QML doesn't recognise enums registered in a separate namespace - qt

Question

I have registered an enum in a separate namespace using Q_ENUM_NS. Then I would like to communicate between C++ and QML using signals. In particular, I have a class sending emitting signals where the signature of the signal contains an enum from my namespace. However, QML doesn't seem to recognise the enum value (which is always "undefined").
Here is an example that showcases the problem:
// main.cpp
#include <QGuiApplication>
#include <QQmlApplicationEngine>
#include <QObject>
#include <QTimer>
namespace Enums {
Q_NAMESPACE
enum class MyEnum { First, Second, Third };
Q_ENUM_NS(MyEnum)
}
class TestObject : public QObject {
Q_OBJECT
public:
explicit TestObject() {
timer.setInterval(1000);
QObject::connect(&timer, &QTimer::timeout, this, [&](){
auto myEnum = Enums::MyEnum::First;
qDebug () << "CPP" << myEnum;
emit testSignal(myEnum);
});
timer.start();
}
signals:
void testSignal(Enums::MyEnum myEnum);
private:
QTimer timer;
};
#include "main.moc"
int main(int argc, char *argv[])
{
QGuiApplication app(argc, argv);
QQmlApplicationEngine engine;
qmlRegisterUncreatableMetaObject(Enums::staticMetaObject, "Enums", 1, 0, "Enums", "Error: enums can't be created");
qmlRegisterType<TestObject>("TestObject", 1, 0, "TestObject");
const QUrl url(QStringLiteral("qrc:/main.qml"));
engine.load(url);
return app.exec();
}
// main.qml
import QtQuick 2.15
import QtQuick.Window 2.15
import Enums 1.0
import TestObject 1.0
Window {
width: 640
height: 480
visible: true
title: qsTr("Hello World")
TestObject{
id: object
onTestSignal: (myEnum) => { console.debug(myEnum) }
}
}
I would expect QML to recognise the value of the enum and print "Enums.First"

Answer 1

you need to register meta type before registering meta object:
qRegisterMetaType<Enums>("Enums");
Then import it like:
import Enums 1.0