creation_attributes

# File activerecord/lib/active_record/associations/association.rb, line 179
        def creation_attributes
          attributes = {}

          if (reflection.has_one? || reflection.collection?) && !options[:through]
            attributes[reflection.foreign_key] = owner[reflection.active_record_primary_key]

            if reflection.options[:as]
              attributes[reflection.type] = owner.class.base_class.name
            end
          end

          attributes
        end