default_locale not passed to UrlGenerator

[HypeMC]

Symfony version(s) affected: >=4.1

Description
Symfony 4.1 introduced Internationalized routing.
After defining a route with multiple locale I tried to generate a url with a command and got the following error:

Unable to generate a URL for the named route "locale" as such route does not exist.

The route:

    /**
     * @Route({
     *    "en": "/locale",
     *    "hr": "/lokalno"
     * }, name="locale")
     */

The code that generates the url:

$this->router->generate('locale');

After some playing around I realized that I need to explicitly set the locale in order for the url to be generated, which was strange since I had the framework.default_locale set to hr.

// This works
$this->router->generate('locale.hr');

I did a little digging and noticed that the UrlGenerator class has a $defaultLocale parameter and the following code:

$locale = $parameters['_locale']
    ?? $this->context->getParameter('_locale')
    ?: $this->defaultLocale;

The problem is that the $defaultLocale parameter is never set when the class is instantiated. I would expect the framework.default_locale parameter to be passed here.

How to reproduce

# framework.yaml
framework:
    default_locale: hr

// Controller
class LocaleController extends AbstractController
{
    /**
     * @Route({
     *    "en": "/locale",
     *    "hr": "/lokalno"
     * }, name="locale")
     */
    public function index()
    {
        // ...
    }
}

// Command
class LocaleCommand extends Command
{
    protected static $defaultName = 'app:locale';

    // ...

    protected function execute(InputInterface $input, OutputInterface $output)
    {
        $output->writeln($this->router->generate('locale'));
    }
}

Possible Solution

A possible solution would be to override the way the UrlGenerator class is instantiated in the FrameworkBundle Router class and pass the framework.default_locale as the $defaultLocale parameter.

[fancyweb]

IIRC, it is possible to have an i18n route "my_route" (so its names are technically my_route.en, my_route.hr, etc.) and an unrelated route with the name "my_route".

Passing the default locale to the UrlGenerator would be a BC break because it would generate another route than currently with the default value.

I think we need to deprecate having a route with the same name than an i18n route so we can actually do something about this in Symfony 5.0.

Kind of related to : #30010

[HypeMC]

Not sure it would be a BC break since the problem is that there's inconsistent behavior between the web and cli contexts. The route exists when generated in a web request cause it gets the locale from the request context ($this->context->getParameter('_locale')):

class LocaleController extends AbstractController
{
    /**
     * @Route({
     *    "en": "/locale",
     *    "hr": "/lokalno"
     * }, name="locale")
     */
    public function index()
    {
        // This works
        return new Response($this->generateUrl('locale'));
    }
}

[X-Coder264]

Currently the same route generation call behaves differently depending on the context it's being run in (WEB or CLI). In a WEB context the above route would be generated just fine, while in CLI it'd throw an exception. The system does not behave consistently and I don't see how this can be treated as anything but a bug.

Another solution which would avoid this "breaking change" and allow us to make the behavior consistent no matter the context is adding another parameter (let's call it router.request_context.defaut_locale for example) which would work the same as all other similar parameters as described in https://symfony.com/doc/current/console/request_context.html

Since that parameter doesn't exist yet it would always default to null unless explicitly set so the current behavior remains the same while it allows developers to override/customize it.

[stof]

Adding this new parameter looks good to me.

[HypeMC]

@stof Hm, but would we then have two different parameters/configuration options for the same thing, framework.default_locale & router.request_context.defaut_locale?

[stof]

We don't have framework.default_locale. We have framework.translator.default_locale, which will not exist at all if you don't enable the translator. So we cannot make it a hard dependency.

[HypeMC]

@stof Not sure what you mean, I was referring to the FrameworkBundle configuration, which is set as kernel.default_locale.

The default locale is used if no _locale routing parameter has been set.

[stof]

hmm indeed. I confused things. Using the kernel.default_locale would indeed make sense then.