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Translations

The term "internationalization" (often abbreviated i18n) refers to the process of abstracting strings and other locale-specific pieces out of your application into a layer where they can be translated and converted based on the user's locale (i.e. language and country). For text, this means wrapping each with a function capable of translating the text (or "message") into the language of the user:

// text will *always* print out in English
dump('Hello World');
die();

// text can be translated into the end-user's language or
// default to English
dump($translator->trans('Hello World'));
die();

Note

The term locale refers roughly to the user's language and country. It can be any string that your application uses to manage translations and other format differences (e.g. currency format). The ISO 639-1 language code, an underscore (_), then the ISO 3166-1 alpha-2 country code (e.g. fr_FR for French/France) is recommended.

In this chapter, you'll learn how to use the Translation component in the Symfony Framework. You can read the :doc:`Translation component documentation </components/translation/usage>` to learn even more. Overall, the process has several steps:

  1. :ref:`Enable and configure <book-translation-configuration>` Symfony's translation service;
  2. Abstract strings (i.e. "messages") by wrapping them in calls to the Translator (":ref:`book-translation-basic`");
  3. :ref:`Create translation resources/files <book-translation-resources>` for each supported locale that translate each message in the application;
  4. Determine, :ref:`set and manage the user's locale <book-translation-user-locale>` for the request and optionally :doc:`on the user's entire session </cookbook/session/locale_sticky_session>`.

Configuration

Translations are handled by a translator :term:`service` that uses the user's locale to lookup and return translated messages. Before using it, enable the translator in your configuration:

See :ref:`book-translation-fallback` for details on the fallbacks key and what Symfony does when it doesn't find a translation.

The locale used in translations is the one stored on the request. This is typically set via a _locale attribute on your routes (see :ref:`book-translation-locale-url`).

Basic Translation

Translation of text is done through the translator service (:class:`Symfony\\Component\\Translation\\Translator`). To translate a block of text (called a message), use the :method:`Symfony\\Component\\Translation\\Translator::trans` method. Suppose, for example, that you're translating a simple message from inside a controller:

// ...
use Symfony\Component\HttpFoundation\Response;

public function indexAction()
{
    $translated = $this->get('translator')->trans('Symfony is great');

    return new Response($translated);
}

When this code is executed, Symfony will attempt to translate the message "Symfony is great" based on the locale of the user. For this to work, you need to tell Symfony how to translate the message via a "translation resource", which is usually a file that contains a collection of translations for a given locale. This "dictionary" of translations can be created in several different formats, XLIFF being the recommended format:

For information on where these files should be located, see :ref:`book-translation-resource-locations`.

Now, if the language of the user's locale is French (e.g. fr_FR or fr_BE), the message will be translated into J'aime Symfony. You can also translate the message inside your :ref:`templates <book-translation-tags>`.

The Translation Process

To actually translate the message, Symfony uses a simple process:

  • The locale of the current user, which is stored on the request is determined;
  • A catalog (e.g. big collection) of translated messages is loaded from translation resources defined for the locale (e.g. fr_FR). Messages from the :ref:`fallback locale <book-translation-fallback>` are also loaded and added to the catalog if they don't already exist. The end result is a large "dictionary" of translations.
  • If the message is located in the catalog, the translation is returned. If not, the translator returns the original message.

When using the trans() method, Symfony looks for the exact string inside the appropriate message catalog and returns it (if it exists).

Message Placeholders

Sometimes, a message containing a variable needs to be translated:

use Symfony\Component\HttpFoundation\Response;

public function indexAction($name)
{
    $translated = $this->get('translator')->trans('Hello '.$name);

    return new Response($translated);
}

However, creating a translation for this string is impossible since the translator will try to look up the exact message, including the variable portions (e.g. "Hello Ryan" or "Hello Fabien").

For details on how to handle this situation, see :ref:`component-translation-placeholders` in the components documentation. For how to do this in templates, see :ref:`book-translation-tags`.

Pluralization

Another complication is when you have translations that may or may not be plural, based on some variable:

There is one apple.
There are 5 apples.

To handle this, use the :method:`Symfony\\Component\\Translation\\Translator::transChoice` method or the transchoice tag/filter in your :ref:`template <book-translation-tags>`.

For much more information, see :ref:`component-translation-pluralization` in the Translation component documentation.

Translations in Templates

Most of the time, translation occurs in templates. Symfony provides native support for both Twig and PHP templates.

Twig Templates

Symfony provides specialized Twig tags (trans and transchoice) to help with message translation of static blocks of text:

{% trans %}Hello %name%{% endtrans %}

{% transchoice count %}
    {0} There are no apples|{1} There is one apple|]1,Inf[ There are %count% apples
{% endtranschoice %}

The transchoice tag automatically gets the %count% variable from the current context and passes it to the translator. This mechanism only works when you use a placeholder following the %var% pattern.

Caution!

The %var% notation of placeholders is required when translating in Twig templates using the tag.

Tip

If you need to use the percent character (%) in a string, escape it by doubling it: {% trans %}Percent: %percent%%%{% endtrans %}

You can also specify the message domain and pass some additional variables:

{% trans with {'%name%': 'Fabien'} from "app" %}Hello %name%{% endtrans %}

{% trans with {'%name%': 'Fabien'} from "app" into "fr" %}Hello %name%{% endtrans %}

{% transchoice count with {'%name%': 'Fabien'} from "app" %}
    {0} %name%, there are no apples|{1} %name%, there is one apple|]1,Inf[ %name%, there are %count% apples
{% endtranschoice %}

The trans and transchoice filters can be used to translate variable texts and complex expressions:

{{ message|trans }}

{{ message|transchoice(5) }}

{{ message|trans({'%name%': 'Fabien'}, "app") }}

{{ message|transchoice(5, {'%name%': 'Fabien'}, 'app') }}

Tip

Using the translation tags or filters have the same effect, but with one subtle difference: automatic output escaping is only applied to translations using a filter. In other words, if you need to be sure that your translated message is not output escaped, you must apply the raw filter after the translation filter:

{# text translated between tags is never escaped #}
{% trans %}
    <h3>foo</h3>
{% endtrans %}

{% set message = '<h3>foo</h3>' %}

{# strings and variables translated via a filter are escaped by default #}
{{ message|trans|raw }}
{{ '<h3>bar</h3>'|trans|raw }}

Tip

You can set the translation domain for an entire Twig template with a single tag:

{% trans_default_domain "app" %}

Note that this only influences the current template, not any "included" template (in order to avoid side effects).

PHP Templates

The translator service is accessible in PHP templates through the translator helper:

<?php echo $view['translator']->trans('Symfony is great') ?>

<?php echo $view['translator']->transChoice(
    '{0} There are no apples|{1} There is one apple|]1,Inf[ There are %count% apples',
    10,
    array('%count%' => 10)
) ?>

Translation Resource/File Names and Locations

Symfony looks for message files (i.e. translations) in the following default locations:

  • the app/Resources/translations directory;
  • the app/Resources/<bundle name>/translations directory;
  • the Resources/translations/ directory inside of any bundle.

The locations are listed here with the highest priority first. That is, you can override the translation messages of a bundle in any of the top 2 directories.

The override mechanism works at a key level: only the overridden keys need to be listed in a higher priority message file. When a key is not found in a message file, the translator will automatically fall back to the lower priority message files.

The filename of the translation files is also important: each message file must be named according to the following path: domain.locale.loader:

  • domain: An optional way to organize messages into groups (e.g. admin, navigation or the default messages) - see :ref:`using-message-domains`;
  • locale: The locale that the translations are for (e.g. en_GB, en, etc);
  • loader: How Symfony should load and parse the file (e.g. xlf, php, yml, etc).

The loader can be the name of any registered loader. By default, Symfony provides many loaders, including:

  • xlf: XLIFF file;
  • php: PHP file;
  • yml: YAML file.

The choice of which loader to use is entirely up to you and is a matter of taste. The recommended option is to use xlf for translations. For more options, see :ref:`component-translator-message-catalogs`.

Note

You can add other directories with the paths option in the configuration:

Note

You can also store translations in a database, or any other storage by providing a custom class implementing the :class:`Symfony\\Component\\Translation\\Loader\\LoaderInterface` interface. See the :ref:`dic-tags-translation-loader` tag for more information.

Caution!

Each time you create a new translation resource (or install a bundle that includes a translation resource), be sure to clear your cache so that Symfony can discover the new translation resources:

$ php bin/console cache:clear

Fallback Translation Locales

Imagine that the user's locale is fr_FR and that you're translating the key Symfony is great. To find the French translation, Symfony actually checks translation resources for several locales:

  1. First, Symfony looks for the translation in a fr_FR translation resource (e.g. messages.fr_FR.xlf);
  2. If it wasn't found, Symfony looks for the translation in a fr translation resource (e.g. messages.fr.xlf);
  3. If the translation still isn't found, Symfony uses the fallbacks configuration parameter, which defaults to en (see Configuration).

Note

When Symfony doesn't find a translation in the given locale, it will add the missing translation to the log file. For details, see :ref:`reference-framework-translator-logging`.

Handling the User's Locale

The locale of the current user is stored in the request and is accessible via the request object:

use Symfony\Component\HttpFoundation\Request;

public function indexAction(Request $request)
{
    $locale = $request->getLocale();
}

To set the user's locale, you may want to create a custom event listener so that it's set before any other parts of the system (i.e. the translator) need it:

public function onKernelRequest(GetResponseEvent $event)
{
    $request = $event->getRequest();

    // some logic to determine the $locale
    $request->getSession()->set('_locale', $locale);
}

Read :doc:`/cookbook/session/locale_sticky_session` for more on the topic.

Note

Setting the locale using $request->setLocale() in the controller is too late to affect the translator. Either set the locale via a listener (like above), the URL (see next) or call setLocale() directly on the translator service.

See the :ref:`book-translation-locale-url` section below about setting the locale via routing.

The Locale and the URL

Since you can store the locale of the user in the session, it may be tempting to use the same URL to display a resource in different languages based on the user's locale. For example, http://www.example.com/contact could show content in English for one user and French for another user. Unfortunately, this violates a fundamental rule of the Web: that a particular URL returns the same resource regardless of the user. To further muddy the problem, which version of the content would be indexed by search engines?

A better policy is to include the locale in the URL. This is fully-supported by the routing system using the special _locale parameter:

When using the special _locale parameter in a route, the matched locale will automatically be set on the Request and can be retrieved via the :method:`Symfony\\Component\\HttpFoundation\\Request::getLocale` method. In other words, if a user visits the URI /fr/contact, the locale fr will automatically be set as the locale for the current request.

You can now use the locale to create routes to other translated pages in your application.

Tip

Read :doc:`/cookbook/routing/service_container_parameters` to learn how to avoid hardcoding the _locale requirement in all your routes.

Setting a Default Locale

What if the user's locale hasn't been determined? You can guarantee that a locale is set on each user's request by defining a default_locale for the framework:

Translating Constraint Messages

If you're using validation constraints with the Form component, then translating the error messages is easy: simply create a translation resource for the validators :ref:`domain <using-message-domains>`.

To start, suppose you've created a plain-old-PHP object that you need to use somewhere in your application:

// src/AppBundle/Entity/Author.php
namespace AppBundle\Entity;

class Author
{
    public $name;
}

Add constraints through any of the supported methods. Set the message option to the translation source text. For example, to guarantee that the $name property is not empty, add the following:

Create a translation file under the validators catalog for the constraint messages, typically in the Resources/translations/ directory of the bundle.

Translating Database Content

The translation of database content should be handled by Doctrine through the Translatable Extension or the Translatable Behavior (PHP 5.4+). For more information, see the documentation for these libraries.

Debugging Translations

When maintaining a bundle, you may use or remove the usage of a translation message without updating all message catalogues. The debug:translation command helps you to find these missing or unused translation messages for a given locale. It shows you a table with the result when translating the message in the given locale and the result when the fallback would be used. On top of that, it also shows you when the translation is the same as the fallback translation (this could indicate that the message was not correctly translated).

Thanks to the messages extractors, the command will detect the translation tag or filter usages in Twig templates:

{% trans %}Symfony2 is great{% endtrans %}

{{ 'Symfony2 is great'|trans }}

{{ 'Symfony2 is great'|transchoice(1) }}

{% transchoice 1 %}Symfony2 is great{% endtranschoice %}

It will also detect the following translator usages in PHP templates:

$view['translator']->trans("Symfony2 is great");

$view['translator']->transChoice('Symfony2 is great', 1);

Caution!

The extractors are not able to inspect the messages translated outside templates which means that translator usages in form labels or inside your controllers won't be detected. Dynamic translations involving variables or expressions are not detected in templates, which means this example won't be analyzed:

{% set message = 'Symfony2 is great' %}
{{ message|trans }}

Suppose your application's default_locale is fr and you have configured en as the fallback locale (see :ref:`book-translation-configuration` and :ref:`book-translation-fallback` for how to configure these). And suppose you've already setup some translations for the fr locale inside an AcmeDemoBundle:

and for the en locale:

To inspect all messages in the fr locale for the AcmeDemoBundle, run:

$ php bin/console debug:translation fr AcmeDemoBundle

You will get this output:

/images/book/translation/debug_1.png

It indicates that the message Symfony2 is great is unused because it is translated, but you haven't used it anywhere yet.

Now, if you translate the message in one of your templates, you will get this output:

/images/book/translation/debug_2.png

The state is empty which means the message is translated in the fr locale and used in one or more templates.

If you delete the message Symfony2 is great from your translation file for the fr locale and run the command, you will get:

/images/book/translation/debug_3.png

The state indicates the message is missing because it is not translated in the fr locale but it is still used in the template. Moreover, the message in the fr locale equals to the message in the en locale. This is a special case because the untranslated message id equals its translation in the en locale.

If you copy the content of the translation file in the en locale, to the translation file in the fr locale and run the command, you will get:

/images/book/translation/debug_4.png

You can see that the translations of the message are identical in the fr and en locales which means this message was probably copied from French to English and maybe you forgot to translate it.

By default all domains are inspected, but it is possible to specify a single domain:

$ php bin/console debug:translation en AcmeDemoBundle --domain=messages

When bundles have a lot of messages, it is useful to display only the unused or only the missing messages, by using the --only-unused or --only-missing switches:

$ php bin/console debug:translation en AcmeDemoBundle --only-unused
$ php bin/console debug:translation en AcmeDemoBundle --only-missing

Summary

With the Symfony Translation component, creating an internationalized application no longer needs to be a painful process and boils down to just a few basic steps:

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