这假定每个Offer元素始终具有相同的子节点(尽管它们可以为空):

This assumes that each Offer element always has the same child nodes (though they can be empty):

CSV.open('output.csv', 'wb') do |csv|
  doc.search('Offer').each do |x|
    csv << x.search('*').map(&:text)
  end
end

并获取标头(从第一个Offer元素开始):

And to get headers (from the first Offer element):

CSV.open('output.csv', 'wb') do |csv|
  csv << doc.at('Offer').search('*').map(&:name)
  doc.search('Offer').each do |x|
    csv << x.search('*').map(&:text)
  end
end

search和at是Nokogiri函数，可以采用XPath或CSS选择器字符串. at将返回元素的第一次出现； search将提供匹配元素的数组(如果找不到匹配项，则为空数组).在这种情况下，*将选择作为当前节点的直接子代的所有节点.

search and at are Nokogiri functions that can take either XPath or CSS selector strings. at will return the first occurrence of an element; search will provide an array of matching elements (or an empty array if no matches are found). The * in this case will select all nodes that are direct children of the current node.

name和text也是Nokogiri函数(用于元素). name提供元素的名称； text提供节点的文本或CDATA内容.

Both name and text are also Nokogiri functions (for an element). name provides the element's name; text provides the text or CDATA content of a node.