Symfony version(s) affected

All

Description

The current implementation or UrlGenerator works if you have a path specified for every locale.

For example if you have a route like this:

    #[Route(
        path: [
            'en' => '/{_locale}/test-route',
            'de' => '/{_locale}/test-route',
        ],
        name: 'test_route',
        requirements: ['_locale' => 'en|de|...'],
    )]

Internally it creates two routes:

test_route.en
test_route.de

and everything works as expected since before generating a route the UrlGenerator uses the fallback locale if one is not specified and finds the correct route.

The problem is if you for example have a lot of languages and do not want to localize the path for every language and you have routes defined like this:

    #[Route(
        path: '/{_locale}/test-route',
        name: 'test_route',
        requirements: ['_locale' => 'en|de|...'],
    )]

In this case test_route.en does not exist and the generator tries to generate a route and fails if the _locale part is missing.

For handling code that is part of a web request this still works since _locale is set in the RequestContext by Symfony\Component\HttpKernel\EventListener::onKernelRequest(), unfortunately this is not executed for code that is running as a console application or when performing tests by booting the Kernel and fetching a service from it.

How to reproduce

Create a route like this:

    #[Route(
        path: '/{_locale}/test-route',
        name: 'test_route',
        requirements: ['_locale' => 'en|de'],
    )]

Inject an UrlGeneratorInterface into a Console application and try to generate a link with $router->generate('test_route') and you will get an Exception:

[Symfony\Component\Routing\Exception\MissingMandatoryParametersException]
  Some mandatory parameters are missing ("_locale") to generate a URL for route "test_route".

Possible Solution

It would be nice if setting default_locale would work consistently or at least allow us to set the default parameters for the context the same way we can set router.request_context.host or router.request_context.scheme (I've tried settings router.request_context.parameters but for some reason it didn't work and I didn't investigate further).

Additional Context

No response