How do I do a regex search in Nokogiri for text that matches a certain beginning?

Question

Given:

require 'rubygems'
require 'nokogiri'
value = Nokogiri::HTML.parse(<<-HTML_END)
"<html>
<body>
  <p id='para-1'>A</p>
  <div class='block' id='X1'>
    <h1>Foo</h1>
    <p id='para-2'>B</p>
  </div>
  <p id='para-3'>C</p>
  <h2>Bar</h2>
  <p id='para-4'>D</p>
  <p id='para-5'>E</p>
  <div class='block' id='X2'>
    <p id='para-6'>F</p>
  </div>
</body>
</html>"
HTML_END

I want to do something like what I can do in Hpricot:

divs = value.search('//div[@id^="para-"]')

How do I do a pattern search for elements in XPath style?
Where would I find the documentation to help me? I didn't see this in the rdocs.

PSA: For those attempting more complex regex, this is likely what you're looking for: http://stackoverflow.com/questions/649963/nokogiri-searching-for-div-using-xpath — DreadPirateShawn, Feb 01 '15 at 06:19

score 75 · Accepted Answer · edited Mar 02 '13 at 09:10

75

Use the xpath function starts-with:

value.xpath('//p[starts-with(@id, "para-")]').each { |x| puts x['id'] }

edited Mar 02 '13 at 09:10

the Tin Man

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answered Oct 12 '09 at 18:28

Aaron Patterson

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33

Wow, Aaron himself just answered it! – khelll Oct 13 '09 at 03:56
7

Author of Nokogiri and RoR core team member. – khelll May 18 '14 at 12:14

score 19 · Answer 2 · edited Mar 02 '13 at 09:10

19

divs = value.css('div[id^="para-"]')

edited Mar 02 '13 at 09:10

the Tin Man

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answered Jun 25 '10 at 22:48

insane.dreamer

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this is a life saver – Onichan Sep 14 '16 at 21:43

andre-r · Answer 3 · 2014-08-11T08:08:26.003

3

And some docs you're seeking:

Nokogiri: http://nokogiri.org/
XPath: http://www.w3.org/TR/xpath20/
CSS3 Selectors: http://www.w3.org/TR/selectors/

edited Aug 11 '14 at 08:08

answered Oct 12 '09 at 22:44

andre-r

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karwan · Answer 4 · 2016-01-08T13:37:40.250

Nokogiri::XML::Node.send(:define_method, 'xpath_regex') { |*args|
  xpath = args[0]
  rgxp = /\/([a-z]+)\[@([a-z\-]+)~=\/(.*?)\/\]/
  xpath.gsub!(rgxp) { |s| m = s.match(rgxp); "/#{m[1]}[regex(.,'#{m[2]}','#{m[3]}')]" }
  self.xpath(xpath, Class.new {
    def regex node_set, attr, regex
      node_set.find_all { |node| node[attr] =~ /#{regex}/ }
    end
  }.new)
}

Usage:

divs = Nokogiri::HTML(page.root.to_html).
  xpath_regex("//div[@class~=/axtarget$/]//div[@class~=/^carbo/]")

How do I do a regex search in Nokogiri for text that matches a certain beginning?

4 Answers4

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