Question

Currently I’m parsing a HTML document using Nokogiri and iterating through all the code tags like this:

html = Nokogiri::HTML(doc)
html.css("code").each do |code|
   # do something with code
   if /^@@@@/.match(code.text.split("\n")[0])
     return "this code element is at line blah"
   end     
end

I don’t have to use Nokogiri, it was just convenient to use to iterate through all the code elements.

In the case where the code tag begins with @@@@ then I want to be able to reference the line number in the document where that code tag occurred. Keep in mind that two code tags can be identical.

Answer 1

There are a couple reasons Nokogiri might be returning a line number of 0 for nodes retrieved using the HTML parser, both involving lbxml.

1. A bug in version 2.7.3 of libxml

Credit: Aaron Paterson AKA tenderlove https://github.com/sparklemotion/nokogiri/issues/closed#issue/347

2 . The version of Nokogiri that you are using is built against a different version of libxml than you currently have on your system.

This was my issue. I had libxml version 2.7.8 and was seeing this behavior. I had not installed the gem locally, so I went ahead and did that

$ sudo gem install nokogiri

If you already have the gem install it would be just be 1 extra step to uninstall it

$ gem uninstall nokogiri 
$ gem install nokogiri

Credit – Tin Man’s Answer to this question

To determine the version of libxml you are currently running

$nokogiri -v

My current setup (working)

ruby: 
engine: mri
version: 1.8.7
platform: universal-darwin10.0

libxml: 
loaded: 2.7.8
binding: extension
compiled: 2.7.8
nokogiri: 1.4.4