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);