Use nokogiri with xpath - ruby

Question

How can i use nokogiri, to fetch image via xpath, but my main problem is that, i could have this div, but didn't have image:
image_node = #get_doc.xpath( '//*[#id="recaptcha_image"]/img/#src').map {|a| a.value }
#binding.pry
if image_node != nil
rec = Net::HTTP.get( URI.parse( "#{image_node['src']}" ) )
end
but i get
in `[]': can't convert String into Integer (TypeError)
how is it correct to use?
some part of html:
<div id="recaptcha_widget" style="display: none">
<div id="recaptcha_image">
<img *****>
</div>
<input type="text" id="recaptcha_response_field" name="recaptcha_response_field"
style="width: 295px">

Answer 1

I recommend CSS over XPath for most HTML queries, and many XML ones. Using CSS makes this very "visible":
require 'nokogiri'
doc = Nokogiri::HTML(<<EOT)
<div id="recaptcha_widget" style="display: none">
<div id="recaptcha_image">
<img src="path_to_image.jpg">
</div>
<input type="text" id="recaptcha_response_field" name="recaptcha_response_field" style="width: 295px">
EOT
doc.at('#recaptcha_widget img')['src'] # => "path_to_image.jpg"
how to do check, if i have div, but didn't have image?
How do you check if you didn't have the embedded <img> tag inside the <div>? Break your lookup into two parts, and check for a nil:
require 'nokogiri'
doc = Nokogiri::HTML(<<EOT)
<div id="recaptcha_widget" style="display: none">
<div id="recaptcha_image">
<img src="path_to_image.jpg">
</div>
<div id="recaptcha_image2">
</div>
<input type="text" id="recaptcha_response_field" name="recaptcha_response_field" style="width: 295px">
EOT
img = doc.at('#recaptcha_widget img')
img_src = img['src'] # => "path_to_image.jpg"
If the <img> tag doesn't exist you'll get nil:
img = doc.at('#recaptcha_widget2 img') # => nil
From that point you'd continue with a check to see if img was set:
if (img)
# ...do something...
end
Or, use a trailing rescue to capture the nil-exception and assign nil to img_src then test for it:
img_src = doc.at('#recaptcha_widget img')['src'] rescue nil # => "path_to_image.jpg"
img_src = doc.at('#recaptcha_widget2 img')['src'] rescue nil # => nil
if (img_src)
# do something
end