How to use qmlRegisterUncreableType

[serkan_tr]

Not many resources on how to use qmlRegisterUncreableType. i tried to use it but i get errors

#include <QGuiApplication>
#include <QQmlApplicationEngine>
#include <QQmlContext>
#include "comm.h"

/*
 *  qmlRegisterType
 *  qmlRegisterUncreatableType
*/
int main(int argc, char *argv[])
{
    comm* com_port = new comm();
    com_port->settx_data(10);
    com_port->setname_classs("serkan");
    QGuiApplication app(argc, argv);
    QQmlApplicationEngine engine;
    const QUrl url(QStringLiteral("qrc:/main.qml"));
    QObject::connect(&engine, &QQmlApplicationEngine::objectCreated,
                     &app, [url](QObject *obj, const QUrl &objUrl) {
        if (!obj && url == objUrl)
            QCoreApplication::exit(-1);
    }, Qt::QueuedConnection);

    qmlRegisterUncreatableType<comm>("com.example", 1, 0, "comm","MyCustomClass should not be created from QML.");

//    engine.rootContext()->setContextProperty("myObject", com_port);
    engine.load(url);
    app.exec();
    delete com_port;
    return 0 ;
}

import QtQuick 2.15
import QtQuick.Window 2.15
import com.example 1.0

Window {
    width: 640
    height: 480
    visible: true
    title: qsTr("Hello World")
    Rectangle{
        height: 100
        width:  100
        anchors.centerIn: parent
        color:"black"
        Text {
            id: aaa
            text: comm.name_classs
            anchors.centerIn: parent
            color:"green"
        }
    }
}

#include "comm.h"

comm::comm(): value(0), name("")
{
    qDebug() << "Constructor Worked...";

}
comm::~comm(){
    qDebug() << "Destructor Worked...";
}

QString comm::getName()
{
    qDebug() << name;
    return name;

}

void comm::setName(QString newName)
{
    if(name == newName){
        name = newName;
    }
}

int comm::tx_data() const
{
    return m_tx_data;
}

void comm::settx_data(int newTx_data)
{
    if (m_tx_data == newTx_data)
        return;
    m_tx_data = newTx_data;
    emit tx_dataChanged();
}

QString comm::name_classs() const
{
    return m_name_classs;
}

void comm::setname_classs(const QString &newName_classs)
{
    if (m_name_classs == newName_classs)
        return;
    m_name_classs = newName_classs;
    emit name_classsChanged();
}

#ifndef COMM_H
#define COMM_H

#include <QObject>
#include <QDebug>

class comm: public QObject
{
    Q_OBJECT
    Q_PROPERTY(int tx_data READ tx_data WRITE setTx_data NOTIFY tx_dataChanged)
    Q_PROPERTY(QString name_classs READ name_classs WRITE setName_classs NOTIFY name_classsChanged)
public:
    comm();
    ~comm();
    QString getName();
    void setName(QString newName);

    int tx_data() const;
    void settx_data(int newTx_data);

    QString name_classs() const;
    void setname_classs(const QString &newName_classs);

signals:
    void tx_dataChanged();

    void name_classsChanged();

private:
    QString name;
    int value;
    int m_tx_data;
    QString m_name_classs;
};

#endif // COMM_H

[sierdzio]

You have to register before you construct the QML engine QQmlApplicationEngine engine;.

Also, your comm constructor should call parent class constructor:

comm::comm(): QObject(nullptr), value(0), name("")

Lastly, you try to use comm in QML as if it was an object, but it is uncreatable. There is no instance, so you can't call name_classs property. There are 2 reasons to use qmlRegisterUncreableType:

• you need to use enum values declared in C++ on QML side
• your QML code needs to access instances of registered type but should not be allowed to construct them

[serkan_tr]

@sierdzio
Thank you