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Storing data from QnetworkReply

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  • L LeeH

    @raven-worx

    No because If I do that, I will be able to read the data from the other function in that ba object but it will not be stored, so if i try to call that same function outside of the class it will be empty.

    raven-worxR Offline
    raven-worxR Offline
    raven-worx
    Moderators
    wrote on last edited by
    #13

    @LeeH
    but thats the point.
    readAll() only returns the data when it tells you that it has finished.
    Encapsulate your code into a helper class (each class has it's own QByteArray buffer).

    --- SUPPORT REQUESTS VIA CHAT WILL BE IGNORED ---
    If you have a question please use the forum so others can benefit from the solution in the future

    L 1 Reply Last reply
    1
    • raven-worxR raven-worx

      @LeeH
      but thats the point.
      readAll() only returns the data when it tells you that it has finished.
      Encapsulate your code into a helper class (each class has it's own QByteArray buffer).

      L Offline
      L Offline
      LeeH
      wrote on last edited by LeeH
      #14

      @raven-worx said in Storing data from QnetworkReply:

      Encapsulate your code into a helper class (each class has it's own QByteArray buffer).

      So would I have to set objects from other places directly to the reply data?

      mrjjM 1 Reply Last reply
      0
      • L LeeH

        @raven-worx said in Storing data from QnetworkReply:

        Encapsulate your code into a helper class (each class has it's own QByteArray buffer).

        So would I have to set objects from other places directly to the reply data?

        mrjjM Offline
        mrjjM Offline
        mrjj
        Lifetime Qt Champion
        wrote on last edited by mrjj
        #15

        @LeeH
        Have a look at this sample
        http://www.bogotobogo.com/Qt/Qt5_Downloading_Files_QNetworkAccessManager_QNetworkRequest.php
        It uses a small helper class
        class Downloader : public QObject
        to manage the data it downloads. It responds to the finished signal.
        Here it stores to file but you can as well store in ByteArray or whatever is needed.

        Also its important to understand that you should NOT call the ReadData function yourself.
        Your function will be called when data is ready. Its an asynchronous API.

        L 2 Replies Last reply
        0
        • mrjjM mrjj

          @LeeH
          Have a look at this sample
          http://www.bogotobogo.com/Qt/Qt5_Downloading_Files_QNetworkAccessManager_QNetworkRequest.php
          It uses a small helper class
          class Downloader : public QObject
          to manage the data it downloads. It responds to the finished signal.
          Here it stores to file but you can as well store in ByteArray or whatever is needed.

          Also its important to understand that you should NOT call the ReadData function yourself.
          Your function will be called when data is ready. Its an asynchronous API.

          L Offline
          L Offline
          LeeH
          wrote on last edited by
          #16

          @mrjj

          Ok thanks for that, I will check it out.

          1 Reply Last reply
          0
          • mrjjM mrjj

            @LeeH
            Have a look at this sample
            http://www.bogotobogo.com/Qt/Qt5_Downloading_Files_QNetworkAccessManager_QNetworkRequest.php
            It uses a small helper class
            class Downloader : public QObject
            to manage the data it downloads. It responds to the finished signal.
            Here it stores to file but you can as well store in ByteArray or whatever is needed.

            Also its important to understand that you should NOT call the ReadData function yourself.
            Your function will be called when data is ready. Its an asynchronous API.

            L Offline
            L Offline
            LeeH
            wrote on last edited by LeeH
            #17

            @mrjj

            Have a look at this sample
            http://www.bogotobogo.com/Qt/Qt5_Downloading_Files_QNetworkAccessManager_QNetworkRequest.php
            It uses a small helper class
            class Downloader : public QObject
            to manage the data it downloads. It responds to the finished signal.
            Here it stores to file but you can as well store in ByteArray or whatever is needed.

            I already have a class doing this job - as I said in the begining I can already save my reply data to file that can be read/used from anywhere in one signal slot connection, I just want to do the same thing without using a file so it can be read/used from anywhere in a single connection. If my class data object that has been assigned (or appended to) the value of reply's byte array is always empty when called, say from outside of the class (after download), meaning I have to re-download everytime I need the same data, then the reply data is not stored to my object is it?

            mrjjM 1 Reply Last reply
            0
            • L LeeH

              @mrjj

              Have a look at this sample
              http://www.bogotobogo.com/Qt/Qt5_Downloading_Files_QNetworkAccessManager_QNetworkRequest.php
              It uses a small helper class
              class Downloader : public QObject
              to manage the data it downloads. It responds to the finished signal.
              Here it stores to file but you can as well store in ByteArray or whatever is needed.

              I already have a class doing this job - as I said in the begining I can already save my reply data to file that can be read/used from anywhere in one signal slot connection, I just want to do the same thing without using a file so it can be read/used from anywhere in a single connection. If my class data object that has been assigned (or appended to) the value of reply's byte array is always empty when called, say from outside of the class (after download), meaning I have to re-download everytime I need the same data, then the reply data is not stored to my object is it?

              mrjjM Offline
              mrjjM Offline
              mrjj
              Lifetime Qt Champion
              wrote on last edited by
              #18

              @LeeH said in Storing data from QnetworkReply:
              Hi
              If you keep the instance of class Downloader around,
              there is no reason you cannot keep the data for later.
              Say if you append to a QByteArray variable defined as
              class member in Downloader

              Can you please show the actual code how you use your helper class and how you later
              try to access the data?

              L 1 Reply Last reply
              0
              • mrjjM mrjj

                @LeeH said in Storing data from QnetworkReply:
                Hi
                If you keep the instance of class Downloader around,
                there is no reason you cannot keep the data for later.
                Say if you append to a QByteArray variable defined as
                class member in Downloader

                Can you please show the actual code how you use your helper class and how you later
                try to access the data?

                L Offline
                L Offline
                LeeH
                wrote on last edited by
                #19

                @mrjj said in Storing data from QnetworkReply:

                Can you please show the actual code how you use your helper class and how you later
                try to access the data?

                Certainly.

                header:

                class data : public QObject{
                
                    Q_OBJECT
                
                public:
                    data();
                    void download();
                    QByteArray get();
                
                public slots:
                
                    void output(QNetworkReply* rep);
                
                private:
                    QNetworkAccessManager* _qnam;
                    QByteArray _ba;
                
                };
                

                source:

                data::data(){}
                
                void data::download(){
                
                    _qnam = new QNetworkAccessManager(this);
                    _qnam->get(QNetworkRequest(QUrl("http://www.google.com")));
                    QObject::connect(_qnam, SIGNAL(finished(QNetworkReply*)), this, SLOT(output(QNetworkReply*)));
                }
                
                void data::output(QNetworkReply* rep){
                
                        if(!rep->error()){
                
                           _ba.append(rep->readAll());
                
                        }
                        rep->deleteLater();
                    }
                
                QByteArray data::get(){
                    qDebug() << _ba;
                }
                

                main:

                 data obj;
                 obj.download();
                 obj.get();
                
                jsulmJ 1 Reply Last reply
                0
                • L LeeH

                  @mrjj said in Storing data from QnetworkReply:

                  Can you please show the actual code how you use your helper class and how you later
                  try to access the data?

                  Certainly.

                  header:

                  class data : public QObject{
                  
                      Q_OBJECT
                  
                  public:
                      data();
                      void download();
                      QByteArray get();
                  
                  public slots:
                  
                      void output(QNetworkReply* rep);
                  
                  private:
                      QNetworkAccessManager* _qnam;
                      QByteArray _ba;
                  
                  };
                  

                  source:

                  data::data(){}
                  
                  void data::download(){
                  
                      _qnam = new QNetworkAccessManager(this);
                      _qnam->get(QNetworkRequest(QUrl("http://www.google.com")));
                      QObject::connect(_qnam, SIGNAL(finished(QNetworkReply*)), this, SLOT(output(QNetworkReply*)));
                  }
                  
                  void data::output(QNetworkReply* rep){
                  
                          if(!rep->error()){
                  
                             _ba.append(rep->readAll());
                  
                          }
                          rep->deleteLater();
                      }
                  
                  QByteArray data::get(){
                      qDebug() << _ba;
                  }
                  

                  main:

                   data obj;
                   obj.download();
                   obj.get();
                  
                  jsulmJ Online
                  jsulmJ Online
                  jsulm
                  Lifetime Qt Champion
                  wrote on last edited by
                  #20

                  @LeeH said in Storing data from QnetworkReply:

                  QNetworkReply

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

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

                  L 1 Reply Last reply
                  2
                  • jsulmJ jsulm

                    @LeeH said in Storing data from QnetworkReply:

                    QNetworkReply

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

                    L Offline
                    L Offline
                    LeeH
                    wrote on last edited by LeeH
                    #21

                    @jsulm said in Storing data from QnetworkReply:

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

                    Hi

                    Do you mean another connection, something like this:

                    void data::download(){
                    
                       _qnam->get(QNetworkRequest(QUrl("http://www.google.com")));
                       QObject::connect(_qnam, SIGNAL(finished(QNetworkReply*)), this, SLOT(output(QNetworkReply*)));
                       QObject::connect(QIODevice, SIGNAL(readyRead()), this, SLOT(output(QNetworkReply*)));
                    
                    }
                    

                    I know the QIODevice usage here is wrong, but just trying to get an idea

                    thanks

                    jsulmJ 1 Reply Last reply
                    0
                    • L LeeH

                      @jsulm said in Storing data from QnetworkReply:

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

                      Hi

                      Do you mean another connection, something like this:

                      void data::download(){
                      
                         _qnam->get(QNetworkRequest(QUrl("http://www.google.com")));
                         QObject::connect(_qnam, SIGNAL(finished(QNetworkReply*)), this, SLOT(output(QNetworkReply*)));
                         QObject::connect(QIODevice, SIGNAL(readyRead()), this, SLOT(output(QNetworkReply*)));
                      
                      }
                      

                      I know the QIODevice usage here is wrong, but just trying to get an idea

                      thanks

                      jsulmJ Online
                      jsulmJ Online
                      jsulm
                      Lifetime Qt Champion
                      wrote on last edited by
                      #22

                      @LeeH No need for two connections, the one for readyRead() is enough

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

                      L 1 Reply Last reply
                      1
                      • jsulmJ jsulm

                        @LeeH No need for two connections, the one for readyRead() is enough

                        L Offline
                        L Offline
                        LeeH
                        wrote on last edited by
                        #23

                        @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

                        m.sueM jsulmJ 2 Replies Last reply
                        0
                        • 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

                          m.sueM Offline
                          m.sueM Offline
                          m.sue
                          wrote on last edited by
                          #24

                          Hi @LeeH

                          You need the QIODevice type object not the class name there.

                          -Michael.

                          L 1 Reply Last reply
                          0
                          • m.sueM m.sue

                            Hi @LeeH

                            You need the QIODevice type object not the class name there.

                            -Michael.

                            L Offline
                            L Offline
                            LeeH
                            wrote on last edited by
                            #25

                            @m.sue

                            Hi,

                            QIODevice is an abstract class.

                            m.sueM 1 Reply Last reply
                            0
                            • L LeeH

                              @m.sue

                              Hi,

                              QIODevice is an abstract class.

                              m.sueM Offline
                              m.sueM Offline
                              m.sue
                              wrote on last edited by
                              #26

                              Hi @LeeH

                              then the object of the derived class that you use.

                              -Michael.

                              L 1 Reply Last reply
                              0
                              • m.sueM m.sue

                                Hi @LeeH

                                then the object of the derived class that you use.

                                -Michael.

                                L Offline
                                L Offline
                                LeeH
                                wrote on last edited by
                                #27

                                @m.sue said in Storing data from QnetworkReply:

                                then the object of the derived class that you use.

                                I modified my code to use readRead() from QNetworkReply object and it still doesn't work:

                                ...
                                void data::download(){
                                
                                _rep = _qnam->get(QNetworkRequest(QUrl("http://www.google.com")));
                                QObject::connect(_rep, SIGNAL(readyRead()), this, SLOT(output()));
                                
                                }
                                
                                void data::output(){
                                
                                    if(!_rep->error()){
                                
                                       _ba.append(_rep->readAll());
                                
                                    }
                                    else{
                                        qDebug() << _rep->error();
                                    }
                                    _rep->deleteLater();
                                }
                                
                                m.sueM 1 Reply Last reply
                                0
                                • L LeeH

                                  @m.sue said in Storing data from QnetworkReply:

                                  then the object of the derived class that you use.

                                  I modified my code to use readRead() from QNetworkReply object and it still doesn't work:

                                  ...
                                  void data::download(){
                                  
                                  _rep = _qnam->get(QNetworkRequest(QUrl("http://www.google.com")));
                                  QObject::connect(_rep, SIGNAL(readyRead()), this, SLOT(output()));
                                  
                                  }
                                  
                                  void data::output(){
                                  
                                      if(!_rep->error()){
                                  
                                         _ba.append(_rep->readAll());
                                  
                                      }
                                      else{
                                          qDebug() << _rep->error();
                                      }
                                      _rep->deleteLater();
                                  }
                                  
                                  m.sueM Offline
                                  m.sueM Offline
                                  m.sue
                                  wrote on last edited by
                                  #28

                                  Hi @LeeH

                                  I would write: connect(_rep, SIGNAL(readyRead()), SLOT(output())); But this should not be essential.

                                  So maybe output() is not a slot.

                                  -Michael.

                                  L 1 Reply Last reply
                                  0
                                  • mrjjM Offline
                                    mrjjM Offline
                                    mrjj
                                    Lifetime Qt Champion
                                    wrote on last edited by
                                    #29

                                    @LeeH said in Storing data from QnetworkReply:

                                    qDebug() << _rep->error();

                                    Is line ever activated ?
                                    is _ba.append called ?

                                    L 1 Reply Last reply
                                    0
                                    • m.sueM m.sue

                                      Hi @LeeH

                                      I would write: connect(_rep, SIGNAL(readyRead()), SLOT(output())); But this should not be essential.

                                      So maybe output() is not a slot.

                                      -Michael.

                                      L Offline
                                      L Offline
                                      LeeH
                                      wrote on last edited by
                                      #30

                                      @m.sue said in Storing data from QnetworkReply:

                                      So maybe output() is not a slot.

                                      Hi it's always been a public slot... and i do get server reply data

                                      1 Reply Last reply
                                      0
                                      • mrjjM mrjj

                                        @LeeH said in Storing data from QnetworkReply:

                                        qDebug() << _rep->error();

                                        Is line ever activated ?
                                        is _ba.append called ?

                                        L Offline
                                        L Offline
                                        LeeH
                                        wrote on last edited by
                                        #31

                                        @mrjj said in Storing data from QnetworkReply:

                                        Is line ever activated ?
                                        is _ba.append called ?

                                        Hi, there are no errors from server, and I always get reply.
                                        I call _ba from main() using data::get()

                                        mrjjM 1 Reply Last reply
                                        0
                                        • L LeeH

                                          @mrjj said in Storing data from QnetworkReply:

                                          Is line ever activated ?
                                          is _ba.append called ?

                                          Hi, there are no errors from server, and I always get reply.
                                          I call _ba from main() using data::get()

                                          mrjjM Offline
                                          mrjjM Offline
                                          mrjj
                                          Lifetime Qt Champion
                                          wrote on last edited by
                                          #32

                                          @LeeH
                                          but is data appended?

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

                                          have you tried with a breakpoint ?
                                          is data::output() called?

                                          L 1 Reply Last reply
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