Sending an image using Poco to a webserver - c++

Question

I'm trying to upload a picture to appengine using POCO::Net::HTMLForm.
Please see the code below. The problem I have is that the imagedata is not send. The token and the character name (its for an open source action rpg) is transmited without any problem. Any idea what I may do wrong?
Thanks in advance :)
c++ code:
// prepare session
Poco::URI uri(backend_url + "/api/update_character_avatar");
Poco::Net::HTTPClientSession session(uri.getHost(), uri.getPort());
// prepare path
std::string path(uri.getPathAndQuery());
if (path.empty()) path = "/";
Poco::Net::HTTPRequest req(Poco::Net::HTTPRequest::HTTP_POST, path);
Poco::Net::HTMLForm form;
form.add("token", sw_token);
form.add("charname", sw_charname);
Poco::Buffer<char> imgBuffer(mImgPtr->size());
mImgPtr->read(imgBuffer.begin(), imgBuffer.end()-imgBuffer.begin());
std::string s(imgBuffer.begin(), mImgPtr->size());
std::ostringstream out;
Poco::Base64Encoder b64enc(out);
b64enc.write(imgBuffer.begin(), imgBuffer.end()-imgBuffer.begin());
b64enc.close();
Poco::Net::StringPartSource *prtsrc = new Poco::Net::StringPartSource(out.str());
form.addPart("imagedata", prtsrc);
form.prepareSubmit(req);
std::ostream& send = session.sendRequest(req);
form.write(send);
// get response
Poco::Net::HTTPResponse res;
// print response
std::istream &is = session.receiveResponse(res);
std::ostringstream stream;
Poco::StreamCopier::copyStream(is, stream);
std::cout << stream.str() << std::endl;
Python handler for appengine:
class UpdateCharacterAvatarHandler(webapp2.RequestHandler):
def post(self):
token = self.request.get("token")
charname = self.request.get("charname")
imagedata = self.request.get("imagedata")
logging.error(self.request.body)
self.response.write("test")

Answer 1

Sorry I couldn't understand what exactly you are trying to do in this code. There are lot of useless steps you have taken to upload a file as it can be done simply by using HTMLForm class. Here are the minimum code required to do so -
HTTPRequest request(HTTPRequest::HTTP_POST, "/fileupload/upload_file.php", HTTPMessage::HTTP_1_1);
HTMLForm form;
form.setEncoding(HTMLForm::ENCODING_MULTIPART);
form.addPart("file", new FilePartSource("/home/abc/Pictures/sample.png"));
form.prepareSubmit(request);
HTTPClientSession *httpSession = new HTTPClientSession("localhost");
httpSession->setTimeout(Poco::Timespan(20, 0));
form.write(httpSession->sendRequest(request));
Poco::Net::HTTPResponse res;
std::istream &is = httpSession->receiveResponse(res);
Poco::StreamCopier::copyStream(is, std::cout);
The corresponding upload server is using standard PHP code for uploading HTML form files.

Answer 2

I would expect imagedata to appear as a post field rather than get, so I would try     imagedata = self.request.post("imagedata"). Alternatively try posting it to a server which will allow you to set breakpoints and inspect the content of the request.