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Exposing C++ values to QML issue

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  • T Offline
    T Offline
    Thanni123
    wrote on last edited by
    #3

    No, I just checked the value. dataObject is not empty and it will execute the setter methods.

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    • Christian EhrlicherC Offline
      Christian EhrlicherC Offline
      Christian Ehrlicher
      Lifetime Qt Champion
      wrote on last edited by
      #4

      Please properly initialize the members in the ctor and see if the 'strange' values disappear.

      Qt Online Installer direct download: https://download.qt.io/official_releases/online_installers/
      Visit the Qt Academy at https://academy.qt.io/catalog

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      • T Offline
        T Offline
        Thanni123
        wrote on last edited by
        #5

        I initialized all members but I still didn't get any values displayed on the qml side ...

        AlertMessage::AlertMessage(QObject *parent) :
            QObject(parent),
            m_messageType(""),
            m_sender(""),
            m_alertType(""),
            m_id(""),
            m_origin(""),
            m_dataSource(""),
            m_distanceToEvent(0),
            m_severity(0),
            m_azimuth(0),
            m_timeToEvent(0)
        {
        }
        
        Christian EhrlicherC 1 Reply Last reply
        0
        • fcarneyF Offline
          fcarneyF Offline
          fcarney
          wrote on last edited by
          #6

          QML, what QML? Please show the QML. Preferably a minimally compileable example.

          C++ is a perfectly valid school of magic.

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          • T Offline
            T Offline
            Thanni123
            wrote on last edited by
            #7

            Here is a snippet of my QML code

            import QtQuick 2.0
            import io.qt.alertmessage 1.0
            
            import "../BasicItems"
            import "../ModellingItems"
            
            import "../../WarningCalc.js" as WarningCalcer
            
            Rectangle
            {
                id: informationCellArea
            
                property int informationTextHeaderSize: 10
                property int informationTextSize: 17
                property int itemHeight: parent.height/4
                property int headerToTextMargin: 10
            
                property string senderString
                property string distanceString
                property string timeString
                property string descriptionString
                property string trafficSignString
                property int severityInt
            
                color: "transparent"
                radius: 10
            
                AlertMessage
                {
                    id: alertMessage
                }
            
                Item
                {
                    id: distanceArea
                    width: parent.width/2
                    height: itemHeight
                    anchors.left: parent.left
                    anchors.bottom: descriptionUseCaseArea.top
            
                    HMIText
                    {
                        id: distanceTextHeader
                        text: "Distance to event"
                        fontSize: informationTextHeaderSize
                        anchors.centerIn: parent
                    }
            
                    HMIText
                    {
                        id: distanceText
                        text:  alertMessage.distanceToEvent + " m"
                        fontSize: informationTextSize
                        useFontBold: true
                        anchors.top: distanceTextHeader.bottom
                        anchors.topMargin: headerToTextMargin
                        anchors.horizontalCenter: parent.horizontalCenter
            
                        onTextChanged: {
                            console.log("QML:" + distanceString);
                        }
                    }
                }
            }
            
            
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            • T Thanni123

              I initialized all members but I still didn't get any values displayed on the qml side ...

              AlertMessage::AlertMessage(QObject *parent) :
                  QObject(parent),
                  m_messageType(""),
                  m_sender(""),
                  m_alertType(""),
                  m_id(""),
                  m_origin(""),
                  m_dataSource(""),
                  m_distanceToEvent(0),
                  m_severity(0),
                  m_azimuth(0),
                  m_timeToEvent(0)
              {
              }
              
              Christian EhrlicherC Offline
              Christian EhrlicherC Offline
              Christian Ehrlicher
              Lifetime Qt Champion
              wrote on last edited by Christian Ehrlicher
              #8

              @Thanni123 said in Exposing C++ values to QML issue:

              get any values displayed on the qml side ...

              You don't see any double value or you don't see the strange values anymore? Please initialize one string to something other than an empty string.

              Qt Online Installer direct download: https://download.qt.io/official_releases/online_installers/
              Visit the Qt Academy at https://academy.qt.io/catalog

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              • fcarneyF Offline
                fcarneyF Offline
                fcarney
                wrote on last edited by
                #9

                What is in readDataFromJSONFormat and printout?
                So far I cannot see any real issues.

                C++ is a perfectly valid school of magic.

                T 1 Reply Last reply
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                • T Offline
                  T Offline
                  Thanni123
                  wrote on last edited by
                  #10

                  Well if I'm initializing the constructor with some default value, it display the value I've created. But if I try to set the values with the json file the value mentioned above appear or the value equals 0.

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                  • fcarneyF fcarney

                    What is in readDataFromJSONFormat and printout?
                    So far I cannot see any real issues.

                    T Offline
                    T Offline
                    Thanni123
                    wrote on last edited by
                    #11

                    @fcarney I've posted the method declaration above and the printout method is only a debug method to display if the values were set.

                    I think I did a mistake during initializing an object of my AlertMessage class but I didn't get my fault yet... It must be some stupid mistake I've done.

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                    • fcarneyF Offline
                      fcarneyF Offline
                      fcarney
                      wrote on last edited by
                      #12

                      @Thanni123 said in Exposing C++ values to QML issue:

                      But if I try to set the values with the json file the value mentioned above appear or the value equals 0.

                      The problem is in readDataFromJSONFormat and/or printout. If you want help you need to show what is in those. So far nothing you have posted shows any problems.

                      C++ is a perfectly valid school of magic.

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                      • T Offline
                        T Offline
                        Thanni123
                        wrote on last edited by
                        #13

                        Hey, I don't get your point exactly but here is the source code of your request for both methods including the output for the printout mehtod.

                        void AlertMessage::readDataFromJSONFormat(const QJsonObject &jsonObject)
                        {
                            if (jsonObject.count() <= 0)
                            {
                                qDebug() << "AlertMessage::Wrong JSON-Array.";
                                return;
                            }
                            cleanMessage();
                        
                            setMessageType(jsonObject["type"].toString());
                            setSender(jsonObject["sender"].toString());
                        
                            QJsonValue valueData = jsonObject.value(QString("data"));
                            QJsonObject dataObject = valueData.toObject();
                        
                            if (!dataObject.isEmpty())
                            {
                                setAlertType(dataObject["alert"].toString());
                                setID(dataObject["id"].toString());
                                setOrigin(dataObject["origin"].toString());
                                setDataSource(dataObject["data_source"].toString());
                                setDistanceToEvent(dataObject["distance_to_event"].toDouble());
                                setSeverity(dataObject["severity"].toDouble());
                                setAzimuth(dataObject["azimuth"].toDouble());
                                setTimeToEvent(dataObject["time_to_event"].toDouble());
                        
                                QJsonValue detailValue = dataObject.value(QString("detail"));
                                QJsonObject detailObject = detailValue.toObject();
                        
                                if (!detailObject.isEmpty())
                                {
                                     setDetailLevel(detailObject["level"].toInt());
                                }
                            }
                        }
                        
                        QString AlertMessage::printout()
                        {
                            QString print = "** AlertMessage begin**\n";
                            print += "MessageType       = " + QString("%1").arg(this->messageType()) + "\n";
                            print += "Sender            = " + QString("%1").arg(this->sender()) + "\n";
                            print += "AlertType         = " + QString("%1").arg(this->alertType()) + "\n";
                            print += "ID                = " + QString("%1").arg(this->id()) + "\n";
                            print += "Origin            = " + QString("%1").arg(this->origin()) + "\n";
                            print += "DataSource        = " + QString("%1").arg(this->dataSource()) + "\n";
                            print += "Distance_To_Event = " + QString("%1").arg(this->distanceToEvent()) + "\n";
                            print += "Severity          = " + QString("%1").arg(this->severity()) + "\n";
                            print += "Azimuth           = " + QString("%1").arg(this->azimuth()) + "\n";
                            print += "Time_To_Event     = " + QString("%1").arg(this->timeToEvent()) + "\n";
                            print += "DetailLevel       = " + QString("%1").arg(this->detailLevel()) + "\n";
                            print += "FCWAvailable      = " + QString("%1").arg(this->fcwReceived()) + "\n";
                            print += "RWWAvailable      = " + QString("%1").arg(this->rwwReceived()) + "\n";
                            print += "EEBLAvailable     = " + QString("%1").arg(this->eeblReceived()) + "\n";
                        
                            print += "** AlertMessage end **\n";
                        
                            return print;
                        }
                        

                        The output for my printout method:

                        QDateTime(2020-02-18 00:15:02.786 Mitteleuropäische Zeit Qt::LocalTime)
                        "** AlertMessage begin**\nMessageType       = ALERT\nSender            = \nAlertType         = FCW\nID                = \nOrigin            = Cohda_TA\nDataSource        = \nDistance_To_Event = 55.2\nSeverity          = 9\nAzimuth           = 25.5434\nTime_To_Event     = 20.3\nDetailLevel       = 0\nFCWAvailable      = 0\nRWWAvailable      = 0\nEEBLAvailable     = 0\n** AlertMessage end **\n"
                        

                        Hope this helps somehow :)

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                        • fcarneyF Offline
                          fcarneyF Offline
                          fcarney
                          wrote on last edited by
                          #14

                          I cannot see anything wrong in this code. All I can think is do a make clean, qmake, make project and see if this gets any better. I don't see any variables such as references exceeding their lifetime or anything. Sorry I cannot be more helpful. This should just work.

                          C++ is a perfectly valid school of magic.

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                          • T Offline
                            T Offline
                            Thanni123
                            wrote on last edited by
                            #15

                            I think I figured out the issue but I don't know how to solve it. It's relying on this call in the main.cpp.

                            main.cpp

                            qmlRegisterType<AlertMessage>("io.qt.alertmessage", 1, 0, "AlertMessage");
                            

                            This method uses the standard constructor of my AlertMessage class without the QJsonObject as a parameter. I need to define my custom constructor but I get stuck with some errors ...
                            If I don't use my custom constructor it will always initiliaze without any values set.

                            KroMignonK 1 Reply Last reply
                            0
                            • T Thanni123

                              I think I figured out the issue but I don't know how to solve it. It's relying on this call in the main.cpp.

                              main.cpp

                              qmlRegisterType<AlertMessage>("io.qt.alertmessage", 1, 0, "AlertMessage");
                              

                              This method uses the standard constructor of my AlertMessage class without the QJsonObject as a parameter. I need to define my custom constructor but I get stuck with some errors ...
                              If I don't use my custom constructor it will always initiliaze without any values set.

                              KroMignonK Offline
                              KroMignonK Offline
                              KroMignon
                              wrote on last edited by
                              #16

                              @Thanni123 said in Exposing C++ values to QML issue:

                              If I don't use my custom constructor it will always initiliaze without any values set.

                              This is exactly what @Christian-Ehrlicher has ask you to do: always initialize your member variables in constructor this is for all constructors.
                              So if you add a call to clearMessage() in your default constructor, you will probably solve your issue.

                              It is an old maxim of mine that when you have excluded the impossible, whatever remains, however improbable, must be the truth. (Sherlock Holmes)

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