Q_ENUMS based model

[St.Stanislav]

Hello all!

I have faces with the following question: let's suppose that I have Q_ENUMS:

class ColorType{
	Q_GADGET
public:
    enum Value {
        RED_COLOR,
        GREEN_COLOR,
        BLUE_COLOR,
    };
    Q_ENUM(Value);

    static void registerQML() {
	qmlRegisterUncreatableType<ColorType>("My.Enums", 1, 0, "ColorType", "ColorType");
	qRegisterMetaType<ColorType::Value>("ColorType::Value");
    }
};

In the QML-side I have combobox, where I want to display this enum, but with the "correct" displaying style ("Red", "Green", "Blue"). So corresponding Q_ENUMS values should be connected with the combobox items. What is the most correct (and simple) way to do this?

[raven-worx]

@St-Stanislav
the most generic way (if you do not want to do static mapping) would most probably be to use QMetaEnum inside a QAbstractListModel and publish it to QML.
Otherwise you simply can use a ListModel and add each list item yourself with it with all custom roles you like.

[St.Stanislav]

Thank you for the reply!

So based on your answer, I have implemented it in the following way:

1. Have created ColorTypeModel:

class ColorTypeModel : public QAbstractListModel
{
    enum {
        ColorTypeIDRole = Qt::UserRole,
        ColorTypeNameRole
};

2. Have made it singleton:

public:
    static ColorTypeModel& Instance() {
        static ColorTypeModel colorTypeModel;
        return colorTypeModel;
    }
    virtual ~ColorTypeModel() {}
private:
    explicit ColorTypeModel(QObject *parent = nullptr);

3. Have added QStringList and static QMap anyway:

private:
    QStringList m_data;
    static QMap<ColorType::Value, QString> m_namesMap;

4. Then I have implemented fillModel() method and call it in the model's constructor:

void ColorTypeModel::fillModel()
{
    m_data.clear();
    const QMetaEnum metaEnum = QMetaEnum::fromType<ColorType::Value>();
    assert((m_namesMap.size() == metaEnum.keyCount()) && "ColorTypeModel map should be filled with names for the every enum item!");
    for (int i = 0; i < metaEnum.keyCount(); ++i) {
        m_data.append(ColorTypeModel::m_namesMap.value(static_cast<ColorType::Value>(metaEnum.value(i))));
    }
}

5. Have implemented in my backend class (which is set as ContextPropery) method to publish it to QML:

QVariant Backend::getColorTypeModel() const
{
    return QVariant::fromValue(&ColorTypeModel::Instance());
}

6. Have created ComboBox in QML and connect with the aforementioned model:

ComboBox {
    textRole: "colorTypeName"
    valueRole: "colorTypeID"
    model: backend.getColorTypeModel()
}

Everything works well! So here is my question: is my approach correct (and match with the described one in your reply)? And can it be simplified somewhere?