More about Services
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Login SubscribeWe already know that services come from bundles. And every service is a combination of an ID, a class, and a set of arguments that are needed to instantiate it. But, did you know that we can also create our own services to organize our code for better maintainability? Yep! Believe it or not, we already created one in the previous episode.
Open up StarshipRepository.php. We created this without configuration and we're still able to use it in StarshipApiController.php. But how can we do that? This works thanks to config/services.yaml. Let's open that. Down here, below our services key, we see this App\ section. This code registers everything in our src/ directory as a service. But it also excludes some things, like DependencyInjection, Entity, and Kernel.php.
| // ... lines 1 - 7 | |
| services: | |
| // ... lines 9 - 15 | |
| App\: | |
| resource: '../src/' | |
| exclude: | |
| - '../src/DependencyInjection/' | |
| - '../src/Entity/' | |
| - '../src/Kernel.php' | |
| // ... lines 22 - 25 |
This services.yaml file, including this config, comes with the core symfony/framework-bundle.
Up here, we have this _defaults key.
| // ... lines 1 - 7 | |
| services: | |
| // ... line 9 | |
| _defaults: | |
| autowire: true # Automatically injects dependencies in your services. | |
| autoconfigure: true # Automatically registers your services as commands, event subscribers, etc. | |
| // ... lines 13 - 25 |
That's the configuration for all of the services in this file. This autowire key, set to true, automaticallyinjects dependencies into our services. We also have this autoconfigure key, set to true, which automatically registers our services as commands, event subscribers, etc. Pretty cool! We will talk more about autoconfigure later.
To see a list of services, at your terminal, run:
bin/console debug:autowiring
But this time, let's add the --all option at the end:
bin/console debug:autowiring --all
This will show us all of our services - even the ones that aren't aliased. Technically non-services like our Model class are registered as services too, but they're removed later because we're not using them in our code. The point is, to create a service, all we need to do is create a class somewhere in our src/ directory and autowiring is automatically enabled for it.
By the way, all these .yaml files are identical. The root key, like services or framework, is what makes them different. This means you could copy all of the config from every file into a single .yaml file and it would work the same way. We just keep them separated for maintainability, andour sanity.
Next: You've heard me say over and over that the container holds services, and that's true. But it also holds one other thing - a simple configuration called parameters.
