C++ Boost http post request [duplicate] - c++

Question

I've to use a C++ library for sending data to a REST-Webservice of our company.
I start with Boost and Beast and with the example given here under Code::Blocks in a Ubuntu 16.04 enviroment.
The documentation doesn't helped me in following problem:
My code is, more or less, equal to the example and I can compile and send a GET-request to my test webservice successfully.
But how can I set data inside the request (req) from this definition:
:
beast::http::request<beast::http::string_body> req;
req.method("GET");
req.target("/");
:
I tried to use some req.body.???, but code completition doesn't give me a hint about functionality (btw. don't work). I know that req.method must be changed to "POST" to send data.
Google doesn't show new example about this, only the above code is found as a example.
Someone with a hint to a code example or using about the Beast (roar). Or should I use websockets? Or only boost::asio like answered here?
Thanks in advance and excuse my bad english.

Answer 1

Small addition to Eliott Paris's answer:
Correct syntax for setting body is
req.body() = "name=foo";
You should add
req.prepare_payload();
after setting the body to set body size in HTTP headers.

Answer 2

To send data with your request you'll need to fill the body and specify the content type.
beast::http::request<beast::http::string_body> req;
req.method(beast::http::verb::post);
req.target("/");
If you want to send "key=value" as a "x-www-form-urlencoded" pair:
req.set(beast::http::field::content_type, "application/x-www-form-urlencoded");
req.body() = "name=foo";
Or raw data:
req.set(beast::http::field::content_type, "text/plain");
req.body() = "Some raw data";