Multipart upload problem

[AxelVienna]

Dear all,
I have to replace a CURL function for multipart upload by QHttpMultipart.
The example in the documentation does not work for my case and I just can't get it running.
Your help is highly appreciated.
Thanks in advance, Axel

Original CURL based code:

    CURL *curl;
    CURLcode res;

    struct curl_httppost *formpost = NULL;
    struct curl_httppost *lastptr = NULL;
    struct curl_slist *headerlist = NULL;
    static const char buf[] =  "Expect:";

    curl_global_init(CURL_GLOBAL_ALL);

    // set up the header
    curl_formadd(&formpost,
        &lastptr,
        CURLFORM_COPYNAME, "cache-control:",
        CURLFORM_COPYCONTENTS, "no-cache",
        CURLFORM_END);

    curl_formadd(&formpost,
        &lastptr,
        CURLFORM_COPYNAME, "content-type:",
        CURLFORM_COPYCONTENTS, "multipart/form-data",
        CURLFORM_END);

    curl_formadd(&formpost,
        &lastptr,
        CURLFORM_COPYNAME, "part1",
        CURLFORM_COPYCONTENTS, "dummyname.csv",
        CURLFORM_END);

    curl_formadd(&formpost, &lastptr,
        CURLFORM_COPYNAME, "part2",
        CURLFORM_BUFFER, "data",
        CURLFORM_BUFFERPTR, contents.data(),
        CURLFORM_BUFFERLENGTH, contents.size(),
        CURLFORM_END);

    curl = curl_easy_init();

    string authkey = "apikey: " + get_apikey();
    headerlist = curl_slist_append(headerlist, authkey.c_str());
    headerlist = curl_slist_append(headerlist, buf);
    string readBuffer;
    if (curl) {

        curl_easy_setopt(curl, CURLOPT_URL, url.c_str());
        curl_easy_setopt(curl, CURLOPT_HTTPHEADER, headerlist);

        curl_easy_setopt(curl, CURLOPT_HTTPPOST, formpost);
        curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, writeFunction);
        curl_easy_setopt(curl, CURLOPT_WRITEDATA, &readBuffer);
        curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L);

        res = curl_easy_perform(curl);

New code which does not work:

    const string url = URL + "upload?file=" + filekey;

    QHttpMultiPart *multiPart = new QHttpMultiPart(QHttpMultiPart::FormDataType);
    QHttpPart cachePart;
    cachePart.setRawHeader("cache-control:", "no-cache");
    QHttpPart contentType;
    contentType.setRawHeader("content-type:", "multipart/form-data");
    QHttpPart fileName;
    fileName.setRawHeader("part1", "dummyname.csv");
    QHttpPart data;
    data.setRawHeader("part2", "data");
    data.setBody(QByteArray(contents.c_str()));

    multiPart->append(cachePart);
    multiPart->append(contentType);
    multiPart->append(fileName);
    multiPart->append(data);

    QUrl u((URL+"upload").c_str());
    QUrlQuery q;
    q.addQueryItem("file",filekey.c_str());
    u.setQuery(q);
    QNetworkRequest request(u);
    request.setRawHeader("apikey",get_apikey().c_str());

    QNetworkAccessManager* nm= new QNetworkAccessManager;
    auto reply = nm->post(request, multiPart);
    multiPart->setParent(reply); // delete the multiPart with the reply

    QEventLoop loop;
    QObject::connect(reply, &QNetworkReply::finished, &loop, &QEventLoop::quit);
    loop.exec();

    bool success = (reply->error()==QNetworkReply::NoError);
    string r = reply->readAll().toStdString();
    delete reply;
    return success;

[J.Hilk]

@AxelVienna
please don't force synchronous behaviour on asynchronous apis

QEventLoop loop;
    QObject::connect(reply, &QNetworkReply::finished, &loop, &QEventLoop::quit);
    loop.exec();

That's inviting all kinds of strange behaviour and hard to track down bugs.

[SGaist]

Hi,

What exact error do you get ?

Why are you creating one part per raw header ? That looks off.

[AxelVienna]

Hi SGaist,
thanks for looking into the issue. I did not get any error message. The code misbehaved and just did not upload any data.
With some trial and error and your advice not to set raw headers, I got it working with the code attached.
The issue is solved, I just have not gotten any wiser.
Brgds
Axel

 const string url = URL + "upload?file=" + filekey;

    QHttpMultiPart *multiPart = new QHttpMultiPart(QHttpMultiPart::FormDataType);
    QHttpPart cachePart;
    cachePart.setHeader(QNetworkRequest::ContentDispositionHeader, QVariant("form-data; name=\"cache-control:\""));
    cachePart.setBody("no-nache");
    QHttpPart contentType;
    contentType.setHeader(QNetworkRequest::ContentDispositionHeader, QVariant("form-data; name=\"content-type:\""));
    contentType.setBody("multipart/form-data");
    QHttpPart fileName;
    fileName.setHeader(QNetworkRequest::ContentDispositionHeader, QVariant("form-data; name=\"part1\""));
    fileName.setBody("dummyname.csv");
    QHttpPart data;
    data.setHeader(QNetworkRequest::ContentDispositionHeader, QVariant("form-data; name=\"part2\""));
    data.setBody(QByteArray(contents.c_str()));

    multiPart->append(cachePart);
    multiPart->append(contentType);
    multiPart->append(fileName);
    multiPart->append(data);

    QUrl u((URL+"upload").c_str());
    QUrlQuery q;
    q.addQueryItem("file",filekey.c_str());
    u.setQuery(q);
    QNetworkRequest request(u);
    request.setRawHeader("apikey",get_apikey().c_str());

    QNetworkAccessManager* nm= new QNetworkAccessManager;
    auto reply = nm->post(request, multiPart);
    multiPart->setParent(reply); // delete the multiPart with the reply

    QEventLoop loop;
    QObject::connect(reply, &QNetworkReply::finished, &loop, &QEventLoop::quit);
    loop.exec();

[J.Hilk]

@AxelVienna
please don't force synchronous behaviour on asynchronous apis

QEventLoop loop;
    QObject::connect(reply, &QNetworkReply::finished, &loop, &QEventLoop::quit);
    loop.exec();

That's inviting all kinds of strange behaviour and hard to track down bugs.