http request without signals and slots

[whites11]

hi all.
i'm a newbie in qt programmin, so please be patient.
i'm writing a qt library and i need to perform an http request to a remote server and, of course, read the response.
i don't need at all to use the signals and slots system, because i have to wait for the http call to finish before going on with the code.
is there a way to do that? i prefer to use the new network api, if possible

thanks

christian

[wysota]

Use QNetworkAccessManager together with QEventLoop.

[whites11]

thanks for the answer.

my "download" method is this (code found on the forum, i think it's posted by you):

QNetworkAccessManager* manager = new QNetworkAccessManager();
    QUrl murl = this->url;
    QNetworkReply *reply = manager->get(QNetworkRequest(url));
    QEventLoop loop;
    connect(reply, SIGNAL(finished()), &loop, SLOT(quit()));
    QTimer timer;
    connect(&timer, SIGNAL(timeout()), &loop, SLOT(quit())); // just in case
    timer.start(5000);
    loop.exec();
    QByteArray result = reply->readAll();
 
    if ( reply->error() != QNetworkReply::NoError ) {
        qDebug() << "Request failed:" << reply->errorString();
        return;
    }
 
    qDebug() << "Reply from the server: ";
    qDebug() << result;
}

QNetworkAccessManager* manager = new QNetworkAccessManager();
    QUrl murl = this->url;
    QNetworkReply *reply = manager->get(QNetworkRequest(url));
    QEventLoop loop;
    connect(reply, SIGNAL(finished()), &loop, SLOT(quit()));
    QTimer timer;
    connect(&timer, SIGNAL(timeout()), &loop, SLOT(quit())); // just in case
    timer.start(5000);
    loop.exec();
    QByteArray result = reply->readAll();

    if ( reply->error() != QNetworkReply::NoError ) {
        qDebug() << "Request failed:" << reply->errorString();
        return;
    }

    qDebug() << "Reply from the server: ";
    qDebug() << result;
}

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but when i run it i get:

QEventLoop: Cannot be used without QApplication
QObject::startTimer: QTimer can only be used with threads started with QThread

and the program loops

i'm writing a shared library, so there is not a QApplication. is there another way, then?

[wysota]

No, you need a Q(Core)Application object. Someone has to create it - either you when initializing your library or the application that uses your library.

[whites11]

thanks, declaring a QCoreApplication did the trick.
last quetion, is there a way to esatablish if a QCoreApplication exists before creating a new one? in that case i could create a qcoreapplication only if needed

[wysota]

QCoreApplication is a singleton, you can query for its instance through QCoreApplication::instance().

[whites11]

well wysota, thanks again
you have a beer payed if you pass here