polymorphic_mapping

# File actionpack/lib/action_dispatch/routing/polymorphic_routes.rb, line 330
            def polymorphic_mapping(target, record)
              if record.respond_to?(:to_model)
                target._routes.polymorphic_mappings[record.to_model.model_name.name]
              else
                target._routes.polymorphic_mappings[record.class.name]
              end
            end