Cannot add model to QML

sierdzio

Your MainWindow is creating another QML engine which does not have "DataModel" set.

milan

@sierdzio . So, how can i fix it. Do I add DataModel in mainwindow.cpp?

sierdzio

QQmlApplicationEngine* engine = new QQmlApplicationEngine();

remove the engine since you're not using it anywhere. Or remove MainWindow if you are not using that. I don't know which is true in your case.

Extract the engine from your ui->quickWidget and add the DataModel there. If you are using QQuickWidget, you can use https://doc.qt.io/qt-5/qquickwidget.html#engine.

milan

@sierdzio .Thanks for your answer, it works. The initial value of gauge is set to 10. But the timer I have in my datamodel does not update the gauge value.

sierdzio

@milan said in Cannot add model to QML:

qDebug() << "Setting value:" << num;

Do you see this message printed?

milan

@sierdzio . I see that DataModel object gets destructed after it is constructed.

sierdzio

@milan said in Cannot add model to QML:

@sierdzio . I see that DataModel object gets destructed after it is constructed.

So make sure it lives long :-)

milan

@sierdzio. Yes I did that. Is qmlregistertype better way that setContextProperty I am using now? The C++ model should update the qml. Is it possible to use qmlregistertype in this context?

sierdzio

@milan said in Cannot add model to QML:

@sierdzio. Yes I did that. Is qmlregistertype better way that setContextProperty I am using now? The C++ model should update the qml

No it is not better, it server a different purpose. It makes the type recognizable (and creatable) in QML. Since you want to use a global data model (I think), then setting the context property is a better way for your use case. Just make sure DataModel object is not destroyed while your UI is alive. You can do it, for example, by declaring it as a member variable of MainWindow class, or by creating an object on heap and assigning MainWindow as parent.

milan

@sierdzio. Thanks a lot for your answer.