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QNetworkAccessManager and POST return

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  • B Offline
    B Offline
    bsomervi
    wrote on last edited by
    #2

    QNetworkAccessManager is designed to work with the Qt event loop. It is event driven and it communications with you also by events. The QNetworkReply::finished() or QNetworkAccessManager::finished(QNetworkReply *) slots are not the only place results can be read, you can also connect the QNetworkReply::readReady() signal and get results incrementally as they stream in.

    H 1 Reply Last reply
    1
    • B bsomervi

      QNetworkAccessManager is designed to work with the Qt event loop. It is event driven and it communications with you also by events. The QNetworkReply::finished() or QNetworkAccessManager::finished(QNetworkReply *) slots are not the only place results can be read, you can also connect the QNetworkReply::readReady() signal and get results incrementally as they stream in.

      H Offline
      H Offline
      Helson
      wrote on last edited by
      #3

      @bsomervi
      Thanks for your elucidation.
      if it is not asking too much, you can show an example or something about?

      1 Reply Last reply
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      • H Helson

        Hello,

        networkMgr = new QNetworkAccessManager(this);
        connect(mpNetworkMgr, SIGNAL(finished(QNetworkReply*)), this, SLOT(onFinishedValidation(QNetworkReply*)));
        
        mpNetworkMgrSend->post(request, datatoSend);
        
        void MyClass::onFinishedValidation(QNetworkReply *reply)
        {
         	QString data = (QString) reply->readAll(); //It's works!
        }
        

        With this code I below I can't read the response:

        QNetworkReply* reply;
        reply = mpNetworkMgrSend->post(request, datatoSend);
        QString data = (QString) reply->readAll();
        
        

        Why the only way to read the response is inside the slot onFinishedValidation?
        Exist a way to read the response outside of slot or both?

        Thank you!

        jsulmJ Offline
        jsulmJ Offline
        jsulm
        Lifetime Qt Champion
        wrote on last edited by
        #4

        @Helson You cannot just read the response right after sending the post. The communication over network takes time. You have to wait until the response arrives and then read it. QNetworkAccessManager::post() just sends the post it does not wait for the response.

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

        H 1 Reply Last reply
        1
        • jsulmJ jsulm

          @Helson You cannot just read the response right after sending the post. The communication over network takes time. You have to wait until the response arrives and then read it. QNetworkAccessManager::post() just sends the post it does not wait for the response.

          H Offline
          H Offline
          Helson
          wrote on last edited by Helson
          #5

          @jsulm
          It's clear for me now.
          Can you show me a example of a response outside of a slot?
          I need it to check the response and decide the way the code
          If I use slot, I need put all my logic inside of a slot.

          Thank you and sorry for my bad english.

          --
          Something like

          reply = mpNetworkMgrSend->post(request, datatoSend);

          if(reply = "true"){
          ...
          } else{
          ...
          }

          1 Reply Last reply
          0
          • jsulmJ Offline
            jsulmJ Offline
            jsulm
            Lifetime Qt Champion
            wrote on last edited by
            #6

            You get a pointer to a QNetworkReply instance.
            Then you connect its readyRead() signal (or finished()) to a slot where you read the response data.
            Where is no need to do busy waiting for the reply.
            This is from Qt documentation (replace get() with post()):

            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()));
            connect(reply, SIGNAL(error(QNetworkReply::NetworkError)),
                    this, SLOT(slotError(QNetworkReply::NetworkError)));
            

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

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            0
            • jsulmJ Offline
              jsulmJ Offline
              jsulm
              Lifetime Qt Champion
              wrote on last edited by
              #7

              If you want to wait for the response for some reason you can call the QNetworkReply::isFinished() periodically. But take care to not to block the event loop, else you most probably will have an endless loop.

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

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              0
              • H Offline
                H Offline
                Helson
                wrote on last edited by Helson
                #8

                I'm trying but without success.

                QNetworkReply *reply = manager->get(request);
                connect(reply, SIGNAL(readyRead()), this, SLOT(slotReadyRead()));
                connect(reply, SIGNAL(error(QNetworkReply::NetworkError)), this, SLOT(slotError(QNetworkReply::NetworkError)))
                 
                while(!reply->isFinished()){                         
                    QString dataReply = (QString) reply->readAll();	
                }
                

                I can not get the reply out of the slot...

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                0
                • speqtrS Offline
                  speqtrS Offline
                  speqtr
                  wrote on last edited by
                  #9

                  Try this code:

                  QNetworkReply *reply = manager->get(request);
                  
                  QEventLoop loop;
                  connect(reply, SIGNAL(finished()), &loop, SLOT(quit()));
                  loop.exec();
                  
                  QByteArray data = reply->readAll();
                  QString dataReply(data);
                  

                  It should do the job.

                  H 1 Reply Last reply
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                  • speqtrS speqtr

                    Try this code:

                    QNetworkReply *reply = manager->get(request);
                    
                    QEventLoop loop;
                    connect(reply, SIGNAL(finished()), &loop, SLOT(quit()));
                    loop.exec();
                    
                    QByteArray data = reply->readAll();
                    QString dataReply(data);
                    

                    It should do the job.

                    H Offline
                    H Offline
                    Helson
                    wrote on last edited by Helson
                    #10

                    @speqtr

                    Hey!!
                    It's works like a charm!
                    Have a great day!
                    Thank you so much!!!

                    Problem solved finally!!!

                    1 Reply Last reply
                    0
                    • speqtrS Offline
                      speqtrS Offline
                      speqtr
                      wrote on last edited by
                      #11

                      You are welcome!
                      Have a nice day :)

                      HeerokNewbieH 1 Reply Last reply
                      3
                      • speqtrS speqtr

                        You are welcome!
                        Have a nice day :)

                        HeerokNewbieH Offline
                        HeerokNewbieH Offline
                        HeerokNewbie
                        wrote on last edited by
                        #12
                        This post is deleted!
                        1 Reply Last reply
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