I have recently had to implement Guzzle for the first time and it is a fairly simple library to use.
First I created a new Client
// Passed in our options with just our base_uri in
$client = new Client(["base_uri" => "http://example.com"]);
I then created a POST request, not how I am using new Request instead of $client->request(... though. This doesn't really matter to much that I've used new Request though.
// Create a simple request object of type 'POST' with our remaining URI
// our headers and the body of our request.
$request = new Request('POST', '/api/v1/user/', $this->_headers, $this->body);
so in essence it would look like:
$request = new Request('POST', '/api/v1/user/', ['Content-Type' => "application/json, 'Accept' => "application/json], '{"username": "myuser"}');
$this->headers is a simple key-value pair array of our request headers making sure to set the Content-Type header and $this->body is a simple string object, in my case it forms a JSON body.
I can simply then just call the $client->send(... method to send the request like:
// send would return us our ResponseInterface object as long as an exception wasn't thrown.
$rawResponse = $client->send($request, $this->_options);
$this->_options is a simple key-value pair array again simple to the headers array but this includes things like timeout for the request.
For me I have created a simple Factory object called HttpClient that constructs the whole Guzzle request for me this is why I just create a new Request object instead of calling $client->request(... which will also send the request.