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Storing data from QnetworkReply

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  • mrjjM mrjj

    @LeeH
    So what is not working ?
    You clearly read data into _ba.

    L Offline
    L Offline
    LeeH
    wrote on last edited by
    #35

    @mrjj

    but my data::get() I use to read _ba that i call from main() after downloading, is empty(""), where as if I read _ba from the slot inside the class I can see all my data

    L 1 Reply Last reply
    0
    • L LeeH

      @mrjj

      but my data::get() I use to read _ba that i call from main() after downloading, is empty(""), where as if I read _ba from the slot inside the class I can see all my data

      L Offline
      L Offline
      LeeH
      wrote on last edited by
      #36

      @LeeH

      You know I think It's best I just stick to saving to file, that seem's to be the only way I can be sure my data sticks around and can be used anywhere.... I thank everyone for their help, and apologize for wasting all of our time!

      A 1 Reply Last reply
      0
      • L LeeH

        @LeeH

        You know I think It's best I just stick to saving to file, that seem's to be the only way I can be sure my data sticks around and can be used anywhere.... I thank everyone for their help, and apologize for wasting all of our time!

        A Offline
        A Offline
        ambershark
        wrote on last edited by ambershark
        #37

        @LeeH Well here's your problem:

        QByteArray data::get(){
            qDebug() << _ba;
        }
        

        You don't return anything. You should have gotten at least a compiler warning from that.

        Anyway, just edit to be:

        QByteArray data::get(){
            qDebug() << _ba;
            return _ba;
        }
        

        And your data.get() will work.

        There is no reason to save the data to a file. You're just wasting resources on disk and slowing your app down for no reason.

        My L-GPL'd C++ Logger github.com/ambershark-mike/sharklog

        L 1 Reply Last reply
        2
        • L LeeH

          @jsulm

          Ok... so how should I use QIOdevice here:

          QObject::connect(QIODevice, SIGNAL(readyRead()), this, SLOT(output(QNetworkReply*)));
          

          i get error: "expecting primary expression before ',' token" and it can't be instantiated

          thanks

          jsulmJ Offline
          jsulmJ Offline
          jsulm
          Lifetime Qt Champion
          wrote on last edited by
          #38

          @LeeH said in Storing data from QnetworkReply:

          Ok... so how should I use QIOdevice here

          You use your QNetworkReply which is derived from QIODevice. And you cannot connect a class - you only can connect instances.
          Did you read the documentation? http://doc.qt.io/qt-5/qnetworkaccessmanager.html
          From there:

          QNetworkRequest request;
          request.setUrl(QUrl("http://qt-project.org"));
          request.setRawHeader("User-Agent", "MyOwnBrowser 1.0");
          
          QNetworkReply *reply = manager->get(request);
          connect(reply, SIGNAL(readyRead()), this, SLOT(slotReadyRead())); // THIS ONE
          connect(reply, SIGNAL(error(QNetworkReply::NetworkError)),
                  this, SLOT(slotError(QNetworkReply::NetworkError)));
          connect(reply, SIGNAL(sslErrors(QList<QSslError>)),
                  this, SLOT(slotSslErrors(QList<QSslError>)));
          

          https://forum.qt.io/topic/113070/qt-code-of-conduct

          L 1 Reply Last reply
          1
          • mrjjM Offline
            mrjjM Offline
            mrjj
            Lifetime Qt Champion
            wrote on last edited by
            #39

            @LeeH said in Storing data from QnetworkReply:

            data obj;
            obj.download();
            obj.get();

            Ahh, now i understand the confusion.
            It won't stay in obj.download() until download is finished,
            but return at once, as QNetwork classes are asynchronous

            Then you call obj.get() but no data is there, because it was not downloaded yet.

            So it do work, but not in the way you think it does :)

            1 Reply Last reply
            3
            • A ambershark

              @LeeH Well here's your problem:

              QByteArray data::get(){
                  qDebug() << _ba;
              }
              

              You don't return anything. You should have gotten at least a compiler warning from that.

              Anyway, just edit to be:

              QByteArray data::get(){
                  qDebug() << _ba;
                  return _ba;
              }
              

              And your data.get() will work.

              There is no reason to save the data to a file. You're just wasting resources on disk and slowing your app down for no reason.

              L Offline
              L Offline
              LeeH
              wrote on last edited by LeeH
              #40

              @ambershark

              Hi

              @ambershark said in Storing data from QnetworkReply:

              You don't return anything. You should have gotten at least a compiler warning from that.
              Anyway, just edit to be:
              QByteArray data::get(){
              qDebug() << _ba;
              return _ba;
              }

              Your right about returning _ba. I should have seen that as the function is not void... (my brains been fried working on real project lol), and I agree the compiler should have warned me about that. But that being said unfortunately has not resolved the problem. The output is still ""

              However in the same function If I deliberately overwrite _ba, I get output:

              QByteArray data::get(){
                  _ba = "testing...";
                  qDebug() << _ba;
                  return _ba;
              }
              

              output: "testing..."

              if I remove my call to data::get() in main() and output server data directly from the slot I get my data:

               if(!_rep->error()){
                    qDebug() << _ba.append(_rep->readAll());
               }
               else{
                      qDebug() << _rep->error();
               }
               _rep->deleteLater();
              

              There is no reason to save the data to a file. You're just wasting resources on disk and slowing your app down for no reason.

              Yep that was the reason for my post

              mrjjM J.HilkJ 2 Replies Last reply
              0
              • L LeeH

                @ambershark

                Hi

                @ambershark said in Storing data from QnetworkReply:

                You don't return anything. You should have gotten at least a compiler warning from that.
                Anyway, just edit to be:
                QByteArray data::get(){
                qDebug() << _ba;
                return _ba;
                }

                Your right about returning _ba. I should have seen that as the function is not void... (my brains been fried working on real project lol), and I agree the compiler should have warned me about that. But that being said unfortunately has not resolved the problem. The output is still ""

                However in the same function If I deliberately overwrite _ba, I get output:

                QByteArray data::get(){
                    _ba = "testing...";
                    qDebug() << _ba;
                    return _ba;
                }
                

                output: "testing..."

                if I remove my call to data::get() in main() and output server data directly from the slot I get my data:

                 if(!_rep->error()){
                      qDebug() << _ba.append(_rep->readAll());
                 }
                 else{
                        qDebug() << _rep->error();
                 }
                 _rep->deleteLater();
                

                There is no reason to save the data to a file. You're just wasting resources on disk and slowing your app down for no reason.

                Yep that was the reason for my post

                mrjjM Offline
                mrjjM Offline
                mrjj
                Lifetime Qt Champion
                wrote on last edited by mrjj
                #41

                @LeeH
                You did read why it dont work ?
                obj.download();
                obj.get();
                Cannot work as download() is not a blocking call
                so you will call obj.get(); BEFORE any data ever is read.

                First when you get signal, its safe to use obj.get(); Not before.

                1 Reply Last reply
                3
                • L LeeH

                  @ambershark

                  Hi

                  @ambershark said in Storing data from QnetworkReply:

                  You don't return anything. You should have gotten at least a compiler warning from that.
                  Anyway, just edit to be:
                  QByteArray data::get(){
                  qDebug() << _ba;
                  return _ba;
                  }

                  Your right about returning _ba. I should have seen that as the function is not void... (my brains been fried working on real project lol), and I agree the compiler should have warned me about that. But that being said unfortunately has not resolved the problem. The output is still ""

                  However in the same function If I deliberately overwrite _ba, I get output:

                  QByteArray data::get(){
                      _ba = "testing...";
                      qDebug() << _ba;
                      return _ba;
                  }
                  

                  output: "testing..."

                  if I remove my call to data::get() in main() and output server data directly from the slot I get my data:

                   if(!_rep->error()){
                        qDebug() << _ba.append(_rep->readAll());
                   }
                   else{
                          qDebug() << _rep->error();
                   }
                   _rep->deleteLater();
                  

                  There is no reason to save the data to a file. You're just wasting resources on disk and slowing your app down for no reason.

                  Yep that was the reason for my post

                  J.HilkJ Offline
                  J.HilkJ Offline
                  J.Hilk
                  Moderators
                  wrote on last edited by
                  #42

                  @LeeH according to what @mrjj said:

                  QObject::connect(_rep, SIGNAL(readyRead()), this, SLOT(output()));
                  QObject::connect(_rep, SIGNAL(finished()), this, SLOT(get()));
                  

                  should do the trick.

                  get() will be called as soon as all data is written into the Bytearray.


                  Be aware of the Qt Code of Conduct, when posting : https://forum.qt.io/topic/113070/qt-code-of-conduct


                  Q: What's that?
                  A: It's blue light.
                  Q: What does it do?
                  A: It turns blue.

                  1 Reply Last reply
                  2
                  • jsulmJ jsulm

                    @LeeH said in Storing data from QnetworkReply:

                    Ok... so how should I use QIOdevice here

                    You use your QNetworkReply which is derived from QIODevice. And you cannot connect a class - you only can connect instances.
                    Did you read the documentation? http://doc.qt.io/qt-5/qnetworkaccessmanager.html
                    From there:

                    QNetworkRequest request;
                    request.setUrl(QUrl("http://qt-project.org"));
                    request.setRawHeader("User-Agent", "MyOwnBrowser 1.0");
                    
                    QNetworkReply *reply = manager->get(request);
                    connect(reply, SIGNAL(readyRead()), this, SLOT(slotReadyRead())); // THIS ONE
                    connect(reply, SIGNAL(error(QNetworkReply::NetworkError)),
                            this, SLOT(slotError(QNetworkReply::NetworkError)));
                    connect(reply, SIGNAL(sslErrors(QList<QSslError>)),
                            this, SLOT(slotSslErrors(QList<QSslError>)));
                    
                    L Offline
                    L Offline
                    LeeH
                    wrote on last edited by LeeH
                    #43

                    Hi
                    I had already modified my code in earlier post. You suggested QIODevice doc for readyRead() but I didn't realise QNetworkReply also had a readRead signal.

                    @jsulm said in Storing data from QnetworkReply:

                    You should connect your output() slot to http://doc.qt.io/qt-5/qiodevice.html#readyRead signal.

                    1 Reply Last reply
                    0
                    • L Offline
                      L Offline
                      LeeH
                      wrote on last edited by LeeH
                      #44

                      Hi guys

                      Ah at last it now works! When I did what @mrjj said:

                      Cannot work as download() is not a blocking call
                      so you will call obj.get(); BEFORE any data ever is read.

                      and then what @J.Hilk said after making data::get() a slot:

                      QObject::connect(_rep, SIGNAL(readyRead()), this, SLOT(output()));
                      QObject::connect(_rep, SIGNAL(finished()), this, SLOT(get()));
                      

                      Success... Thanks so much to EVERYONE that helped!

                      Lee

                      1 Reply Last reply
                      3
                      • mrjjM Offline
                        mrjjM Offline
                        mrjj
                        Lifetime Qt Champion
                        wrote on last edited by
                        #45

                        Super.
                        Good work not giving up.

                        1 Reply Last reply
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