Rails 1レコードで複数のURLパラメータを埋めるためのパッチ

helper_method_builder_ext.rb

# 1レコードで複数のURLパラメータを埋めるためのパッチ
# /users/1/posts/2 のとき Post モデルに additional_path_args を以下のように定義すれば
# url_for(post) や link_to post と書けるようになる。
# def additional_path_args
#   user
# end
module HelperMethodBuilderExt
  def handle_model(record)
    named_route, args = super
    [named_route, expand_args(args, record)]
  end

  def handle_list(list)
    named_route, args = super
    [named_route, expand_args(args, list.last)]
  end

  private

  def expand_args(args, record = nil)
    args = expand_last_arg(args, record)
    args.inject([]) do |result, arg|
      if !arg.is_a?(Symbol) && !arg.is_a?(String) && !arg.is_a?(Class)
        model = arg.to_model
        if model.respond_to?(:additional_path_args)
          result.push(*Array(model.additional_path_args))
        end
      end
      result << arg
    end
  end

  def expand_last_arg(args, record)
    if !record.nil? && !record.is_a?(Symbol) && !record.is_a?(String) && !record.is_a?(Class)
      model = record.to_model
      if !model.persisted? && model.respond_to?(:additional_path_args)
        args += Array(model.additional_path_args)
      end
    end
    args
  end
end
ActionDispatch::Routing::PolymorphicRoutes::HelperMethodBuilder.send(:prepend, HelperMethodBuilderExt)