Which version of xpath that Nokogiri support? - ruby

Question

I can't find an official statement of the xpath version that Nokogiri supports. Anyone can help me with it? In fact I want to extract some elements that have an attribute start with specified sub string. For example, I want to get all Book elements that have a category attribute start with the character C. How to do this with nokogiri?
<?xml version="1.0" encoding="ISO-8859-1"?>
<!-- Edited by XMLSpy?-->
<bookstore>
<book category="COOKING">
<title lang="en">Everyday Italian</title>
<author>Giada De Laurentiis</author>
<year>2005</year>
<price>30.00</price>
</book>
<book category="CHILDREN">
<title lang="en">Harry Potter</title>
<author>J K. Rowling</author>
<year>2005</year>
<price>29.99</price>
</book>
<book category="WEB">
<title lang="en">XQuery Kick Start</title>
<author>James McGovern</author>
<author>Per Bothner</author>
<author>Kurt Cagle</author>
<author>James Linn</author>
<author>Vaidyanathan Nagarajan</author>
<year>2003</year>
<price>49.99</price>
</book>
<book category="WEB">
<title lang="en">Learning XML</title>
<author>Erik T. Ray</author>
<year>2003</year>
<price>39.95</price>
</book>
</bookstore>

Answer 1

I don't know which specific version of XPath Nokogiri supports. But, you can do this:
I want to get all book elements that have a category attribute start with the character C.
using XPath's starts-with:
doc = Nokogiri::XML(your_xml)
doc.search('//book[starts-with(#category, "C")]').each { |e| puts e['category'] }
# output is:
# COOKING
# CHILDREN
You could also use a CSS3 "begins with" selector:
doc = Nokogiri::XML(your_xml)
doc.search('book[category^=C]').each { |e| puts e['category'] }
# output is:
# COOKING
# CHILDREN