feature #3889 Fixed the section about getting services from a command…

… (javiereguiluz)

This PR was merged into the 2.3 branch.

Discussion
----------

Fixed the section about getting services from a command

| Q             | A
| ------------- | ---
| Doc fix?      | no
| New docs?     | yes
| Applies to    | 2.3+
| Fixed tickets | #890

Hopefully this PR fixes one of the oldest errors of the Symfony documentation.

Commits
-------

8993beb Linked the cookbook about DIC scopes
0f3c218 Fixed the section about getting services from a command

cookbook/console/console_command.rst

@@ -68,8 +68,27 @@ Getting Services from the Service Container
 By using :class:`Symfony\\Bundle\\FrameworkBundle\\Command\\ContainerAwareCommand`
 as the base class for the command (instead of the more basic
 :class:`Symfony\\Component\\Console\\Command\\Command`), you have access to the
-service container. In other words, you have access to any configured service.
-For example, you could easily extend the task to be translatable::
+service container. In other words, you have access to any configured service::
+
+    protected function execute(InputInterface $input, OutputInterface $output)
+    {
+        $name = $input->getArgument('name');
+        $logger = $this->getContainer()->get('logger');
+
+        $logger->info('Executing command for '.$name);
+        // ...
+    }
+
+However, due to the `container scopes </cookbook/service_container/scopes>`_ this
+code doesn't work for some services. For instance, if you try to get the ``request``
+service or any other service related to it, you'll get the following error:
+
+.. code-block:: text
+
+    You cannot create a service ("request") of an inactive scope ("request").
+
+Consider the following example that uses the ``translator`` service to
+translate some contents using a console command::
 
     protected function execute(InputInterface $input, OutputInterface $output)
     {
@@ -82,6 +101,43 @@ For example, you could easily extend the task to be translatable::
         }
     }
 
+If you dig into the Translator component classes, you'll see that the ``request``
+service is required to get the locale into which the contents are translated::
+
+    // vendor/symfony/symfony/src/Symfony/Bundle/FrameworkBundle/Translation/Translator.php
+    public function getLocale()
+    {
+        if (null === $this->locale && $this->container->isScopeActive('request')
+            && $this->container->has('request')) {
+            $this->locale = $this->container->get('request')->getLocale();
+        }
+
+        return $this->locale;
+    }
+
+Therefore, when using the ``translator`` service inside a command, you'll get the
+previous *"You cannot create a service of an inactive scope"* error message.
+The solution in this case is as easy as setting the locale value explicitly
+before translating contents::
+
+    protected function execute(InputInterface $input, OutputInterface $output)
+    {
+        $name = $input->getArgument('name');
+        $locale = $input->getArgument('locale');
+
+        $translator = $this->getContainer()->get('translator');
+        $translator->setLocale($locale);
+
+        if ($name) {
+            $output->writeln($translator->trans('Hello %name%!', array('%name%' => $name)));
+        } else {
+            $output->writeln($translator->trans('Hello!'));
+        }
+    }
+
+However for other services the solution might be more complex. For more details,
+see :doc:`/cookbook/service_container/scopes`.
+
 Testing Commands
 ----------------