Listview with custom elements (QAbstractListModel with derived classes)

Ayekey

Hello, I'm working on a Qt qml application which has a listview containing multiple different items each with their own unique properties.
I've managed to make it work using a QAbstractListModel, however the implementation isn't modular and expanding upon my current method won't be pretty.

QVariant ProcessingModel::data(const QModelIndex &index, int role) const
{
  if (index.row() < 0 || index.row() >= m_model.count())
          return QVariant();

  ImageProcess* process = m_model[index.row()];
  switch(role)
  {
    default:
      return QVariant();
    case TypeNameRole:
      return process->type_name();
    case TypeRole:
      return process->type();
    case ErosionSize:
      return static_cast<Erode*>(process)->erosion_size();
    case DilationSize:
      return static_cast<Dilate*>(process)->dilation_size();
  }
}

QHash<int, QByteArray> ProcessingModel::roleNames() const {
    QHash<int, QByteArray> roles;
    roles[TypeNameRole] = "type_name";
    roles[TypeRole] = "type";
    roles[ErosionSize] = "erosion_size";
    roles[DilationSize] = "dilation_size";
    return roles;
}

The application currently looks like this:

This list currently contains two items: Erode and Dilate, each item is expandable showing their own custom menu. (in the image Dilate is expanded showing some text and a slider which changes the dilation_size)

How can i make a QAbstractListModel using derived classes?
Or is there something else I should use instead?

Any feedback or advice is welcome, thanks in advance.

Ayekey

Fixed it by moving the data aspect to the derived classes (du-duh)
Only thing that still stings is the roleNames function requiring to ask each derived class for its rolenames, for which i don't see an easy solution. but it is only one additional line for each derived class, which I can live with.

QVariant ProcessingModel::data(const QModelIndex &index, int role) const
{
  if (index.row() < 0 || index.row() >= m_model.count())
          return QVariant();

  return m_model[index.row()]->getData(role);
}

QHash<int, QByteArray> ProcessingModel::roleNames() const {
    QMultiHash<int, QByteArray> roles;
    roles.insert(ImageProcess::TypeNameRole, "type_name");
    roles.insert(ImageProcess::TypeRole, "type");
    roles.unite(Erode::roleNames());
    roles.unite(Dilate::roleNames());
    return std::move(roles);
}

If anyone has any suggestions on how to improve the roleNames feel free to share.