QJSEngine, how to expose C++ enum to a JavaScript?

[Alhasni]

I managed to expose an (uninstantiable) class to JavaScript using qmlRegisterType as follows:

class MyClass : public QObject {
	Q_OBJECT
public:
	MyClass ()  : _name("MyClass") { }

	Q_INVOKABLE void setName(QString name) { _name = name; }

	Q_INVOKABLE QString getName() { return _name; }

	enum MyEnum { Entry1, Entry2 };

private:
	QString _name;
};

// registered using qmlRegisterType<MyClass>()

But I cannot access MyEnum. Looking online there are only examples on how to do it with QML using import.

[dheerendra]

Did you try using Q_ENUM ?

[Alhasni]

@dheerendra I added Q_ENUM(MyEnum) after the enum declaration but that didn't work.

When I try to access it using m.Entry1 where m is an instance of MyClass I instantiate from a global object, I just get an "undefined" value.

Note that I also cannot access it using MyClass.Entry1, I get the error:
Uncaught exception at line 5: ReferenceError: MyClass is not defined

[dheerendra]

Can you register your class like this ?

qmlRegisterType< MyClass >("MyApp",1,0,"MyEnums");

Now accès it as MyEnums.Entry1

[Alhasni]

@dheerendra

Still doesn't work unfortunately.

class MyClass : public QObject {
	Q_OBJECT
public:
	MyClass() : _name("MyClass") { }

	Q_INVOKABLE void setName(QString name) { _name = name; }

	Q_INVOKABLE QString getName() { return _name; }

	enum MyEnum { Entry1, Entry2 };
	Q_ENUM(MyEnum)

private:
	QString _name;
};

// registered using qmlRegisterType<MyClass>("MyApp", 1, 0, "MyEnums");

Evaluate:

let c = controller.createClass();
c.getName();
MyEnums.Entry1

Error: Uncaught exception at line 4: ReferenceError: MyEnums is not defined

With QML, the examples would also import the registered type when running the script, but that doesnt work with QJSEngine...

[dheerendra]

Where did you include the qmlRegisterType ? Did you make the import statements in qml ?

[Alhasni]

I don't understand the question. I am using QJSEngine, not QQMLEngine.

I use qmlRegisterType like this:

QJSEngine _jsEngine;

QJSValue objectValue = _jsEngine.newQObject(_controller);
_jsEngine.globalObject().setProperty("controller", objectValue);

_jsEngine.installExtensions(QJSEngine::Extension::ConsoleExtension);

qmlRegisterType<MyClass>("MyApp", 1, 0, "MyEnums");

QJSValue result = _jsEngine.evaluate(script->toPlainText());

[Gojir4]

Hi @Alhasni,

According to https://doc.qt.io/qt-5/qjsengine.html#qobject-integration I guess you need to use QJSEngine::newQMetaObject():

QJSValue enumObjectValue = _jsEngine.newQMetaObject(_controller->metaObject());
_jsEngine.globalObject().setProperty("controller", enumObjectValue);