From: "Jesús Gabriel y Galán" <jgabrielygalan@...>
Date: 2010-10-06T05:52:03+09:00
Subject: Re: How can I count number of elements in an HTML page

On Tue, Oct 5, 2010 at 10:45 PM, Paul <tester.paul@gmail.com> wrote:
> Hi there, I'm using net/http to retrieve some html pages and now I
> want to count the number of items in a list on the page.  The
> response.body is stored as a string.
>
> The HTML looks something like this:
> ----
> <div class="first section">
>   <h1>
>      Section Heading I'm interested in:
>   </h1>
>   <ul>
>      <li>
>         <form action="foo" method="post" name="">
>           <button type="submit">foo</button>
>         </form>
>      </li>
>      <li>
>         <form action="bar" method="post" name="">
>            <button type="submit">bar</button>
>         </form>
>      </li>
>   </ul>
> </div>
>
> <div class="next section">
> ----
>
> So what I want to do is count the number of li's in a particular div
> section.  In this case the answer is 2. It might be more, it might be
> 0.
>
> I can find the section I want with a regex but I don't know how to
> iterate through the string looking for particular elements.  I was
> thinking about taking the section I'm interested in and saving it as
> an array and then iterating through each array element (html line)
> that way, but I thought there might be a quicker way to do it.
>
> suggestions?

I'd use Nokogiri. Off the top of my head, it would be something like (untested):

require 'nokogiri'

html_string=<<END
#[your html]
END

doc = Nokogiri::HTML(html_string)
puts doc.search("/div/ul/li").size

Maybe you will need to adjust the xpath search, but I think it should
be something like that.

Hope this helps,

Jesus.