Custom trans filter in Twig and Symfony2

6
votes

I need to overide standart Twig trans filter for my special purposes, e.g. I want to getting my translations from custom storage. So I dont know what I need to do. I try to figure out in docs. But there is no description about translations. I found Symfony\Bridge\Twig\Extension\TranslationExtension class and I think maybe I need only to overide this class? Thanks!

3
phpsymfonytwigtranslationtwig-extension
It would be best to create a custom loader rather than overriding the trans filter. There is an example of making on for loading from the DB here - blog.elendev.com/development/php/symfony/… - which you may be able to expand on to fit your purposes. - qooplmao
Take a look at symfony.com/doc/current/components/translation/…. You could use the existing loaders and add resources from your custom storage. - Holger
@Holger, yes, I already create my custom loader, but I dont know how use only my loader, emmm, first I load all translations from using basic loaders, then I place it in my custom storage, and I want that trans will search for translation in my storage. - nowiko
I would avoid loading different resources into one translation domain. Been there, seen this... Solved it by creating a new message domain and an overridden translator class, that switched to the default domain if no translation was found in first case. - Holger
You should post your code as an answer so people with the same problem will have a solution - Med

3 Answers

4
votes

Just to expand on @Webberig's answer above, in Symphony v3.0.4 and Twig v1.24.0, the way you define your service seems important.

I wanted to add a domain fallback capability to the default trans() filter but couldn't figure out how to override the default filter. I finally succeeded like so:

In app/config/services.yml

# This is important!! Use this exact service ID (twig.extension.trans)
twig.extension.trans:
  class: AppBundle\Twig\AppTranslationExtension
  public: false
  arguments: ['@translator']
  tags:
    - { name: twig.extension }

And that's what basically did it for me: using the same exact service ID in my config.

For the rest I just overrided the trans filter method. Here it is for those interested:

namespace AppBundle\Twig;

use Symfony\Bridge\Twig\Extension\TranslationExtension;
use Symfony\Component\Translation\TranslatorInterface;

class AppTranslationExtension extends TranslationExtension
{
    public function __construct(
            TranslatorInterface $translator, 
            \Twig_NodeVisitorInterface $translationNodeVisitor = null)
    {
        parent::__construct($translator, $translationNodeVisitor);
    }

    /**
     * {@inheritdoc}
     */
    public function getFilters()
    {
        return array(
            new \Twig_SimpleFilter('trans', array($this, 'trans')),
        );
    }

    public function trans($id, array $parameters = array(), $domain = null, $locale = null)
    {
        if (null === $locale) {
            $locale = $this->getTranslator()->getLocale();
        }

        if (null === $domain) {
            $domain = 'messages';
        }

        if ('messages' !== $domain 
        && false === $this->translationExists($id, $domain, $locale)) {
            $domain = 'messages';
        }

        return $this->getTranslator()->trans($id, $parameters, $domain, $locale);
    }

    protected function translationExists($id, $domain, $locale)
    {
        return $this->getTranslator()->getCatalogue($locale)->has((string) $id, $domain);
    }

    /**
     * {@inheritdoc}
     */
    public function getName()
    {
        return 'app_translator';
    }
}
2
votes

The Translations component of Symfony basically overrides Twig's default trans filter. The component is part of the core frameworkBundle and can't be disabled.

You can however do the same and re-override the trans filter with your own Twig extension.

Just create a Twig extension as described here: http://symfony.com/doc/current/cookbook/templating/twig_extension.html

If you add a trans filter, it will override the Translation component's code.

0
votes

To elaborate after @Webberig, you can define your own translation extension without overriding the original one (wich IMO is bad because you have to maintain at least the constructor signature) and just use the original extension as inner service and access the original trans() member function wich should be always public by definition...

# config/services.yaml
...
    App\Twig\TranslationExtension:
        arguments: ['@twig.extension.trans']
        tags:
            - { name: twig.extension, priority: 100 }
...

// src\Twig\TranslationExtension.php
namespace App\Twig;

use Symfony\Bridge\Twig\Extension\TranslationExtension as BaseTranslationExtension;
use Twig\Extension\AbstractExtension;
use Twig\TwigFilter;

class TranslationExtension extends AbstractExtension
{
    /**
     * @var BaseTranslationExtension
     */
    protected $inner;
    public function __construct(BaseTranslationExtension $inner)
    {
        $this->inner = $inner;
    }

    public function getFilters()
    {
        return [
            new TwigFilter('trans', [$this, 'trans']),
        ];
    }

    public function trans($message, array $arguments = [], $domain = null, $locale = null, $count = null)
    {
        // do ugly stuff

        return $this->inner->trans($message, $arguments, $domain, $locale, $count);
    }
}

(used against SF4.2)