solve these problems, you can register your command as a service and tag it with console.command:

  • YAML
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    # app/config/config.yml
    services:
        acme_hello.command.my_command:
            class: Acme\HelloBundle\Command\MyCommand
            tags:
                -  { name: console.command }
    
  • XML
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    <!-- app/config/config.xml -->
    <?xml version="1.0" encoding="UTF-8" ?>
    <container xmlns="http://symfony.com/schema/dic/services"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:schemaLocation="http://symfony.com/schema/dic/services http://symfony.com/schema/dic/services/services-1.0.xsd">
    
        <services>
            <service id="acme_hello.command.my_command"
                class="Acme\HelloBundle\Command\MyCommand">
                <tag name="console.command" />
            </service>
        </services>
    </container>
    
  • PHP
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    // app/config/config.php
    $container
        ->register('acme_hello.command.my_command', 'Acme\HelloBundle\Command\MyCommand')
        ->addTag('console.command')
    ;
    

Using Dependencies and Parameters to Set Default Values for Options

Imagine you want to provide a default value for the name option. You could pass one of the following as the 5th argument of addOption():

  • a hardcoded string;
  • a container parameter (e.g. something from parameters.yml);
  • a value computed by a service (e.g. a repository).

By extending ContainerAwareCommand, only the first is possible, because you can’t access the container inside the configure() method. Instead, inject any parameter or service you need into the constructor. For example, suppose you have some NameRepository service that you’ll use to get your default value:

// src/Acme/DemoBundle/Command/GreetCommand.php
namespace Acme\DemoBundle\Command;

use Acme\DemoBundle\Entity\NameRepository;
use Symfony\Component\Console\Command\Command;
use Symfony\Component\Console\Input\InputInterface;
use Symfony\Component\Console\Input\InputOption;
use Symfony\Component\Console\Output\OutputInterface;

class GreetCommand extends Command
{
    protected $nameRepository;

    public function __construct(NameRepository $nameRepository)
    {
        $this->nameRepository = $nameRepository;

        parent::__construct();
    }

    protected function configure()
    {
        $defaultName = $this->nameRepository->findLastOne();

        $this
            ->setName('demo:greet')
            ->setDescription('Greet someone')
            ->addOption('name', '-n', InputOption::VALUE_REQUIRED, 'Who do you want to greet?', $defaultName)
        ;
    }

    protected function execute(InputInterface $input, OutputInterface $output)
    {
        $name = $input->getOption('name');

        $output->writeln($name);
    }
}

Now, just update the arguments of your service configuration like normal to inject the NameRepository. Great, you now have a dynamic default value!

Caution

Be careful not to actually do any work in configure (e.g. make database queries), as your code will be run, even if you’re using the console to execute a different command.

This work, including the code samples, is licensed under a Creative Commons BY-SA 3.0 license.