How to Extract a form value from a line of HTML in Ruby

Question

I would like to extract the value of some form tags. The value is unknown to me at runtime.

I have found several threads that come close, but they all focus on HTML parsing and scraping.

I already have the HTML source and the names of the form fields that I need the value for.

example:

<input type="hidden" name="currentRackU" id="currentRackU" value="11">

I can use a regex to get to 'id="currentRackU" value=' but I now need to get the next characters until the closing quotes.

Obligatory link: [Don't parse HTML with regular expressions](http://stackoverflow.com/a/1732454/125816). — Sergio Tulentsev, Jul 13 '12 at 06:24

score 1 · Answer 1 · answered Jul 13 '12 at 19:40

How about this one-liner with nokogiri?

require 'nokogiri'
s = '<input type="hidden" name="currentRackU" id="currentRackU" value="11">'
Nokogiri::XML.parse(s).root.attributes['id'].value # currentRackU

You might need to run gem install nokogiri if you don't have nokogiri installed.

score 0 · Answer 2 · answered Jul 13 '12 at 07:09

0

When it comes to extracting data from HTML/XML documents, I usually use the gem nokogiri - it does the job well and in an elegant manner.

answered Jul 13 '12 at 07:09

ksol

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score 0 · Accepted Answer · answered Jul 13 '12 at 07:30

While it's true that HTML/XML shouldn't necessarily be parsed with a regular expression, here's something that may help you. It scans the tag and returns a hash of the attributes and their values:

html = '<input type="hidden" name="currentRackU" id="currentRackU" value="11">'
Hash[html.scan(/(\w+)="(.*?)"/)]
#=> {"type"=>"hidden", "name"=>"currentRackU", "id"=>"currentRackU", "value"=>"11"}

How to Extract a form value from a line of HTML in Ruby

3 Answers3