Try something like this. Use the data method of index.

bool CustomProxyModel::filterAcceptsRow(int source_row, const QModelIndex &source_parent) const
{
const QModelIndex sourceIndex = sourceModel()->index(source_row, 0, source_parent);
// Some how get the the role you require.
const QString filterElement = sourceIndex.data(role).toString();
return(filterElement.toLower().startsWith(m_filterText));
}

@VRonin Awesome thanks! I was able tho to just grab the 2 files and use them directly so yay!

This tree model is epic. It does 90% of what I wanted ! Now I just gotta figure out how to hide parent/groups, so I only see items, but that should be fine, super awesome, thanks!

Edit1. using sort filter model later to decide if I want to show parents/etc worked just fine, yay!

An example of myModel->setData(myCustomValue, Qt::UserRole + 1); ?