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Json sending and receiving and finding keys inside json

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  • K Kris Revi

    so here im sending a response when "001" (Request Info) is sent to the ESP32

        DynamicJsonDocument doc2(256);                       // Init Dynamic Json Document
        String jsonData;                                     // Make Json Variable To Store Outgoing Json
    
        if (doc["001"] && doc["001"] == "yes") {             // Request Info
    
            Serial.println("Requested Info");
    
            doc2["300"] = DeviceType;                        // Device Type
            doc2["301"] = DeviceName;                        // Device Name
            doc2["303"] = DeviceLEDType;                     // Device LED Type
    
            serializeJson(doc2, jsonData);                   // Serialize Json
            webSocket.sendTXT(num, jsonData);                // Send Json Data Via Socket
            Serial.println(jsonData);
        }
    

    Printing out jsonData it looks like this

    {"300":"ESP32","301":"Matrix Display","303":"Matrix"}
    

    perfect! now on the other end

    void MainWindow::onRequestedInfoReceived(QString message)
    {
        qDebug() << "[SOCKET][INFO] Requested Info : " << message;
    }
    

    Printing out message looks this

    [SOCKET][INFO] Requested Info :  "{\"300\":\"ESP32\",\"301\":\"Matrix Display\",\"303\":\"Matrix\"}"
    

    why the \ because of QString?

    JonBJ Offline
    JonBJ Offline
    JonB
    wrote on last edited by
    #2

    @Kris-Revi
    What is your question? Yes, qDebug() displaying a string shows embedded double-quote characters as \".

    1 Reply Last reply
    0
    • K Offline
      K Offline
      Kris Revi
      wrote on last edited by
      #3

      my question is does this affect when i try to

          QJsonDocument doc = QJsonDocument::fromJson(message);
          QJsonValue test = doc.object().value("001");
      

      also this gives me no viable conversion from 'QString' to 'const QByteArray'

      JonBJ 1 Reply Last reply
      0
      • K Kris Revi

        my question is does this affect when i try to

            QJsonDocument doc = QJsonDocument::fromJson(message);
            QJsonValue test = doc.object().value("001");
        

        also this gives me no viable conversion from 'QString' to 'const QByteArray'

        JonBJ Offline
        JonBJ Offline
        JonB
        wrote on last edited by
        #4

        @Kris-Revi
        [static]QJsonDocument QJsonDocument::fromJson(const QByteArray &json, QJsonParseError *error = nullptr) accepts input as a QByteArray:

        Parses json as a UTF-8 encoded JSON document,

        I don't know where you got your void MainWindow::onRequestedInfoReceived(QString message) with QString parameter from, data is sent around (serial ports, sockets) as bytes, so that's what it should be. If necessary, don't forget there is QByteArray QString::toUtf8() const.

        1 Reply Last reply
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        • K Offline
          K Offline
          Kris Revi
          wrote on last edited by
          #5

          i can only set QString void MainWindow::onRequestedInfoReceived(QString message) it wont allow me to set QByteArray or bytes or anything realy :S

          JonBJ 1 Reply Last reply
          0
          • K Kris Revi

            i can only set QString void MainWindow::onRequestedInfoReceived(QString message) it wont allow me to set QByteArray or bytes or anything realy :S

            JonBJ Offline
            JonBJ Offline
            JonB
            wrote on last edited by
            #6

            @Kris-Revi
            I assume that method is a slot, and since you don't show the signal connection I cannot comment.

            So did you try the QByteArray QString::toUtf8() const?

            1 Reply Last reply
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            • K Offline
              K Offline
              Kris Revi
              wrote on last edited by
              #7

              @JonB
              this is the Q_SIGNAL

              void onRequestedInfoReceived(QString message);
              

              this is the Q_SLOT

              void onRequestedInfoReceived(QString message);
              
              JonBJ 1 Reply Last reply
              0
              • K Kris Revi

                @JonB
                this is the Q_SIGNAL

                void onRequestedInfoReceived(QString message);
                

                this is the Q_SLOT

                void onRequestedInfoReceived(QString message);
                
                JonBJ Offline
                JonBJ Offline
                JonB
                wrote on last edited by
                #8

                @Kris-Revi
                Fine.
                And for the third time of suggesting/asking: how are you finding using QByteArray QString::toUtf8() const on it then works for making your QString message acceptable to QJsonDocument::fromJson() with no error? I'm not going to repeat this further.

                K 2 Replies Last reply
                0
                • JonBJ JonB

                  @Kris-Revi
                  Fine.
                  And for the third time of suggesting/asking: how are you finding using QByteArray QString::toUtf8() const on it then works for making your QString message acceptable to QJsonDocument::fromJson() with no error? I'm not going to repeat this further.

                  K Offline
                  K Offline
                  Kris Revi
                  wrote on last edited by
                  #9

                  @JonB wait... QByteArray QString::toUtf8() const ? :S

                  1 Reply Last reply
                  0
                  • JonBJ JonB

                    @Kris-Revi
                    Fine.
                    And for the third time of suggesting/asking: how are you finding using QByteArray QString::toUtf8() const on it then works for making your QString message acceptable to QJsonDocument::fromJson() with no error? I'm not going to repeat this further.

                    K Offline
                    K Offline
                    Kris Revi
                    wrote on last edited by
                    #10

                    @JonB did this

                    void MainWindow::onRequestedInfoReceived(QString message)
                    {
                        //qDebug() << "[SOCKET][INFO] Requested Info : " << message;
                    
                        QByteArray messageArray = message.toUtf8();
                    
                        QJsonDocument doc = QJsonDocument::fromJson(messageArray);
                    
                        QJsonValue test = doc.object().value("001");
                    
                        qDebug() << "Board Type : " << test;
                    }
                    

                    got

                    Board Type :  QJsonValue(undefined)
                    
                    JonBJ 1 Reply Last reply
                    0
                    • fcarneyF Offline
                      fcarneyF Offline
                      fcarney
                      wrote on last edited by
                      #11

                      What does

                      qDebug().noquote() << message; 
                      

                      do?
                      It might remove the quoting altogether and make it more readable.

                      C++ is a perfectly valid school of magic.

                      1 Reply Last reply
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                      • K Kris Revi

                        @JonB did this

                        void MainWindow::onRequestedInfoReceived(QString message)
                        {
                            //qDebug() << "[SOCKET][INFO] Requested Info : " << message;
                        
                            QByteArray messageArray = message.toUtf8();
                        
                            QJsonDocument doc = QJsonDocument::fromJson(messageArray);
                        
                            QJsonValue test = doc.object().value("001");
                        
                            qDebug() << "Board Type : " << test;
                        }
                        

                        got

                        Board Type :  QJsonValue(undefined)
                        
                        JonBJ Offline
                        JonBJ Offline
                        JonB
                        wrote on last edited by JonB
                        #12

                        @Kris-Revi
                        Print out things like QJsonDocument::isNull(), QJsonDocument::isObject(), QJsonDocument::object(). What about looking at doc.object().keys() to see what is actually in there?

                        1 Reply Last reply
                        0
                        • K Offline
                          K Offline
                          Kris Revi
                          wrote on last edited by
                          #13

                          the printing out part is realy not an issue :) i just noticed that there was added \ in the print out and i thought that that would affect the way im searching for keys!

                          JonBJ 1 Reply Last reply
                          0
                          • SGaistS Offline
                            SGaistS Offline
                            SGaist
                            Lifetime Qt Champion
                            wrote on last edited by
                            #14

                            Hi,

                            Side questions:

                            • Where are you getting that JSON data from ?
                            • Do you receive it directly a QString ?
                            • If not, why not change the slot signature to use a QByteArray, or even better use a const reference on a QByteArray.

                            Interested in AI ? www.idiap.ch
                            Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

                            K 1 Reply Last reply
                            0
                            • SGaistS SGaist

                              Hi,

                              Side questions:

                              • Where are you getting that JSON data from ?
                              • Do you receive it directly a QString ?
                              • If not, why not change the slot signature to use a QByteArray, or even better use a const reference on a QByteArray.
                              K Offline
                              K Offline
                              Kris Revi
                              wrote on last edited by
                              #15

                              @SGaist scroll to the top and you will see where i get that json from and the answer to the QString question :)

                              1 Reply Last reply
                              0
                              • K Kris Revi

                                the printing out part is realy not an issue :) i just noticed that there was added \ in the print out and i thought that that would affect the way im searching for keys!

                                JonBJ Offline
                                JonBJ Offline
                                JonB
                                wrote on last edited by JonB
                                #16

                                @Kris-Revi said in Json sending and receiving and finding keys inside json:

                                the printing out part is realy not an issue :)

                                Well, yes/no, but You are wanting to get back the doc2["300"] = DeviceType/"300":"ESP32" you put in, and you say you're not succedding with doc.object().value("001"), so you need to look at what the document you have parsed back has come out like.

                                EDIT Hang on, aren't you looking for the wrong thing? When you showed the string received earlier it was:

                                [SOCKET][INFO] Requested Info :  "{\"300\":\"ESP32\",\"301\":\"Matrix Display\",\"303\":\"Matrix\"}"
                                

                                So why are you now asking for doc.object().value("001"); ? QJsonValue(undefined) looks about the right for that!

                                K 1 Reply Last reply
                                0
                                • B Offline
                                  B Offline
                                  Bonnie
                                  wrote on last edited by
                                  #17

                                  I'm guessing that OP get his data from QWebSocket.
                                  So if he connects QWebSocket::textMessageReceived signal, then he'll get directly a QString.

                                  1 Reply Last reply
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                                  • JonBJ JonB

                                    @Kris-Revi said in Json sending and receiving and finding keys inside json:

                                    the printing out part is realy not an issue :)

                                    Well, yes/no, but You are wanting to get back the doc2["300"] = DeviceType/"300":"ESP32" you put in, and you say you're not succedding with doc.object().value("001"), so you need to look at what the document you have parsed back has come out like.

                                    EDIT Hang on, aren't you looking for the wrong thing? When you showed the string received earlier it was:

                                    [SOCKET][INFO] Requested Info :  "{\"300\":\"ESP32\",\"301\":\"Matrix Display\",\"303\":\"Matrix\"}"
                                    

                                    So why are you now asking for doc.object().value("001"); ? QJsonValue(undefined) looks about the right for that!

                                    K Offline
                                    K Offline
                                    Kris Revi
                                    wrote on last edited by
                                    #18

                                    @JonB you are actualy correct! xD im looking for "303" NOT the "001" that is "Request Info"

                                    1 Reply Last reply
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