Scraping a web page with Nokogiri and mailing the results with ActionMailer

camera_price_buster.rb

require 'nokogiri'
require 'open-uri'

require_relative 'SimpleMailer'

doc = Nokogiri::HTML(open("http://www.camerapricebuster.co.uk/Canon/Canon-Lenses"))
# This xpath gathers the relevant table rows into an array.  The xpath was worked 
# out manually by using Developer Tools in Chrome and mapping the page structure into 
# an xpath query.  It looks for table rows containing both the 'img' element with the
# correct source attribute and an 'a' element with 'Canon-EF-lenses' in the href
# attribute.

elements = doc.xpath("//tr[td/a/img[@src='/i/ple1.gif'] and td/a[contains(@href,'Canon-EF-lenses')]]")
body = "\nFound #{elements.length} item#{elements.length < 1 || elements.length > 1 ? 's' : ''} "\
       "with lowest-ever price#{elements.length < 1 || elements.length > 1 ? 's' : ''}\n\n"

elements.each {
  |item|
  lens = item.xpath("td[2]/a/@href")
  price = item.xpath("td[2]/a/text()")

  url = "http://www.camerapricebuster.co.uk#{lens}"
  price = price.to_s.gsub("&pound;", "£")
  lens = lens.to_s.gsub("/Canon/Canon-EF-lenses/", "").gsub("-", " ")
  body += "Lens:\t#{lens}\nPrice:\t#{price}\nURL:\t#{url}\n\n\n"
}

email = SimpleMailer.simple_message('[email protected]', 'Camera Prices', body)
puts body
email.deliver

SimpleMailer.rb

require 'action_mailer'

ActionMailer::Base.smtp_settings = {
    :address => 'smtp.gmail.com',
    :port => 587,
    :domain => 'gmail.com',
    :user_name => '[email protected]',
    :password => 'senders-gmail-app-password',
    :authentication => :plain,
}

class SimpleMailer < ActionMailer::Base
  def simple_message(recipient, subject, message)
    mail(:from => '[email protected]',
         :to => recipient,
         :subject => subject,
         :body => message)
  end
end