SetContextProperty of a class that extends Object

javiyt

Hi,

I saw in this website how to make a class that extends Object to set an instance as a property.

http://doc.qt.nokia.com/4.7-snapshot/qtbinding.html#embedding-c-objects-into-qml-components

I did it as they say but I had some troubles and finally I had to separate to another file the class, but when I try to do this

@ApplicationData data;
view.rootContext()->setContextProperty("applicationData", &data);@

it gives this error:

'QVariant::QVariant(void*)' is private

I have tried to search the problem, and read about the classes priviledges but I don't know how to give an object as a property then. Thank you in advance.

Peppy

I think you have to write much more of code...
Maybe you forgot Q_OBJECT macro...

javiyt

Thank you for the fast answer.

I did just what the example was saying

@class ApplicationData : public QObject
{
Q_OBJECT
public:
Q_INVOKABLE QDateTime getCurrentDateTime() const {
return QDateTime::currentDateTime();
}
};
@

Well I had to write it in a separated file with the headers but it doesn't complaint about that, just gives back the error QVariant::QVariant(void*)'

javiyt

I discovered the problem but not the solution. If I delete the macro Q_OBJECT from the code it doesn't give any problem, but I can not call the functions inside from the QML. But when I include it in the code it gives the problem:

@ undefined reference to `vtable for ...' @

renato.filho

you need keep the Q_OBJECT macro (used on moc process), this is necessary to make your class a QObject.

try call the function with explicitly cast:
view.rootContext()->setContextProperty("applicationData", (QObject*)&data);

javiyt

Yes I included it, I wrote in the header Q_OBJECT as the example but it's all the time appearing this error.

@undefined reference to `vtable for ...'@

With the explicitly cast it doesn't give me the other error. It's a beginning, thanks!

renato.filho

Are you using qmake?
if yes, try put the Q_OBJECT macro, then re-run the qmake program, after that compile your program.

A moc file need be genereted and included on your src list. (qmake do this for you)

javiyt

I was doing it wrong, because what you said, I was doing it copying it directly. I discovered the way to add it correctly with Qtcreator.

Really helpfull, Thanks a lot!

lemma

Use QVariant::fromValue:
@view.rootContext()->setContextProperty("applicationData", QVariant::fromValue(data));@

http://qt-project.org/doc/qt-4.8/declarative-modelviews-stringlistmodel-main-cpp.html