Sending HTTP POST requests using cpp-netlib

Question

UPDATED

I'm using cpp-netlib (v0.11.0) to send HTTP requests.

The following code sends an HTTP POST request with the given body.

client httpClient;

try
{
   uri::uri url;
   url << uri::scheme("http")
       << uri::host(m_hostname)
       << uri::port(m_port)
       << uri::path(m_path);

   // create a request instance and configure the headers
   client::request request(url);
   request << header("Connection", "close");
   request << header("Content-Type", "application/x-www-form-urlencoded");

   // send the request
   client::response response = httpClient.post(request, "foo=bar");
}

catch (std::exception& ex)
{
   ...
}

However, the following code results in a bad request.

client httpClient;

try
{
   uri::uri url;
   url << uri::scheme("http")
       << uri::host(m_hostname)
       << uri::port(m_port)
       << uri::path(m_path)
       << uri::query("foo", "bar");

  // create a request instance and configure the headers
   client::request request(url);
   request << header("Connection", "close");
   request << header("Content-Type", "application/x-www-form-urlencoded");
   request << body("foo=bar");

   // send the request
   client::response response = httpClient.post(request);
}

catch (std::exception& ex)
{
   ...
}

Please can someone explain what I'm doing wrong in the second example and which is the preferred option.

So you want to send a request with empty body?

tonso
– tonso

2015-03-12 10:40:05 +00:00
Commented Mar 12, 2015 at 10:40 — tonso
– tonso, Commented Mar 12, 2015 at 10:40
No, I want the body to be "foo=bar". Why do you ask that?

ksl
– ksl

2015-03-12 10:43:20 +00:00
Commented Mar 12, 2015 at 10:43 — ksl
– ksl, Commented Mar 12, 2015 at 10:43

tonso · Accepted Answer · 2015-03-12 11:11:09Z

4

Then you should add something like:

// ...
request << header("Content-Type", "application/x-www-form-urlencoded");
request << body("foo=bar");

otherwise you don't specify body anywhere.

EDIT: Also try adding something like:

std::string body_str = "foo=bar";
char body_str_len[8];
sprintf(body_str_len, "%u", body_str.length());
request << header("Content-Length", body_str_len);

before

 request << body(body_str);

edited Mar 12, 2015 at 11:11

answered Mar 12, 2015 at 10:44

tonso

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4 Comments

ksl Over a year ago

OK I see that I need to add the body to the request. However, that still doesn't work.

tonso Over a year ago

@ksl I expanded my post

ksl Over a year ago

Thanks @id256. That was it. I'd like to send multiple values - do you know if I have to format the key-value pairs myself (i.e. separate each with a '&') or is there a function to do it for me?

tonso Over a year ago

I'd use std::accumulate function from STL algorithm passing an instance of something like struct append_fun { std::string operator()(const std::string& s1, const std::string& s2) { return s1+"&"+s2; } } as BinaryOperation parameter.

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