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Non-Autowireable Arguments


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Earlier, we learned that we can fetch parameters from the container with getParameter() in our controller. We also saw how easy it is to create our own services. And guess what? That's not the only thing we can customize! We can also create our own parameters. How? I'll show you!

Open config/services.yaml. Here, we see an empty parameters section. Inside, let's create a new parameter - how about iss_location_cache_ttl - and let's set it to 5.

26 lines | config/services.yaml
// ... lines 1 - 5
iss_location_cache_ttl: 5
// ... lines 8 - 26

We'll use this parameter in the configuration to avoid hard coding anything. But first, head back to MainController.php, and instead of dumping kernel.project_dir, let's dump our new parameter: iss_location_cache_ttl.

39 lines | src/Controller/MainController.php
// ... lines 1 - 13
class MainController extends AbstractController
// ... line 16
public function homepage(
// ... lines 18 - 20
): Response {
// ... lines 23 - 36

Over in our browser, refresh and... there it is - 5!

Now, we know we can grab this with getParameter() in our controllers. But what do we do if we're not in a controller? How can we use parameters in services without this fancy getParameter() method? Let's see... If we add a new argument to the homepage - $issLocationCacheTtl - and dump this instead of getParameter(), when we refresh... error!

40 lines | src/Controller/MainController.php
// ... lines 1 - 16
public function homepage(
// ... lines 18 - 20
): Response {
// ... lines 23 - 37
// ... lines 39 - 40

Symfony can't autowire that argument. It can autowire services, but this isn't a service; It's a parameter. So how do we do this? The answer: Autowire it! We can autowire parameters just like services, and it will work in the constructor or controller just like normal autowiring. Check it out!

Back in our code, let's add the autowire attribute above the argument. Write #[Autowire()] and, inside, param: 'iss_location_cache_ttl'.

42 lines | src/Controller/MainController.php
// ... lines 1 - 6
use Symfony\Component\DependencyInjection\Attribute\Autowire;
// ... lines 8 - 14
class MainController extends AbstractController
// ... line 17
public function homepage(
// ... lines 19 - 21
#[Autowire(param: 'iss_location_cache_ttl')]
): Response {
// ... lines 25 - 39

Back at our browser, if we refresh the page... 5! It works! Okay, let's remove that and see how we can use our new parameter in our config.

Open config/packages/cache.yaml. Instead of this hard-coded value, say %iss_location_cache_ttl%.

28 lines | config/packages/cache.yaml
// ... lines 3 - 19
default_lifetime: '%iss_location_cache_ttl%'
// ... lines 23 - 28

If we check this in our browser... everything still works! Awesome!

Before we continue, I want to show you one more way you can autowire parameters: parameter binding. Open services.yaml and, in services, below _defaults, add a new section: bind. Inside, add our variable name - $issLocationCacheTtl - set to %iss_location_cache_ttl%.

As soon as we match the argument with the name we wrote in bind, Symfony will automatically autowire it to this parameter. We can also add a type-hint - int - in case we want to autowire $issLocationCacheTtl with a required type-hint. In MainController.php, we need to add int here as well.

When we try it... this works too! And since we're autowiring globally, we avoid duplicating our autowired PHP attributes in multiple places. Super handy! Since we're not currently using that parameter anywhere except our config, we can get rid of this for now.

Next: Let's see how we can autowire non-autowireable services. It's surprisingly easy.