Ruby on rails 无法从Amazon生产API获取项目详细信息

我正在使用获取项目详细信息。我可以得到一切，除了，项目描述，请建议我如何才能得到项目描述。请查看我想得到的。我选择了描述

查找我的配置

Gemfile

 gem 'amazon_product', '~> 3.0', '>= 3.0.1'

服务/amazon_service.rb

class AmazonService
    def initialize(params)
        @ItemPage = params[:ItemPage]
        @keyword = params[:keyword]
        @book_id = params[:book_id]
        $req = AmazonProduct['us']
        $req.configure do |c|
        c.key    = ENV['AWS_access_key_id']
        c.secret = ENV['AWS_secret_key']
        c.tag    = ENV['associate_tag']
    end
    end
    def itemlookup`enter code here`
        $req << {
        :operation    => 'ItemLookup',
        :search_index => 'Books',
        :Keywords => 'Book',
        :IdType => 'ISBN',
        :ItemId => @book_id,
        :response_group => ['ItemAttributes','Images'], 
    }
    $req.get
    end
end

---

产品说明存储在“编辑评论”节点下

EditorialReviews:
    EditorialReview:
      Source: Product Description
      Content: '<ul><li> Front Opening, Long Sleeve, Pure Color, Patternless,
        Draped, Scarf Hem, Stretch, Loose Style, Textured, Ruffled, </li><li>
        The model is about 5.2Ft in height.</li></ul><table border="1" cellpadding="1"
        cellspacing="1" width="200"><tr><td>Asian Size</td><td>International Size</td><td>US
        Size</td><td>Bust Girth</td><td>Waist Girth</td><td>Hip Girth</td><td>Arm

---

产品说明存储在“编辑评论”节点下

EditorialReviews:
    EditorialReview:
      Source: Product Description
      Content: '<ul><li> Front Opening, Long Sleeve, Pure Color, Patternless,
        Draped, Scarf Hem, Stretch, Loose Style, Textured, Ruffled, </li><li>
        The model is about 5.2Ft in height.</li></ul><table border="1" cellpadding="1"
        cellspacing="1" width="200"><tr><td>Asian Size</td><td>International Size</td><td>US
        Size</td><td>Bust Girth</td><td>Waist Girth</td><td>Hip Girth</td><td>Arm

product.description = Array.wrap(item.editorial_reviews).
                      find{|er| er['Source'] == 'Product Description'}.
                      try(:fetch, 'Content', nil)