QT: Problem, How do I return my own QObject derived custom class as “QVariant”?

Question

Implementing a derived “QAbstractListModel::data” method.

Q_DECLARE_METATYPE(myType); doesn’t even compile…. returning my custom object results in a compilation error.

How can this be done?

Answer 1

QVariant::fromValue<QObject *>(object);

replace QObject with your own type, but use Q_DECLARE_METATYPE on it. Keep in mind what you are declaring: the MyType or MyType *. Since you are talking about passing an object from QAbstractItemModel::data, then I suppose that you want to provide a pointer to the object, is this correct? If so, then declare it like this:

typedef MyType * MyTypeStar
Q_DECLARE_METATYPE(MyTypeStar);

This will make MyType * known to the meta-type system.

If you want to pass around the object itself, then declare the way you tried, but make sure that you properly define your type:

Q_DECLARE_METATYPE: This macro makes the type Type known to QMetaType as long as it provides a public default constructor, a public copy constructor and a public destructor. It is needed to use the type Type as a custom type in QVariant.

Answer 2

Why wont put it inside QVariant as QObject ? qVariantFromValue(youObjectPointer)