Autowiring & Service Deprecations

Woo! There are only two deprecations left on the homepage... but they're weird! And actually, they're not real! These are false deprecation warnings!

Upgrade to the Symfony 3.3 services.yml Config!

In our Symfony 3.3 Tutorial, we talked a lot about all the new service autowiring & auto-registration stuff. We also upgraded our old services.yml file to use the new fancy config. It turns out that doing this is one of the biggest steps in upgrading to Symfony 4 and Flex. If you have not already upgraded your services.yml file to use autowiring & service auto-registration, stop and go through the Symfony 3.3 tutorial now.

Strict Autowiring Mode

The way that autowiring works changed in Symfony 4. In Symfony 3, when Symfony saw a type-hint - like EntityManager - it would first look to see if there was a service or alias in the container with that exact id: so Doctrine\ORM\EntityManager. If there was not, it would then scan every service looking to see if any were an instance of this class. That magic is gone.

In Symfony 4, it's simpler: autowiring only does the first part: if there is not a service whose id is Doctrine\ORM\EntityManager, it throws an exception. This is a great change: the system is simpler and more predictable.

So, of course, if any of your autowiring depends on the old, deprecated logic, you'll see a deprecation message. And yea, that's where these messages are coming from!

But, there's a better way to find this deprecated logic. Open app/config/config.yml. Under parameters, add container.autowiring.strict_mode: true.

This tells Symfony to use the simpler, Symfony 4-style autowiring logic right now. Instead of deprecations, you'll see great big, beautiful errors when you try to refresh.

So... try it! Refresh the homepage. Woh! No errors! That's because we already fixed all our old autowiring logic in the Symfony 3.3 tutorial. And... the 2 deprecation messages are gone! Those were not real issues: it's a rare situation where the deprecation system is misreporting.

Services are now Private

So yes! This means that... drumroll... our homepage is ready for Symfony 4.0! But the rest of the site might not be. Surf around to see what other deprecations we can find. The login page looks ok: login with weaverryan+1@gmail.com, password iliketurtles. Go to /genus... still no issues and then... ah! Finally, 1 deprecation on the genus show page.

Check it out. Interesting:

The "logger" service is private, getting it from the container is deprecated since Symfony 3.2. You should either make this service public or stop using the container directly.

Wow! This is coming from GenusController line 84. Go find it! Close a few files, then open this one. Scroll down to 84. Ah!

This is really important. Open services.yml. These days, all of our services are private by default: public: false. This allows Symfony to optimize the container and all it really means is that we cannot fetch these services directly from the container. So $container->get() will not work.

In Symfony 4, this is even more important because a lot of previously public services, like logger, are now private. Here's the point: you need to stop fetching services directly form the container... everywhere. It's just not needed anymore.

Fixing $container->get()

What's the solution? Since we're in a controller, add a LoggerInterface $logger argument. Then, just $logger->info().

Isn't that better anyways? As soon as we refresh the page... deprecation gone!

Where else are we using $container->get()? Let's find out! In your terminal, run:

git grep '\->get('

Ah, just two more! We may not need to change all of these... some services are still public. But let's clean it all up!

Start in SecurityController. Ah, here it is. So: what type-hint should we use to replace this? Well, you could just guess! Honestly, that works a lot. Or try the brand new console command:

./bin/console debug:autowiring

Sweet! This is a full list of all type-hints you can use for autowiring. Search for "authentication" and... there it is! This type-hint is an alias to the service we want.

That means, back in SecurityController, delete this line and add a new AuthenticationUtils $authenticationUtils argument. Done.

The last spot is in UserController: we're using security.authentication.guard_handler. This time, let's guess the type-hint! Add a new argument: Guard... GuardAuthenticationHandler. That's probably it! And if we're wrong, Symfony will tell us. Use that value below.

And yep, you can see the GuardAuthenticationHandler class in the debug:autowiring list. But... what if it weren't there? What if we were trying to autowire a service that was not in this list?

Well... you would get a huge error. And maybe you should ask yourself: is this not a service I'm supposed to be using?

But anyways, if it's not in the list, there's a simple solution: go to services.yml and add your own alias. At the bottom, paste the class you want to use as the type-hint, then copy the service id, and say @ and paste.

Yep, that is all you need to do in order to define your own autowiring rules. Since we don't need it in this case, comment it out.

Ok, refresh! At this point, our goal is to hunt for deprecations until we're pretty confident they're gone: it's not an exact science. If you have a test suite, you can use the symfony/phpunit-bridge to get a report of deprecated code paths that are hit in your tests.

Adding $form->isSubmitted()

There is one more deprecation on the registration page. Look at the details:

Call Form::isValid() on an unsubmitted form is deprecated. Use Form::isSubmitted() before Form::isValid().

This comes from UserController. Open that class and search for isValid(). Before $form->isValid(), add $form->isSubmitted(). Find again and fix the other spot. This isn't very important... you just need both in Symfony 4.

And now... I think we're done! All the deprecations I could find are gone.

It's time to upgrade to Symfony 4. Which, by the way, is the fastest Symfony version ever! Zoom!