用于NodeSet的Ruby Nokogiri XML解析

Question

我在Ruby 2.6.5中使用Nokogiri解析某些XML时遇到问题。我已经查看了这里和其他帖子，但我似乎仍然无法获得Nokogiri。我尝试了不同的节点，所有的结果都是东西是NilClass。

require 'nokogiri'
xml_str = <<EOF
<?xml version="1.0" encoding="UTF-8"?>
<kml xmlns="http://www.opengis.net/kml/2.2" xmlns:atom="http://www.w3.org/2005/Atom" xmlns:gx="http://www.google.com/kml/ext/2.2" xmlns:kml="http://www.opengis.net/kml/2.2">
<Document>
<description><![CDATA[powered by <a href="http://www.wordpress.org">WordPress</a> &amp; <a href="https://www.mapsmarker.com">MapsMarker.com</a>]]></description>
<open>0</open>
<Style id="bar"><IconStyle><Icon><href>http://epic-curiousity.com/wp-content/uploads/leaflet-maps-marker-icons/bar.png</href></Icon></IconStyle></Style>
<name>Epic Curiousity</name>
<Placemark id="marker-35">
<styleUrl>#bar</styleUrl>
<name>Brasserie de Rochefort</name>
<TimeStamp><when>2014-06-13T07:06:01-08:00</when></TimeStamp>
<atom:author><atom:name>epiccuri</atom:name></atom:author>
<atom:link rel="related" href="http://epic-curiousity.com" />
<description><![CDATA[The Brasserie de Rochefort is located inside the Abbey of Notre-Dame de Saint-Rémy in Rochefort.  They're a trappist brewery and produce three very-fine beers:<ul><li>Trappistes Rochefort 6 - Dubbel 7.5% ABV</li><li>Trappistes Rochefort 8 - Belgian Strong Dark Ale 9.2% ABV</li><li>Trappistes Rochefort 10 - Quadrupel (Quad) 11.30% ABV</li></ul>You can find the brewery's homepage here: <a href="http://www.trappistes-rochefort.com/">http://www.trappistes-rochefort.com/</a><br /><br />Their BeerAdvocate page is located here: <a href="http://www.beeradvocate.com/beer/profile/207/">http://www.beeradvocate.com/beer/profile/207/</a>]]></description>
<address><![CDATA[Brasserie Scaillet, Rue de la Griotte, Rochefort, Belgium]]></address>
<Point>
<coordinates>5.199692,50.175346</coordinates>
</Point>
</Placemark>
</Document>
</kml>
EOF
doc = Nokogiri::XML(xml_str)
puts doc.class                      # => Nokogiri::XML::Document
thing = doc.at_xpath("Document")
puts thing.class                    # ==> NilClass

有人知道为什么这没有被识别为节点集吗？我也尝试过，结果相同：

doc = Nokogiri::XML.parse(xml_str)

Answer 1

这是因为xml有名称空间，这些名称空间需要包含在xpath查询中：

document = doc.at_xpath('//xmlns:Document')
document.class 
=> Nokogiri::XML::Element
document_name = doc.at_xpath('//xmlns:Document/xmlns:name')
document_name.class 
=> Nokogiri::XML::Element
document_name.content
=> "Epic Curiousity"

要在atom中获取名称：name:

atom_name = doc.at_xpath('//atom:name')
atom_name.content
=> "Epic Curiousity"

Answer 2

我在文档中看到，您可以使用css来查找您想要的

puts doc.at_css("Document")
# show all node Document
puts doc.css("name")
# <name>Epic Curiousity</name>
# <name>Brasserie de Rochefort</name>
puts doc.css("Placemark name")
# <name>Brasserie de Rochefort</name>
puts doc.css("Document/name")
# <name>Epic Curiousity</name>