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10.

Creating your own Service

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We know that services do work, and we know that Symfony is full of services that we can use. If you run:

php bin/console debug:autowiring

We get the dinner menu of services, where you can order any of these by adding an argument type-hinted with the matching class or interface.

We, of course, also do work in our code... hopefully. Right now, all that work is being done inside our controller, like creating the Starship data. Sure, this is hard-coded right now, but imagine if this were real work: like a complex database query. Putting the logic inside a controller is "ok"... but what if we wanted to reuse this code somewhere else? What if, on our homepage, we wanted to get a dynamic count of the Starships by grabbing this same data?

Creating the Service Class

To do that, we need to move this "work" into its own service that both controllers could then use. In the src/ directory, create a new Repository directory and a new PHP class inside called StarshipRepository.

8 lines | src/Repository/StarshipRepository.php
// ... lines 1 - 2
namespace App\Repository;
class StarshipRepository
{
}

Just like when we built our Starship class, this new class has absolutely nothing to do with Symfony. It's just a class that we've decided to create to organize our work. And so, Symfony doesn't care what it's called, where it lives or what it looks like. I called it StarshipRepository and put it in a Repository directory because that's a common programming name for a class whose "work" is to fetch a type of data, like Starship data.

Autowiring the New Service

Ok, before we even do anything in here, let's see if we can use this inside a controller. And, good news! Just by creating this class, it's already available for autowiring. Add a StarshipRepository $repository argument, and, to make sure it's working, dd($repository).

46 lines | src/Controller/StarshipApiController.php
// ... lines 1 - 5
use App\Repository\StarshipRepository;
// ... lines 7 - 11
class StarshipApiController extends AbstractController
{
// ... line 14
public function getCollection(LoggerInterface $logger, StarshipRepository $repository): Response
{
$logger->info('Starship collection retrieved');
dd($repository);
// ... lines 19 - 43
}
}

All right, spin over, click back to our endpoint, and... got it. That's so cool! Symfony saw the StarshipRepository type-hint, instantiated that object, then passed it to us. Delete the dd()... and let's move the starship data inside. Copy it... and create a new public function called, how about, findAll(). Inside, return, then paste.

36 lines | src/Repository/StarshipRepository.php
// ... lines 1 - 4
use App\Model\Starship;
class StarshipRepository
{
public function findAll(): array
{
return [
new Starship(
1,
'USS LeafyCruiser (NCC-0001)',
'Garden',
'Jean-Luc Pickles',
'taken over by Q'
),
new Starship(
2,
'USS Espresso (NCC-1234-C)',
'Latte',
'James T. Quick!',
'repaired',
),
new Starship(
3,
'USS Wanderlust (NCC-2024-W)',
'Delta Tourist',
'Kathryn Journeyway',
'under construction',
),
];
}
}

Back over in StarshipApiController, delete that... and it's beautifully simple: $starships = $repository->findAll().

22 lines | src/Controller/StarshipApiController.php
// ... lines 1 - 4
use App\Repository\StarshipRepository;
// ... lines 6 - 10
class StarshipApiController extends AbstractController
{
#[Route('/api/starships')]
public function getCollection(LoggerInterface $logger, StarshipRepository $repository): Response
{
$logger->info('Starship collection retrieved');
$starships = $repository->findAll();
// ... lines 18 - 19
}
}

Done! When we try it, it still works... and now the code for fetching starships is nicely organized into its own class and reusable across our app.

Constructor Autowiring

With that victory under our belt, let's doing something harder. What if, from inside StarshipRepository, we needed access to another service to help us do our work? No problem! We can use autowiring! Let's try to autowire the logger service again.

The only difference this time is that we're not going to add the argument to findAll(). I'll explain why in a minute. Instead, add a new public function __construct() and do the auto-wiring there: private LoggerInterface $logger.

43 lines | src/Repository/StarshipRepository.php
// ... lines 1 - 5
use Psr\Log\LoggerInterface;
class StarshipRepository
{
public function __construct(private LoggerInterface $logger)
{
}
// ... lines 13 - 41
}

Down below, to use it, copy the code from our controller, delete that, paste it here, and update it to $this->logger.

43 lines | src/Repository/StarshipRepository.php
// ... lines 1 - 5
use Psr\Log\LoggerInterface;
class StarshipRepository
{
public function __construct(private LoggerInterface $logger)
{
}
public function findAll(): array
{
$this->logger->info('Starship collection retrieved');
// ... lines 17 - 40
}
}

Cool! Over in the controller, we can remove that argument because we're not using it anymore.

Testing time! Refresh! No error - that's a good sign. To see if it logged something, go to /_profiler, click on the top request, Logs, and... there it is!

So let me explain why we added the service argument to the constructor. If we want to fetch a service - like the logger, a database connection, whatever, this is the correct way to use autowiring: add a __construct method inside another service. The trick we saw earlier - where we add the argument to a normal method - yeah, that's special and only works for controller methods. It's an extra convenience that was added to the system. It's a great feature, but the constructor way... that's how autowiring really works.

And this "normal" way, it even works in a controller. You could add a __construct() method with an autowirable argument and that would totally work.

The point is: if you are in a controller method, sure, add the argument to the method - it's nice! Just remember that it's a special thing that only works here. Everywhere else, autowire through the constructor.

Using the Service on another Page

Let's celebrate our new service by using it on the homepage. Open up MainController. This hardcoded $starshipCount is so 30 minutes ago. Autowire StarshipRepository $starshipRepository, then say $ships = $starshipRepository->findAll() and count them with count().

25 lines | src/Controller/MainController.php
// ... lines 1 - 4
use App\Repository\StarshipRepository;
// ... lines 6 - 9
class MainController extends AbstractController
{
#[Route('/')]
public function homepage(StarshipRepository $starshipRepository): Response
{
$ships = $starshipRepository->findAll();
$starshipCount = count($ships);
// ... lines 17 - 22
}
}

While we're here, instead of this hardcoded $myShip array, let's grab a random Starship object. We can do that by saying $myShip equals $ships[array_rand($ships)]

25 lines | src/Controller/MainController.php
// ... lines 1 - 4
use App\Repository\StarshipRepository;
// ... lines 6 - 9
class MainController extends AbstractController
{
#[Route('/')]
public function homepage(StarshipRepository $starshipRepository): Response
{
$ships = $starshipRepository->findAll();
$starshipCount = count($ships);
$myShip = $ships[array_rand($ships)];
// ... lines 18 - 22
}
}

Let's try it! Hunt down your browser and head to the homepage. Got it! We see the randomly changing ship down here, and the correct ship number up here... because we're multiplying it by 10 in the template.

Printing Objects in Twig

And something crazy-cool just happened! A minute ago, myShip was an associative array. But we changed it to be a Starship object. And yet, the code on our page kept working. We just accidentally saw a superpower of Twig. Head to templates/main/homepage.html.twig and scroll down to the bottom. When you say myShip.name, Twig is really smart. If myShip is an associative array, it'll grab the name key. If myShip is an object, like it is now, it will grab the name property. But even more than that, if you look at Starship, the name property is private, so we can't access it directly. Twig realizes that. It looks at the name property, sees that it's private, but also sees that there's a public getName(). And so, it calls that.

All we need to say is myShip.name... and Twig handles the details of how to fetch that, which I love.

Ok, one last tiny tweak. Instead of passing the starshipCount into our template, we can do the count inside Twig. Delete this variable, and instead, pass a ships variable.

24 lines | src/Controller/MainController.php
// ... lines 1 - 9
class MainController extends AbstractController
{
// ... line 12
public function homepage(StarshipRepository $starshipRepository): Response
{
$ships = $starshipRepository->findAll();
$myShip = $ships[array_rand($ships)];
// ... line 17
return $this->render('main/homepage.html.twig', [
'myShip' => $myShip,
'ships' => $ships,
]);
}
}

In the template, there we go, for the count, we can say ships, which is an array, and then use a Twig filter: |length.

44 lines | templates/main/homepage.html.twig
// ... lines 1 - 4
{% block body %}
// ... lines 6 - 9
<div>
Browse through {{ ships|length * 10 }} starships!
{% if ships|length > 2 %}
// ... lines 14 - 17
{% endif %}
</div>
// ... lines 20 - 42
{% endblock %}

That feels good. Let's do the same thing down here... and change it to greater than 2. Try that out. Our site just keeps working!

Next up: let's create more pages and learn how to make routes that are even smarter.