QAbstractListModel return a QObject and use it in qml?

bkamps

Hi,

I want to use the QAbstractListModel to fill a QML ListView and to set some properties of the ListView. But I also want to access the properties of the elements in my AbstractListModel.

For Example:

@class MyClass : public QObject
{
Q_OBJECT
Q_PROPERTY(int number READ Number WRITE SetNumber NOTIFY NumberChanged)
}@

@class MyClassListModel : public QAbstractListModel
{
Q_OBJECT

public:
MyClassListModel(QObject *parent = 0)
: QAbstractListModel(parent){}

int rowCount(const QModelIndex &parent = QModelIndex()) const;
QVariant data(const QModelIndex &index, int role) const;

private:
QList<MyClass*> mMyClasses
}@

@QVariant MyClassListModel::data(const QModelIndex &index, int role) const
{
if (!index.isValid())
return QVariant();

if (index.row() >= stringList.size())
    return QVariant();

if (role == Qt::DisplayRole)
    return mMyClasses.at(index.row());  
else
    return QVariant();

}@

return mMyClasses.at(index.row()); >>>>>>>>> Compiler tells me I cannot return this because it's not a QVariant. Not even when I register this class with Q_DECLARE_METATYPE(MyClass).

How is this possible?

This is the situation I want to archieve:

I have read somewhere you can "return" a (pointer) QObject from data() which then is set in the QML Listview (as a delegate).

If you then notify a property of that c++ QObject (MyClass number) the property will change in the QML ListView delegate.

If the property of one of my c++ objects in the list changes I don't want to refresh the whole QML ListView (or add/remove rows) but only update the properties of that object.

The QML object can then redraw itself instead of redrawing the whole list.

andre

What do you expect? You are returning a pointer to a MyClass object. You can wrap that in a QVariant if you want. You can not put an actual QObject in a QVariant, as that would require copying and QObjects can not be copied.

bkamps

This is the situation I want to archieve:

I have read somewhere you can “return” a (pointer) QObject from data() which then is set in the QML Listview (as a delegate).

If you then notify a property of that c++ QObject (MyClass number) the property will change in the QML ListView delegate.

If the property of one of my c++ objects in the list changes I don’t want to refresh the whole QML ListView (or add/remove rows) but only update the properties of that object.

The QML object can then redraw itself instead of redrawing the whole list.

mbrasser

Hi,

I'd suggest trying https://qt.gitorious.org/qt-labs/qml-object-model -- it has all of the underlying model stuff already implemented for you -- you just need to provide it with the list of objects.

Regards,
Michael