尝试使用feedzirra解析rss feed

Question

尝试从深层嵌套的内容中获取信息。想要获取rails中每个条目的TopicName和TopicID。

我得到的只是@content="\n \n \n

<entry>
    <id>...</id>
    <title type="text">Ground Water Awareness Week</title>
    <summary type="text"/>
    <updated>...</updated>
    <link rel="alternate" href="..."/>
    <link href="..."/>
    <content type="application/xml">
    <CatalogItems>
        <CatalogSource Acronym="..." OrganizationName="..."/>
            <CatalogItem Id="25743" CatalogUrl="..." AddedDateTime="..." ModifiedDateTime="...">
            <ContentItem TargetUrl="..." ContentType="text/xml" CreatedDateTime="..." ModifiedDateTime="..." PersistentUrl="..." Title="..." GUID="...">
            <content:SelectionSpec ClassList="" ElementList=""/>
            <content:Language Value="eng" Scheme="ISO 639-2"/>
            <content:Source Acronym="..." OrganizationName="..."/>
            <content:Topics Scheme="...">
                <content:Topic TopicId="27106" TopicName="drinking water safety"/>
                <content:Topic TopicId="27105" TopicName="Ground water"/>
                <content:Topic TopicId="27107" TopicName="clean drinking water"/>
            </content:Topics>
            </ContentItem>
        </CatalogItem>
    </CatalogItems>
    </content>
</entry>

feed_entry.rb

class FeedEntry < ActiveRecord::Base
  require 'feedzirra'

  def self.update_from_feed(feed_url)
      feed = Feedzirra::Feed.fetch_and_parse(feed_url)
      add_entries(feed.entries)
    end


  def self.add_entries(entries)
    entries.each do |entry|
      unless exists? :guid => entry.id
        create!(:name => entry.title, :summary => entry.summary, :url => entry.url, :published_at => entry.published, :guid => entry.id)
        # After entry is created
        # I then want to check if topic exists or not.  if not then create.
        # something like below
        CatalogItems.CatalogSource.content:Topics.each do |topic|
          Catagory.find_or_create_by_name(:name => TopicName)
        end
      end
    end
  end
end