How to create HTTP request using form-data in QT

[HemantSuryawanshi]

I am trying to sent an HTTP request to server with key-value pair form-data in it. but I think I missing something while sending request that's why I didn't receive the correct response from server and I am not able to get whats missing in it.

I have an API which generates terrain data and create its file. Here is my curl request

curl --location --request POST 'http://abc.xyz.com:123/generate' \
--header 'Content-Type;' \
--header 'Authorization: Bearer xxxxxxxx-xxxxxxx-xxxxxxx-xxx-xxx-xx-xxxxx' \
--form 'lat="19.3"' \
--form 'long="73.20"' \
--form 'radius="5"'

when I hit the request from postman it gives correct output but when I hit api from code it gives me "\n" as response.

Here is my code for same in QT

void RestApiHelper::generateTerrainData(float lat, float lon, qint32 radius)
{
    QUrl targateUrl = m_apiUrlHelper->getGenerateTerrainURL();
    qDebug() << targateUrl;
    QNetworkRequest request;
    request.setUrl(targateUrl);

    QString data = "xxxxx-xxxxxxx-xxxxxxxxx-xxxxxxxx";
    QString headerData = m_apiUrlHelper->getApiAuthorizationType() + data;
    request.setRawHeader( "Authorization", headerData.toLocal8Bit());
    qDebug() << "headerData :" << headerData.toLocal8Bit();

    QByteArray payload;
    payload.append("lat", lat);
    payload.append("long", lon);
    payload.append("radius", radius);

    QHttpMultiPart *multiPart = new QHttpMultiPart(QHttpMultiPart::FormDataType);
    QHttpPart textPart;
    //textPart.setHeader(QNetworkRequest::ContentTypeHeader, QVariant("form-data"));
    textPart.setHeader(QNetworkRequest::ContentDispositionHeader, QVariant("form-data; name=\"text\""));
    textPart.setBody(payload);
    multiPart->append(textPart);

    QNetworkAccessManager *restclient;
    restclient = new QNetworkAccessManager();
    //restclient->post(request,multiPart);
    QNetworkReply *reply = restclient->post(request, multiPart);
    multiPart->setParent(reply);

    disconnect(&m_generateTerrainProcessor, SIGNAL(dataReady(QString)), this, nullptr);
    connect(restclient, SIGNAL(finished(QNetworkReply*)), &m_generateTerrainProcessor, SLOT(handleAPIResponse(QNetworkReply*)));
    connect(&m_generateTerrainProcessor, SIGNAL(dataReady(QString)), this, SLOT(handleDataReady(QString)));
}

Here I sent data in kay/value pair to QByteArray and set this body to multiport. I tried with this way but didnt get expected result. The expected result is link of a generated file.

can anyone please tell me what I am doing wrong or is there any other method to assign kay-value pair form-data to the request in QT.

[raven-worx]

@HemantSuryawanshi said in How to create HTTP request using form-data in QT:

QByteArray payload;
payload.append("lat", lat);
payload.append("long", lon);
payload.append("radius", radius);

this does not create a key/value pair!

[JoeCFD]

    auto json_obj = createJsonObject( key, double_data );
    QJsonDocument json_document;
    json_document.setObject( json_obj );
    post( json_document.toJson() );

auto MyClass::createJsonObject( const QString & key, const double value ) ->QJsonObject
{
QJsonObject final_json_obj;
final_json_obj.insert( key, QJsonValue( value ) );
...........
}

[raven-worx]

@JoeCFD
how is this related?

[JoeCFD]

@raven-worx Use json to create key/value pairs and then convert it to QByteArray. That is how I do HTTP request.

[raven-worx]

@JoeCFD
thats how you do http requests on most REST interfaces, yes.
form encoded data is plain key value pairs, not json.

[JoeCFD]

@raven-worx Sorry. I did not read his code properly.

Does this linlk help?
https://forum.qt.io/topic/56708/solved-qnetworkaccessmanager-adding-a-multipart-form-data-to-a-post-request/6

[HemantSuryawanshi]

@raven-worx @JoeCFD thanks for your replies. I also tried with json before but get same output.
@JoeCFD I also referred the link you stated before. its for sending file. but I don't want to send a file, I just want to send key/value pair data using form-data.
can you please tell me how can I do this in Qt.

[Bonnie]

If your form-data is just plain text you should be able to do that by setting ContentTypeHeader to "application/x-www-form-urlencoded" and then just post a query string, instead of using QHttpMultiPart. Something like

request.setHeader(QNetworkRequest::ContentTypeHeader,"application/x-www-form-urlencoded");
restclient->post(request, "lat=19.3&long=73.20&radius=5");

[HemantSuryawanshi]

@Bonnie it worked. Thanks for your response