check-uri.rb

## just some ways to check if a url exists

# method 1 - from Simone Carletti
require "net/http"
url = URI.parse("http://www.google.com/")
req = Net::HTTP.new(url.host, url.port)
res = req.request_head(url.path)

# method 2 - from some kid on the internet
require 'open-uri'
require 'net/http'

def remote_file_exists?(url)
  url = URI.parse(url)
  Net::HTTP.start(url.host, url.port) do |http|
    return http.head(url.request_uri).code == "200"
  end
end

# method 3 - from another kid on the internet in response method 2
require 'rubygems'
require 'rest-open-uri'

def remote_file_exist?(url)
  open( url , :method => :head).status rescue false
end

# method 4 - from http://rawsyntax.com/post/4544397323/url-validation-in-rails-3-and-ruby-in-general

require 'addressable/uri' 

class Example
  include ActiveModel::Validations

  ##
  # Validates a URL
  #
  # If the URI library can parse the value, and the scheme is valid
  # then we assume the url is valid
  #
  class UrlValidator < ActiveModel::EachValidator
    def validate_each(record, attribute, value)
      begin
        uri = Addressable::URI.parse(value)

        if !["http","https","ftp"].include?(uri.scheme)
          raise Addressable::URI::InvalidURIError
        end
      rescue Addressable::URI::InvalidURIError
        record.errors[attribute] << "Invalid URL"
      end
    end
  end

  validates :field, :url => true
end