Redirect route to language prefix in Symfony 4

Question

Since version 4.1, Symfony now handles multilingual routing without the need of an external plugin ( https://symfony.com/blog/new-in-symfony-4-1-internationalized-routing ). I've translated my routes with success and all works fine except that when accessing the root url ("/"), Symfony renders a 404 error instead of redirecting to a language folder such as "/en/".

I've done some research but most of what i've found is very outdated (mostly Symfony 2). Also ran into this Symfony 3 Redirect All Routes To Current Locale Version but it seems like an incredibly tedious solution to such a simple problem.

Ideally, i'd also like to redirect the url "/admin" to "/en/admin", but if i can't achieve it i can live with that.

Here's my routes/annotations.yaml file:

controllers:
    resource: ../../src/Controller/
    type: annotation
    prefix:
        fr: '/fr'
        en: '/en'
        de: '/de'

My translations .yaml file:

framework:
#default_locale: '%locale%'
default_locale: 'en'
translator:
    paths:
        - '%kernel.project_dir%/translations'
    fallbacks:
        - 'en'

Home route configuration:

@Route("/", name="home")

Answer 1

It looks like you don't have a route matching / , probably because all your routes are prefixed with a language code.

You can debug this using the command line tool:

php bin/console router:match "/"

If it's successful it should return something like this:

 [OK] Route "homepage" matches


+--------------+-------------------------------------------------------------------------------------------+
| Property     | Value                                                                                     |
+--------------+-------------------------------------------------------------------------------------------+
| Route Name   | homepage                                                                                  |
| Path         | /                                                                                         |
| Path Regex   | #^/$#sD                                                                                   |
| Host         | ANY                                                                                       |
| Host Regex   |                                                                                           |
| Scheme       | ANY                                                                                       |
| Method       | GET                                                                                       |
| Requirements | NO CUSTOM                                                                                 |
| Class        | Symfony\Component\Routing\Route                                                           |
| Defaults     | _controller: App\Controller\HomeController::index                                         |
| Options      | compiler_class: Symfony\Component\Routing\RouteCompiler                                   |
+--------------+-------------------------------------------------------------------------------------------+

If it is not successful there are multiple options. You could create a listener for the "/" route that tries to determine the proper locale and then redirects to the correct one or just always redirect to your "primary" language, eg using a route like this:

homepage:
    path: /
    controller: Symfony\Bundle\FrameworkBundle\Controller\RedirectController::urlRedirectAction
    defaults:
        path: /en
        permanent: true

edit for clarification:

Your routes/annotation.yaml could then look like this:

controllers:
    resource: ../../src/Controller/
    type: annotation
    prefix:
        fr: '/fr'
        en: '/en'
        de: '/de'

home_fallback:
    path: /
    controller: Symfony\Bundle\FrameworkBundle\Controller\RedirectController::urlRedirectAction
    defaults:
        path: /en
        permanent: true