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single: Console; Commands as Services

How to define Commands as Services

.. versionadded:: 2.4

Support for registering commands in the service container was added in

version 2.4.

By default, Symfony will take a look in the ``Command`` directory of your

bundles and automatically register your commands. For the ones implementing

the ``ContainerAwareCommand`` interface, Symfony will even inject the container.

While making life easier, this default implementation has some drawbacks in some

situations:

* what if you want your command to be defined elsewhere than in the ``Command``

folder?

* what if you want to register conditionally your command, depending on the

current environment or on the availability of some dependencies?

* what if you need to access dependencies before the ``setContainer`` is called

(for example in the ``configure`` method)?

* what if you want to reuse a command many times, but with different

dependencies or parameters?

To solve those problems, you can register your command as a service by simply

defining it with the ``console.command`` tag:

.. configuration-block::

.. code-block:: yaml

.. code-block:: xml

.. code-block:: php

Here are some use cases.

Use dependencies and parameters in configure

For example, imagine you want to provide a default value for the ``name``

argument. You could:

* hard code a string and pass it as the 4th argument of ``addArgument``;

* allow the user to set the default value in the configuration;

* retrieve the default value from a service (a repository for example).

With a ``ContainerAwareCommand`` you wouldn't be able to retrieve the

configuration parameter, because the ``configure`` method is called in the

command's constructor. The only solution is to inject them through its

constructor:

<?php

// 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\InputArgument;

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;

}

protected function configure()

{

$defaultName = $this->nameRepository->findLastOne();

$this

->setName('demo:greet')

->setDescription('Greet someone')

->addArgument('name', InputArgument::OPTIONAL, 'Who do you want to greet?', $defaultName)

;

}

protected function execute(InputInterface $input, OutputInterface $output)

{

$name = $input->getArgument('name');

$output->writeln($name);

}

}

commands_as_services