Parser for Amazon Marketplace Web Service XSD's: Retrieves the list of DataNodes (referenced as Product Category XSDs) and ProductType for the corresponding DataNode

Gemfile

source 'https://rubygems.org'

gem 'mws-rb', git: 'https://github.com/veeqo/mws-rb.git'

xsd_parser.rb

##
# # Usage Example
# parser = AmazonMWS::XSDParser.new
# parser.product_data_list # => ['ClothingAccessories', 'Clothing', 'Miscellaneous', ...]
# parser.product_type_list('Clothig') # => ['Shirt', 'Sweater', 'Pants', ...]
##
module AmazonMWS
  class XSDParser
    attr_reader :xsd_path

    def initialize(options = {})
      @xsd_path = options.fetch(:xsd_path, default_xsd_path)
    end

    def product_data_list
      # we still need to extract value, because xpath returns attribute
      # as a nokogiri object
      xml_doc('product').xpath(product_data_query).map(&:value)
    end

    def product_type_list(category)
      filename = filename_for_category(category)
      xml_doc(filename).xpath(product_type_query).map do |product_type|
        product_type.attributes.values.first.value
      end
    end

    private

    def filename_for_category(category)
      {
        "Clothing" => "ProductClothing",
        "SoftwareVideoGames" => "SWVG",
        "GiftCard" => "GiftCards"
      }.fetch(category, category)
    end

    def default_xsd_path
      MWS::API::Feeds::XSD_PATH
    end

    def xml_doc(filename)
      Nokogiri::XML(File.read(File.join(xsd_path, "#{filename.camelize}.xsd")))
    end

    def product_data_query
      "//xsd:element[@name='ProductData']/xsd:complexType/xsd:choice/xsd:element/@ref"
    end

    def product_type_complex_type_query
      "//xsd:element[@name='ProductType']/xsd:complexType/xsd:choice/xsd:element"
    end

    def product_type_simple_type_query
      "//xsd:element[@name='ProductType']/xsd:simpleType/xsd:restriction/xsd:enumeration"
    end

    def clothing_type_query
      "//xsd:element[@name='ClothingType']/xsd:simpleType/xsd:restriction/xsd:enumeration"
    end

    def product_type_query
      [ product_type_complex_type_query,
        product_type_simple_type_query,
        clothing_type_query
      ].join(" | ")
    end
  end
end

xsd_parser_spec.rb

require 'spec_helper'

describe AmazonMWS::XSDParser do
  shared_examples 'list of nodes' do
    it { should_not be_empty }

    it 'returns node names' do
      expect(subject.first).to be_kind_of(String)
    end
  end

  describe "#product_data_list" do
    subject { described_class.new.product_data_list }

    it_behaves_like 'list of nodes'
  end

  describe "#product_type_list" do
    subject { described_class.new.product_type_list('Home') }

    it_behaves_like 'list of nodes'
  end
end