QNetworkAccessManager finished signal error



  • I want to download a token from server, I download files from the server before but this time the only change is the code is in a new header and source file.

    updater.h :

    #ifndef UPDATER_H
    #define UPDATER_H
    
    #include <QObject>
    #include <QNetworkReply>
    #include <QSettings>
    
    class Updater : public QObject
    {
        Q_OBJECT // Enable slots and signals
    
    public:
        Updater();
        ~Updater();
    
    private slots:
        void getTokenFinished(QNetworkReply* replay);
    
    private:
        void getToken();
    
        void statusCheck();
    
        QString token;
    
        QSettings settings;
    };
    
    #endif // UPDATER_H
    
    

    updater.cpp :

    #include "updater.h"
    
    #include <QDebug>
    #include <QNetworkAccessManager>
    
    Updater::Updater()
    {
        this->getToken();
    }
    
    Updater::~Updater()
    {
    
    }
    
    void Updater::getToken()
    {
        QNetworkAccessManager *manager = new QNetworkAccessManager(this);
        QNetworkRequest request;
    
        request.setUrl(QUrl("http://localhost/cdms/pro/index.php/update/token?version=3.14&"
                            "lisenceRegis=1&onlineRegis=1&parishId=1"));
    
        request.setRawHeader("User-Agent", "MyOwnBrowser 1.0");
        QNetworkReply *replay = manager->get(request);
        qDebug() << request.url();
    
        connect(manager, SIGNAL(finished(QNetworkReply*)),
                this, SLOT(getTokenFinished(QNetworkReply*)));
    }
    
    void Updater::getTokenFinished(QNetworkReply* replay)
    {
        qDebug() << "finished";
        // Checking replay
        if (replay->isReadable()) {
            // Checking errors
            if(replay->error() == QNetworkReply::NoError) {
                QByteArray strreplay = replay->readAll();
    
                qDebug() << strreplay;
                if(strreplay != "0") {
                    token = strreplay;
                    qDebug() << token;
                }
            }
        }
    }
    
    void Updater::statusCheck()
    {
    }
    
    

    php :

    $token = "dfsdfs";
    echo $token;
    

    No error in build or running the code. finished signal isn't emitted or 'void Updater::getTokenFinished(QNetworkReply* replay)' didn't run.



  • You should connect the readyRead() and error() signals of QNetworkReply *replay.

    Please see the documentation: http://doc.qt.io/qt-5/qnetworkaccessmanager.html



  • @ccleung but I don't get any signals



  • HI,

    is your request recevied from the running web server?

    What is your environment? (Qt version, OS, ...)



  • @mcosta I test the url on a browser and it worked, it's a LAMP server

    environment : Qt 5.4.1, Ubuntu 12.04

    the same code is run on main window class fine but I can't run the same network request on custom resource/header. I want to write the data updating section code on a different resource/header file.



  • Hi,

    when you run your Qt code, can you see the request on the server side? (apache access_log file for instance)?

    what about remove the custom header? something changes?


  • Lifetime Qt Champion

    Hi,

    Any chance of having something like:

    void MyCoolClass::getUpate()
    {
        Updater updater;
        updater.getToken();
    }
    

    ?



  • @mcosta Removed the header part but nothing on access log. I think the QNetworkAccessManager no even sending any request.



  • @SGaist No luck.



  • @SGaist @mcosta I think I got a clue, In

    void MyCoolClass::getUpate()
    {
         Updater updater;
         updater.getToken();
        
         this->runUpdate();
    }
    

    if I run both then only 'this->runUpdate();' call will work if commented out 'this->runUpdate();' then 'updater.getToken();' works.

    void MyCoolClass::runUpdate()
    {
        
        QNetworkAccessManager *manager = new QNetworkAccessManager(this);
        request.setUrl(QUrl("http://localhost/cdms/pro/index.php/update/linux?version=4.14&"
                            "lisenceRegis=1&onlineRegis=1"));
    
        QNetworkReply *reply = manager->get(request);
    
        connect(manager, SIGNAL(finished(QNetworkReply*)),
                this, SLOT(replyFinished(QNetworkReply*)));
    }
    
    
    void CDMS::replyFinished(QNetworkReply * replay)
    {
    
        // Checking replay
        if (replay->isReadable()) {
    
            // Checking errors
            if(replay->error() == QNetworkReply::NoError) {
                QByteArray strreplay = replay->readAll();
    
                // update ststus check
                if(strreplay != "0") {
                   } else {
                    ui->statusBar->showMessage("No new updates found", 10000);
    
                    // run update on intervel in 30Minute
                    QTimer::singleShot(1800000, this, SLOT(updateOnlineTimer()));
    
                   
                    // Run update on data and settings
                    //Updater updateCDMSdata;
                    //updateCDMSdata.getToken();
    
                }
    
            } else {
                ui->statusBar->showMessage(replay->errorString(), 10000);
    
                // run update on intervel in 1Minute
                QTimer::singleShot(60000, this, SLOT(updateOnlineTimer()));
            }
        }
    }
    

    I want to call the 'Updater' when the 'runUpdate' download finished.


  • Moderators

    You create a local instance of Updater in this method:

    void MyCoolClass::getUpate()
    {
         Updater updater;
         updater.getToken();
        
         this->runUpdate();
    }
    

    As soon as this method finishes updater goes out of scope and is destroyed. That's why nothing is called. You must keep the instance until it finishes its work.



  • Replace with this works fine

    void MyCoolClass::getUpate()
    {

     Updater *updateCDMSdata = new Updater;
    
     this->runUpdate();
    

    }


  • Moderators

    But now you have a memory leak: you do not delete updateCDMSdata


  • Lifetime Qt Champion

    To add to @jsulm, what does runUpdate do ? Call a function on updateCDMSdata ? If so you are lucky id doesn't crash.

    If you will be using Updater several times then make it a member of your MyCoolClass object and don't forget to handle its deletion.



  • @SGaist , runUpdate used to update the software and updateCDMSdata used to update data. I want to run data update when there is no software update, first check software update then from the 'finished(QNetworkReply*)' signal data update started.

    I need to call updater several times, so I think use Updater as a member and delete on MyCoolClass::~MyCoolClass() is a better idea ?


  • Lifetime Qt Champion

    Since it's a QObject you can use the parent/child paradigm to let Qt handle the deletion for you.


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