如何使用qmlRegisterType在QML中指定c ++类型？

Question

I need use qmlRegisterType in c++ to define a commun type with QML. That's supposed to be simple but I have an error in the QML. Here's the c++.

QGuiApplication app(ai_argc, aipp_argv);

    qmlRegisterType<MiniModel>("miniModel", 1, 0, "MiniModel");//there it is !
    QQmlApplicationEngine engine;
    engine.addImportPath(QStringLiteral("..\\..\\..\\..\\Tools\\Qt\\5.12.0\\x64\\5.12.0\\msvc2017_64\\qml"));
    engine.load(QUrl(QStringLiteral("../../Inc/miniModel/miniModel.qml")));

    return app.exec();

and here is the QML

import QtQuick 2.5
import QtQuick.Window 2.5
import QtQuick.controls 2.5
import "..\\..\\x64\\Debug\\" miniModel 1.0 MiniModel//unknown component


ApplicationWindow {
    id: root
    width: 300
    height: 480
    visible: true
    property bool value: Minimodelqml.

    BackEnd {
        id: backend
    }

    TextField {
        text: backend.userName
        placeholderText: qsTr("User name")
        anchors.centerIn: parent

        onTextChanged: backend.userName = text
    }
}

I tried :

/*cpp*/qmlRegisterType<MiniModel>("miniModel", 1, 0, "MiniModel");
/*qml*/import miniModel 1.0 MiniModel //QML module not found

/*cpp*/qmlRegisterType<MiniModel>("anothertry.miniModel", 1, 0, "MiniModel");
/*cml*/import anothertry.miniModel 1.0//qml module not found

and some others... I'm new to QMl and don't know how to deal with it.

I'm not using a QtCreator project. It's a visual studio 2017 solution. Maybe the problem comes from there ?

edit : the code using the singleton works "fine"

Answer 1

Just import miniModel 1.0 in .qml should work

/*cpp*/qmlRegisterType<MiniModel>("miniModel", 1, 0, "MiniModel");
/*qml*/import miniModel 1.0 

Answer 2

Those are some of the frequent steps I do follow to expose C++ classes to the QML engine.

Let's start by declaring some constants:

struct package_manager {
    static constexpr auto package_name = "com.mohabouje.package";
    static constexpr auto package_version_major = 0;
    static constexpr auto package_version_minor = 1;
}

Then create your Qt Object, and expose the properties to the QML engine :

class MyObject : public QObject {
    Q_OBJECT
    Q_PROPERTY(double awesome READ awesome WRITE setAwesome NOTIFY awesomeChanged)
public:
    // ...
    double awesome();
    void setAwesome(double);
signals:
    void awesomeChanged(double);
};

In your main, then do:

int main(int argc, char* argv[]) {
    QApplication app(argc, argv);

    qmlRegisterType<MyObject>(package_manager::package_name,
        package_manager::package_version_major,
        package_manager::package_version_minor, "MyObject");

    QQmlApplicationEngine engine;
    engine.load(QUrl(QLatin1String("qrc:/main.qml")));
    if (engine.rootObjects().isEmpty())
        return -1;
    return app.exec();
}

And your main.qml becomes:

import com.mohabouje.pacakge 0.1

ApplicationWindow {
    id: root
    width: 300
    height: 480
    visible: true

    Component.onCompleted: {
        MyObject {
            awesome: 25
        }
    }

}

See this tutorial for more details.