Specialization of DataAccess.page that returns models instead of cursor objects.

def page_models(self, constructor, paging, constraints=None, *, columns=None, order_by=None):
    """Specialization of DataAccess.page that returns models instead of cursor objects."""
    records, count = self.page(constructor.table_name, paging, constraints, columns=columns,
                               order_by=order_by)
    return ([constructor(r) for r in records], count)