RUBY - web scraping - (OpenURI::HTTPError)

Question

I'm trying to code a simple web scraping in ruby. It works till 29th url then I get this error message:

C:/Ruby193/lib/ruby/1.9.1/open-uri.rb:346:in `open_http': 500 Internal Server Er
ror (OpenURI::HTTPError)
        from C:/Ruby193/lib/ruby/1.9.1/open-uri.rb:775:in `buffer_open'
        from C:/Ruby193/lib/ruby/1.9.1/open-uri.rb:203:in `block in open_loop'
        from C:/Ruby193/lib/ruby/1.9.1/open-uri.rb:201:in `catch'
        from C:/Ruby193/lib/ruby/1.9.1/open-uri.rb:201:in `open_loop'
        from C:/Ruby193/lib/ruby/1.9.1/open-uri.rb:146:in `open_uri'
        from C:/Ruby193/lib/ruby/1.9.1/open-uri.rb:677:in `open'
        from C:/Ruby193/lib/ruby/1.9.1/open-uri.rb:33:in `open'
        from test.rb:24:in `block (2 levels) in <main>'
        from test.rb:18:in `each'
        from test.rb:18:in `block in <main>'
        from test.rb:14:in `each'
        from test.rb:14:in `<main>'

My code:

require 'rubygems'  
require 'nokogiri'  
require 'open-uri'  

aFile=File.new('data.txt', 'w')

ag = 0
  for i in 1..40 do
    agenzie = ag + 1

    #change url parameter 

    url = "http://www.infotrav.it/dettaglio.do?sort=*RICOVIAGGI*&codAgenzia=" + "#{ ag }"  
    doc = Nokogiri::HTML(open(url))
    aFile=File.open('data.txt', 'a')
    aFile.write(doc.at_css("table").text)
    aFile.close
  end

Do you have some ideas to solve it? Thanks!

aS

Answer 1

Here, let me clean it up for you:

File.open('data.txt', 'w') do |aFile|
  (1..40).each do |ag|
    url = "http://www.infotrav.it/dettaglio.do?sort=*RICOVIAGGI*&codAgenzia=#{ag}"
    response = open(url) rescue nil
    next unless response
    doc = Nokogiri::HTML(response)
    aFile << doc.at_css("table").text
  end
end

notes:

• using block style File.open means the file will close itself when the block exits
• use each to iterate instead of for loop