ruby - 如何基于属性从XML获取后代节点

Question

我正在尝试获取节点的后代子代：

require 'nokogiri'

@doc = Nokogiri::XML(File.open('data/20160521RHIL0.xml'))
nom_id = @doc.xpath('//race/nomination/@id')

race_id.each do |x|
  puts race_id.traverse {|race_id| puts nom_id }
end

我正在查看两种信息来源：


XML:Node的文档，其中包含

Nokogiri::XML::Node#children

sparklemotion的 Cheat-sheet：

node.traverse {|node| } # yields all children and self to a block, _recursivel

这是我的测试XML：

<meeting id="42977">
  <race id="215411">
    <nomination number="8" saddlecloth="8" horse="Chipanda" id="198926" />
    <nomination number="2" saddlecloth="2" horse="Chifries" id="198965" />
    <nomination number="1" saddlecloth="1" horse="Itpanda" id="199260" />
  </race>
  <race id="215412">
    <nomination number="1" saddlecloth="1" horse="Ruby" id="199634" />
    <nomination number="2" saddlecloth="2" horse="Gems" id="208926" />
    <nomination number="3" saddlecloth="3" horse="Rock" id="122923" />
  </race>
</meeting>

我可以使用XPath轻松获得竞赛 id：

require 'nokogiri'                                                                                                                      

  @doc = Nokogiri::XML(File.open('data/20160521RHIL0.xml'))                                                                               

  race_id = @doc.xpath('//race/@id')                                                                                                      
  nom_id = @doc.xpath('//race/nomination/@id')  

  ...
  215411
  215412

如何获取节点提名ID和 race_id 215411的编号并将其存储到哈希（如下所示）中？

{215411 => [{id:198926, number:8},{id:198965, number:2}]}

Answer 1

require 'nokogiri'

# xml data
str =<<-EOS
<meeting id="42977">
  <race id="215411">
    <nomination number="8" saddlecloth="8" horse="Chipanda" id="198926" />
    <nomination number="2" saddlecloth="2" horse="Chifries" id="198965" />
    <nomination number="1" saddlecloth="1" horse="Itpanda" id="199260" />
  </race>
  <race id="215412">
    <nomination number="1" saddlecloth="1" horse="Ruby" id="199634" />
    <nomination number="2" saddlecloth="2" horse="Gems" id="208926" />
    <nomination number="3" saddlecloth="3" horse="Rock" id="122923" />
  </race>
</meeting>
EOS

# create doc
doc = Nokogiri::XML(str)

# clean; via http://stackoverflow.com/a/1528247
doc.xpath('//text()[not(normalize-space())]').remove

# parse doc
parsed_doc = doc.xpath('//race').inject({}) {|h,x| h[x.get_attribute('id').to_i] = x.children.map {|y| {id: y.get_attribute('id').to_i, number: y.get_attribute('number').to_i}}; h}
# {215411=>
#  [{:id=>198926, :number=>8},
#   {:id=>198965, :number=>2},
#   {:id=>199260, :number=>1}],
# 215412=>
#  [{:id=>199634, :number=>1},
#   {:id=>208926, :number=>2},
#   {:id=>122923, :number=>3}]}

# select via id
parsed_doc.select {|k,v| k == 215411}
# {215411=>
#  [{:id=>198926, :number=>8},
#   {:id=>198965, :number=>2},
#   {:id=>199260, :number=>1}]}

这是单线多线：

parsed_doc = doc.xpath('//race').inject({}) do |h,x|
  h[x.get_attribute('id').to_i] = x.children.map do |y|
    {
      id: y.get_attribute('id').to_i,
      number: y.get_attribute('number').to_i
    }
  end
  h
end