polymorphic_mapping

# File actionpack/lib/action_dispatch/routing/polymorphic_routes.rb, line 177
        def polymorphic_mapping(record)
          if record.respond_to?(:to_model)
            _routes.polymorphic_mappings[record.to_model.model_name.name]
          else
            _routes.polymorphic_mappings[record.class.name]
          end
        end