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04.

The HTTP Client Service

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We don't have a database yet... and we'll save that for a future tutorial. But to make things a bit more fun, I've created a GitHub repository - https://github.com/SymfonyCasts/vinyl-mixes - with a mixes.json file that holds a fake database of vinyl mixes. Let's make an HTTP request from our Symfony app to this file and use that as our temporary database.

So... how can we make HTTP requests in Symfony? Well, making an HTTP request is work, and - say it with me now - "Work is done by a service". So the next question is: Is there already a service in our app that can make HTTP requests?

Let's find out! Spin over to your terminal and run:

php bin/console debug:autowiring http

to search the services for "http". We do get a bunch of results, but... nothing that looks like an HTTP client. And, that's correct. There is not currently any service in our app that can make HTTP requests.

Installing the HTTPClient Component

But, we can install another package to give us one. At your terminal, type:

composer require symfony/http-client

But, before we run that, I want to show you where this command comes from. Search for "symfony http client". One of the top results is Symfony.com's documentation that teaches about an HTTP Client component. Remember: Symfony is a collection of many different libraries, called components. And this one helps us make HTTP requests!

Near the top, you'll see a section called "Installation", and there's the line from our terminal!

Anyways, if we run that... cool! Once it finishes, try that debug:autowiring command again:

php bin/console debug:autowiring http

And... here it is! Right at the bottom: HttpClientInterface, which

Provides flexible methods for requesting HTTP resources synchronously or asynchronously.

The Super Smart FrameworkBundle

Woo! We just got a new service! That means that we must have just installed a new bundle, right? Because... bundles give us services? Well... go check out config/bundles.php:

14 lines | config/bundles.php
<?php
return [
Symfony\Bundle\FrameworkBundle\FrameworkBundle::class => ['all' => true],
Symfony\Bundle\TwigBundle\TwigBundle::class => ['all' => true],
Twig\Extra\TwigExtraBundle\TwigExtraBundle::class => ['all' => true],
Symfony\Bundle\WebProfilerBundle\WebProfilerBundle::class => ['dev' => true, 'test' => true],
Symfony\Bundle\MonologBundle\MonologBundle::class => ['all' => true],
Symfony\Bundle\DebugBundle\DebugBundle::class => ['dev' => true],
Symfony\WebpackEncoreBundle\WebpackEncoreBundle::class => ['all' => true],
Symfony\UX\Turbo\TurboBundle::class => ['all' => true],
Knp\Bundle\TimeBundle\KnpTimeBundle::class => ['all' => true],
];

Woh! There's no new bundle here! Try running

git status

Yea... that only installed a normal PHP package. Inside composer.json, here's the new package... But it's just a "library": not a bundle.

86 lines | composer.json
{
// ... lines 2 - 5
"require": {
// ... lines 7 - 15
"symfony/http-client": "6.1.*",
// ... lines 17 - 24
},
// ... lines 26 - 84
}

So, normally, if you install "just" a PHP library, it gives you PHP classes, but it doesn't hook into Symfony to give you new services. What we just saw is a special trick that many of the Symfony components use. The main bundle in our app is framework-bundle. In fact, when we started our project, this was the only bundle we had. framework-bundle is smart. When you install a new Symfony component - like the HTTP Client component - that bundle notices the new library and automatically adds the services for it.

So the new service comes from framework-bundle... which adds that as soon as it detects that the http-client package is installed.

Using the HttpClientInterface service

Anyways, time to use the new service. The type we need is HttpClientInterface. Head over to VinylController.php and, up here in the browse() action, autowire HttpClientInterface and let's name it $httpClient:

69 lines | src/Controller/VinylController.php
// ... lines 1 - 7
use Symfony\Contracts\HttpClient\HttpClientInterface;
// ... lines 9 - 10
class VinylController extends AbstractController
{
// ... lines 13 - 31
public function browse(HttpClientInterface $httpClient, string $slug = null): Response
{
// ... lines 34 - 41
}
// ... lines 43 - 67
}

Then, instead of calling $this->getMixes(), say $response = $httpClient->. This lists all of its methods... we probably want request(). Pass this GET... and then I'll paste the URL: you can copy this from the code block on this page. It's a direct link to the content of the mixes.json file:

69 lines | src/Controller/VinylController.php
// ... lines 1 - 10
class VinylController extends AbstractController
{
// ... lines 13 - 31
public function browse(HttpClientInterface $httpClient, string $slug = null): Response
{
// ... line 34
$response = $httpClient->request('GET', 'https://raw.githubusercontent.com/SymfonyCasts/vinyl-mixes/main/mixes.json');
// ... lines 36 - 41
}
// ... lines 43 - 67
}

Cool! So we make the request and it returns a response containing the mixes.json data that we see here. Fortunately, this data has all of the same keys as the old data we were using down here... so we should be able to swap it in super easily. To get the mix data from the response, we can say $mixes = $response->toArray():

69 lines | src/Controller/VinylController.php
// ... lines 1 - 10
class VinylController extends AbstractController
{
// ... lines 13 - 31
public function browse(HttpClientInterface $httpClient, string $slug = null): Response
{
// ... line 34
$response = $httpClient->request('GET', 'https://raw.githubusercontent.com/SymfonyCasts/vinyl-mixes/main/mixes.json');
$mixes = $response->toArray();
// ... lines 37 - 41
}
// ... lines 43 - 67
}

a handy method that JSON decodes the data for us!

Moment of truth! Move over, refresh and... it works! We now have six mixes on the page. And... super cool! A new icon showed up on the web debug toolbar: "Total requests: 1". The HTTP Client service hooks into the web debug toolbar to add this, which is pretty awesome. If we click it, we can see info about the request and the response. I love that.

To celebrate this working, spin back over and remove the hardcoded getMixes() method:

44 lines | src/Controller/VinylController.php
// ... lines 1 - 10
class VinylController extends AbstractController
{
// ... line 13
public function homepage(): Response
{
// ... lines 16 - 28
}
// ... lines 30 - 31
public function browse(HttpClientInterface $httpClient, string $slug = null): Response
{
// ... lines 34 - 41
}
}

The only problem I can think of now is that, every single time someone visits our page, we're making an HTTP request to GitHub's API... and HTTP requests are slow! To make matters worse, once our site becomes super popular - which won't take long - GitHub's API will probably start rate limiting us.

To fix this, let's leverage another Symfony service: the cache service.