How to prefix URLs with the locale in Symfony

This post was originally posted by Buissartt.

Today, we'll see how to prefix our URLs with the locale we want to display the website.

How to prefix routes with a locale :

1. Add the following lines in the /config/services.yaml file. You can add every language you want there. In this example, we've added french and english, and the default one is french.

parameters:
    locale: fr
    app_locales: fr|en

2. Then, add the following lines in the /config/routes/annotations.yaml file. This will be used to prefix routes with the locales you've defined before.

controllers:
    resource: ../../src/Controller/
    type: annotation
    prefix: /{_locale}
    requirements:
      _locale: '%app_locales%'
    defaults:
      _locales: '%locale%'

3. Then, create a .htaccess file in the /public/ folder, with this content. This is used to rewrite the URLs with the prefix.

# Use the front controller as index file. It serves as a fallback solution when
# every other rewrite/redirect fails (e.g. in an aliased environment without
# mod_rewrite). Additionally, this reduces the matching process for the
# start page (path "/") because otherwise Apache will apply the rewriting rules
# to each configured DirectoryIndex file (e.g. index.php, index.html, index.pl).
DirectoryIndex index.php

# By default, Apache does not evaluate symbolic links if you did not enable this
# feature in your server configuration. Uncomment the following line if you
# install assets as symlinks or if you experience problems related to symlinks
# when compiling LESS/Sass/CoffeScript assets.
# Options +FollowSymlinks

# Disabling MultiViews prevents unwanted negotiation, e.g. "/index" should not resolve
# to the front controller "/index.php" but be rewritten to "/index.php/index".
<IfModule mod_negotiation.c>
    Options -MultiViews
</IfModule>

<IfModule mod_rewrite.c>
    RewriteEngine On

    # Determine the RewriteBase automatically and set it as environment variable.
    # If you are using Apache aliases to do mass virtual hosting or installed the
    # project in a subdirectory, the base path will be prepended to allow proper
    # resolution of the index.php file and to redirect to the correct URI. It will
    # work in environments without path prefix as well, providing a safe, one-size
    # fits all solution. But as you do not need it in this case, you can comment
    # the following 2 lines to eliminate the overhead.
    RewriteCond %{REQUEST_URI}::$0 ^(/.+)/(.*)::\2$
    RewriteRule .* - [E=BASE:%1]

    # Sets the HTTP_AUTHORIZATION header removed by Apache
    RewriteCond %{HTTP:Authorization} .+
    RewriteRule ^ - [E=HTTP_AUTHORIZATION:%0]

    # Redirect to URI without front controller to prevent duplicate content
    # (with and without `/index.php`). Only do this redirect on the initial
    # rewrite by Apache and not on subsequent cycles. Otherwise we would get an
    # endless redirect loop (request -> rewrite to front controller ->
    # redirect -> request -> ...).
    # So in case you get a "too many redirects" error or you always get redirected
    # to the start page because your Apache does not expose the REDIRECT_STATUS
    # environment variable, you have 2 choices:
    # - disable this feature by commenting the following 2 lines or
    # - use Apache >= 2.3.9 and replace all L flags by END flags and remove the
    #   following RewriteCond (best solution)
    RewriteCond %{ENV:REDIRECT_STATUS} =""
    RewriteRule ^index\.php(?:/(.*)|$) %{ENV:BASE}/$1 [R=301,L]

    # If the requested filename exists, simply serve it.
    # We only want to let Apache serve files and not directories.
    # Rewrite all other queries to the front controller.
    RewriteCond %{REQUEST_FILENAME} !-f
    RewriteRule ^ %{ENV:BASE}/index.php [L]
</IfModule>

<IfModule !mod_rewrite.c>
    <IfModule mod_alias.c>
        # When mod_rewrite is not available, we instruct a temporary redirect of
        # the start page to the front controller explicitly so that the website
        # and the generated links can still be used.
        RedirectMatch 307 ^/$ /index.php/
        # RedirectTemp cannot be used instead
    </IfModule>
</IfModule>

4. Now, add the following lines in the /config/routes/routes.yaml file to redirect the default route to the RedirectController :

redirect:
   path: /
   controller: App\Controller\RedirectController::redirectToLocale

5. You now need to create the RedirectController with the command php bin/console make:controller, and add this content :

<?php

namespace App\Controller;

use Symfony\Bundle\FrameworkBundle\Controller\AbstractController;
use Symfony\Component\Routing\Annotation\Route;
use Symfony\Component\HttpFoundation\Response;

class RedirectController extends AbstractController
{
    public function redirectToLocale(): Response
    {
        return $this->redirectToRoute('app_index');
    }
}

6. Then, you just need to choose the default local il the /config/packages/translations.yaml file !

It should now be fully functionnal !