Is it possible to send POST requests with Guzzle and how?

Yes, it is possible to send POST requests using Guzzle, a PHP HTTP client that makes it easy to send HTTP requests and trivial to integrate with web services.

Here's an example of how you can send a POST request with Guzzle:

First, make sure you have Guzzle installed. If you haven't installed it yet, you can use Composer to install it with the following command:

composer require guzzlehttp/guzzle

Once you have Guzzle installed, you can send a POST request as follows:

<?php
require 'vendor/autoload.php';

use GuzzleHttp\Client;
use GuzzleHttp\Exception\RequestException;

$client = new Client();

try {
    $response = $client->post('http://httpbin.org/post', [
        'form_params' => [
            'field1' => 'value1',
            'field2' => 'value2',
        ]
    ]);

    // Get the body of the response
    $body = $response->getBody();
    $content = $body->getContents();

    echo $content; // Outputs the JSON returned by the POST request
} catch (RequestException $e) {
    // Handle the exception or get the response if available
    if ($e->hasResponse()) {
        $response = $e->getResponse();
        echo $response->getBody()->getContents();
    } else {
        echo $e->getMessage();
    }
}

In the above example, we are making a POST request to http://httpbin.org/post, which is a simple HTTP request and response service. We're sending form parameters field1 and field2 with the values value1 and value2, respectively.

The form_params option is used to send an application/x-www-form-urlencoded POST request, which is the type of request commonly used for submitting web forms.

Guzzle will throw exceptions for errors that occur during a request (4xx and 5xx responses). You can catch these exceptions using a try-catch block and handle them accordingly. The RequestException provides a hasResponse() method that can be used to determine if a server response is available.

For JSON requests, you can use the json option instead of form_params:

$response = $client->post('http://httpbin.org/post', [
    'json' => [
        'field1' => 'value1',
        'field2' => 'value2',
    ]
]);

This will send the request with a Content-Type header of application/json and the body of the request will be a JSON-encoded string.