てきとーなamazon検索

require "open-uri"

require "rexml/document"

require "uri"
module AWSECommerceServiceItemSearch
  def camelize(underscored)

    if /^[a-z]+(_[a-z]+)*=?$/ =~ underscored

      underscored.sub(/^(.)/) { $1.upcase }.gsub(/_(.)/) { $1.upcase }

    else

      underscored

    end

  end
  module_function :camelize
  class Request

    @@base_url = "http://webservices.amazon.co.jp/onca/xml"
    def initialize(id)

      @params = {}

      self.service = "AWSECommerceService"

      self.operation = "ItemSearch"

      self.AWSAccessKeyId = id

    end
    def search

      res = nil

      open(request_url) {|f| res = Response.new(f.read)}

      return res

    end
    def request_url

      @@base_url + "?" + query_string

    end
    def query_string

      @params.collect {|param, value| param + "=" + value}.join("&")

    end
    def method_missing(name, *args)

      param = AWSECommerceServiceItemSearch::camelize(name.to_s)
      if /=$/ =~ param

        @params[param.chop] = URI.encode(args.join(","))

      else

        @params[param]

      end

    end

  end
  class Response

    def initialize(source)

      @root = (source.is_a? REXML::Element) ? source : REXML::Document.new(source).root

    end
    def [](name)

      path = AWSECommerceServiceItemSearch::camelize(name.to_s)

      elems = @root.get_elements(path)

      elems.collect {|elem| Response.new(elem)}

    end
    def method_missing(name, *args, &block)

      path = AWSECommerceServiceItemSearch::camelize(name.to_s)

      elem = @root.elements[path]

      elem ? Response.new(elem) : @root.send(name, *args, &block)

    end

  end
end

実行はこんな感じ。

s = AWSECommerceServiceItemSearch::Request.new("...")

s.search_index = "Books"

s.keywords = "Ruby"
s.search.items[:item].each {|i|

  puts i.item_attributes.title.text

}

追記
camelizeはあんまよくないかも。統一感のないAPIになるし。