title: boost beast sample to send post
body: <p>I'm getting the following response and I don't know how to identify the problem.  Fiddler doesn't capture anything so I believe the request is not being sent out.</p>
  
  <p><code>
      HTTP/1.1 411 Length Required
      Content-Type: text/html; charset=us-ascii
      Server: Microsoft-HTTPAPI/2.0
      Date: Wed, 22 May 2019 11:15:04 GMT
      Connection: close
      Content-Length: 344
  </code></p>
  
  <p>I've attempted to follow the other examples I've found, but it seems setting the body no longer compiles.</p>
  
  <p><code>
      // error C2679: binary '=': no operator found which takes a right-hand operand of type 'const char *' (or there is no acceptable conversion)
      req_.body() = "test";
  </code></p>
  
  <p>I'm using Visual Studio 2017 compiled for x64 with Boost linked as DLLs.  I started with the beast samples and got "GET" to work perfectly for me.  I'm having problems getting "POST" to work from the beast client</p>
  
  <p>`</p>
  
  <pre><code>//
  // Example: HTTP client, asynchronous
  //
  
  // Quickly add boost DLLs with: https://www.nuget.org/packages/boost-vc141/
  
  #include &lt;boost/beast/core.hpp&gt;
  #include &lt;boost/beast/http.hpp&gt;
  #include &lt;boost/beast/version.hpp&gt;
  #include &lt;boost/asio/strand.hpp&gt;
  #include &lt;boost/property_tree/ptree.hpp&gt;
  #include &lt;boost/property_tree/json_parser.hpp&gt;
  #include &lt;boost/lexical_cast.hpp&gt;
  #include &lt;cstdlib&gt;
  #include &lt;functional&gt;
  #include &lt;iostream&gt;
  #include &lt;memory&gt;
  #include &lt;string&gt;
  
  namespace beast = boost::beast;         // from &lt;boost/beast.hpp&gt;
  namespace http = beast::http;           // from &lt;boost/beast/http.hpp&gt;
  namespace net = boost::asio;            // from &lt;boost/asio.hpp&gt;
  using tcp = boost::asio::ip::tcp;       // from &lt;boost/asio/ip/tcp.hpp&gt;
  
  // Report a failure
  void
  fail(beast::error_code ec, char const* what)
  {
      std::cerr &lt;&lt; what &lt;&lt; ": " &lt;&lt; ec.message() &lt;&lt; "\n";
  }
  
  // Performs an HTTP GET and prints the response
  class session : public std::enable_shared_from_this&lt;session&gt;
  {
      tcp::resolver resolver_;
      beast::tcp_stream stream_;
      beast::flat_buffer buffer_; // (Must persist between reads)
      http::request&lt;http::dynamic_body&gt; req_;
      http::response&lt;http::string_body&gt; res_;
  
  public:
      // Objects are constructed with a strand to
      // ensure that handlers do not execute concurrently.
      explicit
          session(net::io_context&amp; ioc)
          : resolver_(net::make_strand(ioc))
          , stream_(net::make_strand(ioc))
      {
      }
  
      // Start the asynchronous operation
      void
          run(
              char const* host,
              char const* port,
              char const* target,
              char const* body,
              int version)
      {
          // Set up an HTTP POST request message
          req_.version(version);
          req_.method(http::verb::post);
          req_.target(target);
          req_.set(http::field::host, host);
          req_.set(http::field::user_agent, BOOST_BEAST_VERSION_STRING);
          req_.set(http::field::content_length, boost::lexical_cast&lt;std::string&gt;(strlen(body)));
          req_.set(http::field::body, body);
          req_.prepare_payload();
  
          // following line doesn't compile:
          // error C2679: binary '=': no operator found which takes a right-hand operand of type 'const char *' (or there is no acceptable conversion)
          //req_.body() = body;
  
          // Look up the domain name
          resolver_.async_resolve(
              host,
              port,
              beast::bind_front_handler(
                  &amp;session::on_resolve,
                  shared_from_this()));
      }
  
      void
          on_resolve(
              beast::error_code ec,
              tcp::resolver::results_type results)
      {
          if (ec)
              return fail(ec, "resolve");
  
          // Set a timeout on the operation
          stream_.expires_after(std::chrono::seconds(30));
  
          // Make the connection on the IP address we get from a lookup
          stream_.async_connect(
              results,
              beast::bind_front_handler(
                  &amp;session::on_connect,
                  shared_from_this()));
      }
  
      void
          on_connect(beast::error_code ec, tcp::resolver::results_type::endpoint_type)
      {
          if (ec)
              return fail(ec, "connect");
  
          // Set a timeout on the operation
          stream_.expires_after(std::chrono::seconds(30));
  
          // Send the HTTP request to the remote host
          http::async_write(stream_, req_,
              beast::bind_front_handler(
                  &amp;session::on_write,
                  shared_from_this()));
      }
  
      void
          on_write(
              beast::error_code ec,
              std::size_t bytes_transferred)
      {
          boost::ignore_unused(bytes_transferred);
  
          if (ec)
              return fail(ec, "write");
  
          // Receive the HTTP response
          http::async_read(stream_, buffer_, res_,
              beast::bind_front_handler(
                  &amp;session::on_read,
                  shared_from_this()));
      }
  
      void
          on_read(
              beast::error_code ec,
              std::size_t bytes_transferred)
      {
          boost::ignore_unused(bytes_transferred);
  
          if (ec)
              return fail(ec, "read");
  
          // Write the message to standard out
          std::cout &lt;&lt; res_ &lt;&lt; std::endl;
  
          // Gracefully close the socket
          stream_.socket().shutdown(tcp::socket::shutdown_both, ec);
  
          // not_connected happens sometimes so don't bother reporting it.
          if (ec &amp;&amp; ec != beast::errc::not_connected)
              return fail(ec, "shutdown");
  
          // If we get here then the connection is closed gracefully
      }
  };
  
  std::string create_body()
  {
      boost::property_tree::ptree tree;
      tree.put("foo", "bar");
      std::basic_stringstream&lt;char&gt; jsonStream;
      boost::property_tree::json_parser::write_json(jsonStream, tree, false);
      return jsonStream.str();
  }
  
  int main(int argc, char** argv)
  {
      // Check command line arguments.
      if (argc != 4 &amp;&amp; argc != 5)
      {
          std::cerr &lt;&lt;
              "Usage: http-client-async &lt;host&gt; &lt;port&gt; &lt;target&gt; [&lt;HTTP version: 1.0 or 1.1(default)&gt;]\n" &lt;&lt;
              "Example:\n" &lt;&lt;
              "    http-client-async www.example.com 80 /\n" &lt;&lt;
              "    http-client-async www.example.com 80 / 1.0\n";
          return EXIT_FAILURE;
      }
      auto const host = argv[1];
      auto const port = argv[2];
      auto const target = argv[3];
      int version = argc == 5 &amp;&amp; !std::strcmp("1.0", argv[4]) ? 10 : 11;
  
      // The io_context is required for all I/O
      net::io_context ioc;
  
      // Launch the asynchronous operation
      std::make_shared&lt;session&gt;(ioc)-&gt;run(host, port, target, create_body().c_str(), version);
  
      // Run the I/O service. The call will return when
      // the get operation is complete.
      ioc.run();
  
      return EXIT_SUCCESS;
  }
  </code></pre>
  
  <p>`</p>
  
  <ol>
  <li>How do I see what beast is generating as the packet to be sent?</li>
  <li>How do I fix the compilation error attempting to set the body as shown in other posts: <code>request.body() = "bodytext";</code></li>
  <li>Can someone provide a sample beast client &amp; server that uses post?</li>
  </ol>