New in Symfony 4.3: HttpClient component
May 15, 2019 • Published by Javier Eguiluz
Warning: This post is about an unsupported Symfony version. Some of this information may be out of date. Read the most recent Symfony Docs.
Contributed by
Nicolas Grekas
in #30413.
Making HTTP requests (e.g. to third-party APIs) is a frequent need for developers working on web applications. In Symfony 4.3 we'll make this simpler with a brand new component called HttpClient.
Basic usage
The Symfony\Component\HttpClient\HttpClient
class provided to make HTTP
requests is quite straightforward:
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use Symfony\Component\HttpClient\HttpClient;
$httpClient = HttpClient::create();
$response = $httpClient->request('GET', 'https://api.github.com/repos/symfony/symfony-docs');
A significant difference with other existing HTTP clients is that the request()
call is not blocking. In other words, the $response
object is available
immediately and the code execution can continue.
Later, when you call to getStatusCode()
, the code execution will stop until
the headers are available and when you call to getContent()
, it will stop
until the full contents are available (but you can use Streaming responses):
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$statusCode = $response->getStatusCode();
// $statusCode = 200
$content = $response->getContent();
// returns the raw content returned by the server (JSON in this case)
// $content = '{"id":521583, "name":"symfony-docs", ...}'
$content = $response->toArray();
// transforms the response JSON content into a PHP array
// $content = ['id' => 521583, 'name' => 'symfony-docs', ...]
Thanks to this non-blocking behavior, you can make multiple calls to
request()
to perform parallel requests and then access the info of the
responses only after starting all requests.
By default, the component uses native PHP functions to make the HTTP requests, so you don't have to install any other dependency. However, it will use the cURL based transport if your system has both the cURL library and the PHP cURL extension installed.
When the HTTP status code of the response is not in the 200-299 range (i.e.
3xx
, 4xx
or 5xx
) your code is expected to handle it. If you don't do
that, the getHeaders()
and getContent()
methods throw an appropriate
exception:
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// the response of this request will be a 403 HTTP error
$response = $httpClient->request('GET', 'https://httpbin.org/status/403');
// this code results in a Symfony\Component\HttpClient\Exception\ClientException
// because it doesn't check the status code of the response
$content = $response->getContent();
// do this instead
if (200 !== $response->getStatusCode()) {
// handle the HTTP request error (e.g. retry the request)
} else {
$content = $response->getContent();
}
Features
The new HttpClient component is packed with useful features. All of them are explained in the docs:
- Support for HTTP Basic and HTTP Bearer authentications;
- Support for adding custom query string parameters and custom HTTP headers;
- Allow to upload data using strings, closures and PHP resources;
- Streaming responses to get chunks of the response sequentially instead of waiting for the entire response;
- Request and response caching;
- Scoping HTTP clients to auto-configure the client based on the requested URL;
- PSR-7 and PSR-18 Compatibility;
- MockHttpClient to simplify testing requests and responses.
Symfony framework integration
When using HttpClient inside a full Symfony application instead of as a
stand-alone component, you can configure it under the http_client
key
(check out the full HttpClient configuration reference):
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# config/packages/framework.yaml
framework:
# ...
http_client:
max_redirects: 7
max_host_connections: 10
Then, you can inject the HttpClient in other services as follows:
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use Symfony\Contracts\HttpClient\HttpClientInterface;
class SomeService
{
private $httpClient;
public function __construct(HttpClientInterface $httpClient)
{
$this->httpClient = $httpClient;
}
}
Future integrations
Having a default and official HTTP client for Symfony applications will allow us to implement other features that require communicating with third-party services. A recent example of this is the NotCompromisedPassword validator, which makes your applications more secure and uses the HttpClient component to make the HTTP requests required to check if a given password was publicly compromised or not.
In addition, the Mercure component is also switching their current HTTP client by the new HttpClient component (see PR #8). Finally, API Platform is going to introduce a new set of API testing utilities built with the HttpClient component (see PR #2608).
Help the Symfony project!
As with any Open-Source project, contributing code or documentation is the most common way to help, but we also have a wide range of sponsoring opportunities.
Comments are closed.
To ensure that comments stay relevant, they are closed for old posts.
What are the main differences with well known GuzzleHttp ?
Thanks
That's one of the reasons why the component itself does not implement the PSR-18 interface (we provide a bridge to PSR, but you will loose that benefit as the bridge will need to block on IO before returning the PSR-7 response).
Guzzle did have promise-based implementation for a long time, so it's not really that much different apart from the ability to stream the response in chunks in this regard.
Looking good though :)
https://speakerdeck.com/nicolasgrekas/symfony-httpclient-what-else