QML slot looses context

Hello. I am developing an application with QML frontend and C++ backend – QML retrieves all data required by calling C++ functions on backend. From QML backend functions are accessible through special context property which is set like that: Backend backend; qmlContext->setContextProperty("backend", &backend); This is working nicely. However some backend functions are asynchrounous, so I would like to implement a promise-like solution – asynchronous function would return an intermediate promise object, which would emit signals when data is available. So my Promise class looks like this: class Promise: public QObject {     Q_OBJECT public:     explicit Promise(QObject* parent=0);   signals:     void finished(QVariant value);   private:     Q_DISABLE_COPY(Promise) ... };   ... qmlRegisterUncreatableType<Promise>("com.myapp", 1, 0, "Promise", "Promise can only be created from c++"); In Backend class asynchronous function is implemented like this: Q_INVOKABLE Promise* getData();   ..   Promise* Backend::getData() {     auto promise = new Promise(); ...     return promise; } In QML I am calling backend function, get promise object and connect a javascript function to its signal like this: Item {     id: root           Button {             id: button             ...               onClicked: {                 promise = backend.getData();                 promise.finished.connect(gotData);             }         }     }       property var promise: null       function gotData() {         console.log("gotData", root, button); // prints: gotData undefined undefined     } } The problem is, that QML function is called as intended when promise object emits ‘finished’ signal, however in that function no context variables are accessible. Am I missing something? Or is my approach totally wrong?