Qt Model within a model? - c++

Question

I have a Qt model which could very well be a QAbstractListModel. Each "row" represents an object I have stored in a QList. I'm displaying this in QML in a ListView. However, each object has one property that happens to be an array of strings. I would like to display this as a ListView within the delegate that displays that row. But I don't know how to expose that model (for the string array property of the object) to QML. I can't expose it through the data function since Models are QObjects, which cannot be QVariants. I thought of using QAbstractItemModel instead, but I still don't know how to get a model for my ListView. In case it matters, I'm using Qt 5.0.0 release.

Answer 1

You can return QVariantList from your main QAbstractListModel and this can then be assigned as a model to your internal ListView that you have in the delegate. I have added a small example that has a very simple one row model with internal model as an example.
The c++ model class:
class TestModel : public QAbstractListModel
{
public:
enum EventRoles {
StringRole = Qt::UserRole + 1
};
TestModel()
{
m_roles[ StringRole] = "stringList";
setRoleNames(m_roles);
}
int rowCount(const QModelIndex & = QModelIndex()) const
{
return 1;
}
QVariant data(const QModelIndex &index, int role) const
{
if(role == StringRole)
{
QVariantList list;
list.append("string1");
list.append("string2");
return list;
}
}
QHash<int, QByteArray> m_roles;
};
Now you can set this model to QML and use it like this:
ListView {
anchors.fill: parent
model: theModel //this is your main model
delegate:
Rectangle {
height: 100
width: 100
color: "red"
ListView {
anchors.fill: parent
model: stringList //the internal QVariantList
delegate: Rectangle {
width: 50
height: 50
color: "green"
border.color: "black"
Text {
text: modelData //role to get data from internal model
}
}
}
}
}