Invalid data while uploading Image with Imgur API - c++

Question

I want to upload a PNG image with the Imgur API. When I converted a test image (png) to Base64, I got an error that it was not a valid file type. Then I took the test image from the Imgur API documentation (R0lGODlhAQABAIAAAAAAAP//yH5BAEAAAAALAAAABAAEAAAIBRAA7), which worked for an upload, converted it to a "real" image via a converter and tested a Base64 conversion with it. However, I get a different Base64 string (R0lGODlhAQABAOKCrAAAAAAAw7/Dv8O/IcO5BAEAAAAALAAAAAABAAEAAAIBRAA7).
Code snippet:
QNetworkAccessManager *manager = new QNetworkAccessManager(this);
QUrl url("https://api.imgur.com/3/image");
QNetworkRequest request(url);
request.setRawHeader("Authorization", "Client-ID <hereIsTheClientID>");
request.setHeader(QNetworkRequest::ContentTypeHeader, "application/x-www-form-urlencoded");
QFile image ("C:/Users/pietr/Desktop/image.gif"); // Result from converting example Base64 from Imgur API-Docs - this file can be read by photo viewers
image.open(QIODevice::ReadOnly);
QTextStream in (&image);
QByteArray imageArray = in.readAll().toUtf8().toBase64();
qDebug() << "Image data:" << imageArray;
QUrlQuery params;
params.addQueryItem("image", imageArray);
connect(manager, SIGNAL(finished(QNetworkReply*)), this, SLOT(replyFinished(QNetworkReply*)));
manager->post(request, params.query().toUtf8());
But the reply is...
{
"data":
{
"error":
{
"code":1003,
"message":"File type invalid (2)",
"type":"ImgurException",
"exception":[]},"request":"\/3\/image",
"method":"POST"
},
"success":false,
"status":400
}
Am I making a mistake with the Base64 convert? Why do I get a different value out of the same images?

Answer 1

The image is not sent in the query but as form-data. Using an old answer and applied in your case the solution is:
#include <QCoreApplication>
#include <QFile>
#include <QHttpMultiPart>
#include <QNetworkAccessManager>
#include <QNetworkReply>
QHttpMultiPart *buildMultpart(const QVariantMap & data, const QMap<QString, QString> filenames){
QHttpMultiPart *multipart = new QHttpMultiPart(QHttpMultiPart::FormDataType);
QVariantMap::const_iterator i_data = data.constBegin();
while (i_data != data.constEnd()) {
QHttpPart postpart;
postpart.setHeader(QNetworkRequest::ContentDispositionHeader, QString("form-data; name=\"%1\"").arg(i_data.key()));
postpart.setBody(i_data.value().toByteArray());
multipart->append(postpart);
++i_data;
}
QMap<QString, QString>::const_iterator i_filenames = filenames.constBegin();
while (i_filenames != filenames.constEnd()) {
QFile *file = new QFile(i_filenames.value());
if(!file->open(QIODevice::ReadOnly)){
delete file;
continue;
}
QHttpPart postpart;
postpart.setHeader(QNetworkRequest::ContentDispositionHeader,
QString("form-data; name=\"%1\"; filename=\"%2\"")
.arg(i_filenames.key(), file->fileName()));
postpart.setBodyDevice(file);
multipart->append(postpart);
file->setParent(multipart);
++i_filenames;
}
return multipart;
}
int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);
const QString CLIENT_ID = QLatin1String("{{clientId}}");
const QString API_URL = QLatin1String("https://api.imgur.com");
QNetworkAccessManager manager;
QNetworkRequest request;
QUrl url(API_URL);
url.setPath("/3/upload");
request.setUrl(url);
request.setRawHeader("Authorization", ("Client-ID "+ CLIENT_ID).toUtf8());
QMap<QString, QString> filenames;
filenames["image"] = "C:/Users/pietr/Desktop/image.gif";
QHttpMultiPart *multipart = buildMultpart({}, filenames);
QNetworkReply *reply = manager.post(request, multipart);
multipart->setParent(reply);
QObject::connect(reply, &QNetworkReply::finished, [reply](){
if(reply->error() == QNetworkReply::NoError){
qDebug().noquote() << reply->readAll();
}
else{
qDebug() << reply->error() << reply->errorString();
}
reply->deleteLater();
QCoreApplication::quit();
});
return a.exec();
}
Output:
{"status":200,"success":true,"data":{"id":"iT63Heu","deletehash":"JRIdjdWP7lMhzuG","account_id":null,"account_url":null,"ad_type":null,"ad_url":null,"title":null,"description":null,"name":"","type":"image/gif","width":100,"height":75,"size":6166,"views":0,"section":null,"vote":null,"bandwidth":0,"animated":false,"favorite":false,"in_gallery":false,"in_most_viral":false,"has_sound":false,"is_ad":false,"nsfw":null,"link":"https://i.imgur.com/iT63Heu.gif","tags":[],"datetime":1634600948,"mp4":"","hls":""}}
If you want to use base64 then change to:
// ...
request.setRawHeader("Authorization", ("Client-ID "+ CLIENT_ID).toUtf8());
QVariantMap data;
QFile image("C:/Users/pietr/Desktop/image.gif");
if(image.open(QIODevice::ReadOnly)){
data["image"] = image.readAll().toBase64();
data["type"] = "base64";
image.close();
}
QHttpMultiPart *multipart = buildMultpart(data, {});
QNetworkReply *reply = manager.post(request, multipart);
// ...