How to use gettext with Twig templates in Slim Framework?

Question

I'm working with Slim 4 Framework with a Twig engine for templates.

Some time ago, Twig had an extension with {% trans %} tokens and |trans filter directly linked to gettext function.

Now things seems to be more complicated, Twig is linked to a Symfony Translator... do you know how can I link Twig to gettext?

I tried to create a custom filter, and it works, but I don't know how to create a tokenparser just to call gettext() function.

Answer 1

The "official" way would be to use the Twig-Bridge component that provides a Twig 3 TranslationExtension to translate messages with the trans filter. For this, you have to install the Symfony translator component.

The TranslationExtension can be configured with a custom Translator that must implement the TranslatorInterface. The Symfony Translator is able to use mo files as source. So you don't have to use the gettext extension anymore.

use Symfony\Bridge\Twig\Extension\TranslationExtension;
use Symfony\Component\Translation\Translator;
use Symfony\Component\Translation\Formatter\MessageFormatter;
use Symfony\Component\Translation\IdentityTranslator;
use Symfony\Component\Translation\Loader\MoFileLoader;
use Slim\Views\Twig;
// ...

$twig = Twig::create($paths, $options);

$translator = new Translator(
    'en_US',
    new MessageFormatter(new IdentityTranslator())
);

$translator->addLoader('mo', new MoFileLoader());
$twig->addExtension(new TranslationExtension($translator));

If you still want to use the gettext function, you could also try to create a custom Twig function:

https://symfony.com/doc/current/templating/twig_extension.html

use Twig\TwigFunction;

$environment = $twig->getEnvironment();

$environment->addFunction(new TwigFunction('__', function ($message) {
    return __($message);
}));

Usage

{{ __('Hello world') }}

The downside of the second approach is that you need a custom text parser.

Answer 2

I have solved adding this dependency to composer:

twig/extensions

And this extension to Twig config:

 $twig = Twig::create($twigSettings['path'], $twigSettings['settings']);
 $twig->addExtension(new I18nExtension());