[Routing] Allow using services in the route condition

[renanbr]

Q	A
Branch?	6.1
Bug fix?	no
New feature?	yes
Deprecations?	no
Tickets	n/a
License	MIT
Doc PR	n/a

#[AsRoutingConditionService(alias: 'foo')]
class SomeFooService
{
    public function bar(): bool { ... }
}

class DefaultController
{
    #[Route('/page', condition: "service('foo').bar()")]
    public function page(): Response { ... }
} 

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[nicolas-grekas]

On second though, we might want to go a bit further: with the current approach, referenced services are going to be instantiated all the time, while they might be needed only on very specific routes.
What about providing a service locator instead, after making EL able to deal with them?

[chapterjason]

What if two services are registered with the same name? This could cause some confusing issues, every service will override the one registered before.

If docs will be added: prefix the service names in third party bundles.

[renanbr]

@nicolas-grekas

On second though, we might want to go a bit further: with the current approach, referenced services are going to be instantiated all the time, while they might be needed only on very specific routes.
What about providing a service locator instead, after making EL able to deal with them?

Instantiating services all the time is indeed not good. Based on your feedback I was wondering if we could inject a function that relies on a service locator instead of injecting variables

#[Route('/page', condition: "service('myService').myMethod()")]

Pros:

• No changes in UrlMatcher (we can use the already available function provider feature)
• We'll create services only when requested

What do you think?

[nicolas-grekas]

I like it @renanbr!

[renanbr]

Status: Since eafc9c5, the FrameworkBundle wraps tagged services into a ServiceLocator, then passes it to the routing component, which unpacks services in the matcher when necessary.

I'm satisfied with this ☝🏼 solution.

My next shot will be implementing service('name') as described in #44405 (comment)

[jvasseur]

Why not using the ExpressionFunctionProviderInterface extension point instead of creating a new way of extending the expression language ?

[nicolas-grekas]

Why not using the ExpressionFunctionProviderInterface extension point instead of creating a new way of extending the expression language ?

For convenience I think. What would be the DX of your proposal?

[nicolas-grekas]

@renanbr up to finish this PR?

[GromNaN]

Why not using the ExpressionFunctionProviderInterface extension point instead of creating a new way of extending the expression language ?

For convenience I think. What would be the DX of your proposal?

Late it the discussion. A new function service() would provide access to the container.

class DefaultController
{
    #[Route('/page', condition: 'service('foo').bar()')]
    public function page(): Response { ... }
} 

[nicolas-grekas]

A new function service() would provide access to the container.

The one true container you mean? I guess that's no-go since that'd require services to be made public. The benefit of this proposal is that it allows labeling which services need to be made available for the routing layer.

[GromNaN]

Maybe a service locator, feed with regular tagged services.

[nicolas-grekas]

That's exactly what this PR does IIUC :)

[GromNaN]

Indeed. Then the description needs to be updated.

[renanbr]

@renanbr up to finish this PR?

I'll work on this week and the next week.

thanks for the review btw

[nicolas-grekas]

This is so rad! Please add a few tests and we'll be good!

[renanbr]

updated,
latest changes

• rename tag to routing.condition_service;
• rename tag identifier to alias;
• rename class attribute to AsRoutingConditionService;
• move class attribute under FrameworkBundle;
• rename expression language function to container.get_routing_condition_service;
• add tests

[Tobion]

Well done

[Tobion]

Thanks @renanbr for working on this feature, this is much appreciated.