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

Asked 12/10, 2009 at 18:0 Answered 8/1, 2016 at 13:31

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.

Etalon answered 12/10, 2009 at 18:0 Comment(1)

PSA: For those attempting more complex regex, this is likely what you're looking for: #650463 – Charlottetown 1/2, 2015 at 6:19

Use the xpath function starts-with:

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

Louisalouisburg answered 12/10, 2009 at 18:28 Comment(2)

Wow, Aaron himself just answered it! – Accomplishment 13/10, 2009 at 3:56

Author of Nokogiri and RoR core team member. – Accomplishment 18/5, 2014 at 12:14

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

Waftage answered 25/6, 2010 at 22:48 Comment(1)

this is a life saver – Ruddie 14/9, 2016 at 21:43

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/

Bathetic answered 12/10, 2009 at 22:44 Comment(0)

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/]")

Outstretched answered 8/1, 2016 at 13:31 Comment(0)

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