How to access qabstractlistmodel derived class object as a property of another class from qml?

Question

Iam designing a qml page which consists of 3 lists. I want the data to be displayed in these lists as model from cpp. Can i have all these 3 models as properties from a single class.

I have a class derived from qabstractlistmodel to use as model. I want this model as a property from another class which is bind to qml using qqmlcontextproperty.

ie. I could be able to access this model as a property.

class ToDoModel : public QAbstractListModel
{
    Q_OBJECT
    ...
}

class HelperClass : public QObject
{
    Q_OBJECT
    Q_PROPERTY(ToDoModel todoModel READ todoModel CONSTANT)
public:
    explicit HelperClass(QObject *parent = nullptr);

    ToDoModel* todoModel() const;

signals:

public slots:

private:
    ToDoModel *_todoModel;
};

int main(int argc, char *argv[])
{
HelperClass helperClass;
engine.rootContext()->setContextProperty(QStringLiteral("helperClass"), &helperClass);
...
}

It shows the error :

Unable to handle unregistered datatype 'ToDoModel' for property 'HelperClass::todoModel'

Answer 1

A QObject, like the QAbstractListModel, is not copied, so in that case you must return the pointer. So in general if T is a QObject then if you expose it as a property it must be Q_Property(T* name ...).

So in your case it changes to:

class HelperClass : public QObject
{
    Q_OBJECT
    Q_PROPERTY(ToDoModel* todoModel READ todoModel CONSTANT)
    // ...