QQmlPropertyMap, model

[wysota]

how would I then get the QML object to upadte when the value has changed?

Bind the object's property to a function call that will return the data or invoke some imperative code when contents of the model change.

I'm currently thinking I'll have to use a QQmlListProperty as my internal data storage for my QAbstractListModel derived object.

No, that's not a good idea.

- Make sure a data entry can only ever be modified through the QAbstractListModel derived object

That's always the proper approach.

[sBoff]

Bind the object's property to a function call that will return the data or invoke some imperative code when contents of the model change.

This is fine, I have the QML object's property bound to the a function (I can see it hitting the breakpoint where I return a value) however, this only gets called once while the QML object is loading. From that point on, it never updates despite the data changing (this the issue QQmlPropertyMap and the likes resolved). I guess the question then boils down to, how can I update the QML object when I know data that it references has been updated?

Edit: I've had a bit of a play with this and the only solution I can come up with is binding the QML object's value a C++ object's property and provide a NOTIFY signal

C++:
class Runtime : public QObject
{
    Q_OBJECT
    Q_PROPERTY(RuntimeData* data READ GetData NOTIFY modelChanged)
public:

C++:
class Runtime : public QObject
{
    Q_OBJECT
    Q_PROPERTY(RuntimeData* data READ GetData NOTIFY modelChanged)
public:

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The RuntimeData object is my QAbstractListModel derived object. In this object I've then created a Q_INVOKABLE member that retuns the data value base on an index (for now).

class RuntimeData : public QAbstractListModel
{
    Q_OBJECT
public:
    Q_INVOKABLE int GetData(int index)
    {
        if (index >= 0 && index < m_Data.count())
            return m_Data[index].Value().toInt();
        return 0;
    }

class RuntimeData : public QAbstractListModel
{
    Q_OBJECT
public:
    Q_INVOKABLE int GetData(int index)
    {
        if (index >= 0 && index < m_Data.count())
            return m_Data[index].Value().toInt();
        return 0;
    }

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Finally, its all working but there is a remaining issue. With this implementaion, anytime I have to update any data, I also have to emit the modelChanged signal to inform the QML to update. Hypothetically if I have 1000 data entries and 1000 QML objects bound to these, if one data item changes all QML objects will update.

Again, I feel like I must be missing something? Why is this so complicated?