Post JSON request in Qt 4.7

[haxuanthao]

I'm working on a project required me to post JSON request to API server then receive data from server. However I cannot make it work. This is my code

MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    QUrl serviceUrl = QUrl("https://www.jusmine.jp/KA/KGBloginCheck");
    QNetworkRequest request(serviceUrl);
    QJsonObject json;
    json.insert("userid","xxxx");
    json.insert("userpass","xxxx");     
    request.setHeader(QNetworkRequest::ContentTypeHeader,"application/json");
    request.setHeader(QNetworkRequest::ContentLengthHeader,QByteArray::number(json.size()));
    QNetworkAccessManager *networkManager = new QNetworkAccessManager(this);
    connect(networkManager,SIGNAL(finished(QNetworkReply*)),this,SLOT(serviceRequestFinish(QNetworkReply*)));
    networkManager->post(request,QJsonDocument(json).toJson());
}
void MainWindow::serviceRequestFinish(QNetworkReply *rep)
{
    QString strReply = (QString)rep->readAll();
    qDebug()<<"Test: "<<strReply;
}

MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    QUrl serviceUrl = QUrl("https://www.jusmine.jp/KA/KGBloginCheck");
    QNetworkRequest request(serviceUrl);
    QJsonObject json;
    json.insert("userid","xxxx");
    json.insert("userpass","xxxx");     
    request.setHeader(QNetworkRequest::ContentTypeHeader,"application/json");
    request.setHeader(QNetworkRequest::ContentLengthHeader,QByteArray::number(json.size()));
    QNetworkAccessManager *networkManager = new QNetworkAccessManager(this);
    connect(networkManager,SIGNAL(finished(QNetworkReply*)),this,SLOT(serviceRequestFinish(QNetworkReply*)));
    networkManager->post(request,QJsonDocument(json).toJson());
}
void MainWindow::serviceRequestFinish(QNetworkReply *rep)
{
    QString strReply = (QString)rep->readAll();
    qDebug()<<"Test: "<<strReply;
}

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After running the program I get nothing from server. (This code is built on Qt 4.7.0 so I have to use library qjson4-master). I don't know if any one can help me in this problem.
This is the result of testing server API:
Untitled.jpg
Thank you!

[ChrisW67]

QJsonObject::size() does not return the size of the encoded QJsonDocument object. Leave that header out entirely: QNetworkAccessManager::post() will set it for you.