Net:HTTP enabled URI Validator for Rails 3

environment.rb

...
require 'uri_validator'

model.rb

validates :url, :presence => true, :uri => { :format => /(^$)|(^(http|https):\/\/[a-z0-9]+([\-\.]{1}[a-z0-9]+)*\.[a-z]{2,5}(([0-9]{1,5})?\/.*)?$)/ix }

uri_validator.rb

require 'net/http'

# Thanks Ilya! http://www.igvita.com/2006/09/07/validating-url-in-ruby-on-rails/
# Original credits: http://blog.inquirylabs.com/2006/04/13/simple-uri-validation/
# HTTP Codes: http://www.ruby-doc.org/stdlib/libdoc/net/http/rdoc/classes/Net/HTTPResponse.html

class UriValidator < ActiveModel::EachValidator
  def validate_each(object, attribute, value)
    raise(ArgumentError, "A regular expression must be supplied as the :format option of the options hash") unless options[:format].nil? or options[:format].is_a?(Regexp)
    configuration = { :message => "is invalid or not responding", :format => URI::regexp(%w(http https)) }
    configuration.update(options)
    
    if value =~ configuration[:format]
      begin # check header response
        case Net::HTTP.get_response(URI.parse(value))
          when Net::HTTPSuccess then true
          else object.errors.add(attribute, configuration[:message]) and false
        end
      rescue # Recover on DNS failures..
        object.errors.add(attribute, configuration[:message]) and false
      end
    else
      object.errors.add(attribute, configuration[:message]) and false
    end
  end
end

An updated format: /(^$)|(^(http|https):\/\/[a-z0-9]+([\-\.]{1}[a-z0-9]+)*\.[a-z]{2,5}(:[0-9]{1,5})?([\/].*)?$)/ix

Most importantly it fixes an error in the original in which the colon before the port number was missing. It also allows for URLs that don't include a / after the domain (i.e. http://www.google.com)

This validation will fail if site redirects and returns 30X. Some sites use 30X in order to redirect to some inner page.

irb(main):001:0> v = "http://siemens.com"
=> "http://siemens.com"
irb(main):002:0> Net::HTTP.get_response(URI.parse(v))
=> #<Net::HTTPMovedPermanently 301 Moved Permanently readbody=true>

Easily fixable by changing line 16 to:

when Net::HTTPSuccess, Net::HTTPRedirection then true

This doesn't seem to work. Tried with http://google.com, http://www.google.com, http://google.com/. Also tried to apply the other 2 guys comments. No luck?

@valk works for me:

irb(main):006:0> r = /(^$)|(^(http|https):\/\/[a-z0-9]+([\-\.]{1}[a-z0-9]+)*\.[a-z]{2,5}(:[0-9]{1,5})?([\/].*)?$)/ix
=> /(^$)|(^(http|https):\/\/[a-z0-9]+([\-\.]{1}[a-z0-9]+)*\.[a-z]{2,5}(:[0-9]{1,5})?([\/].*)?$)/ix
irb(main):007:0> r =~ 'http://google.com'                                   => 0
irb(main):008:0> r =~ 'http://www.google.com'
=> 0
irb(main):009:0> r =~ 'http://google.com/'
=> 0
irb(main):010:0> 

No support for ftp://.... ?

@Server4001 you could easily add support to the regex for ftp://. Something like:

validates :url, :presence => true, :uri => { :format => URI::regexp(%w(http https ftp)) }

However, I think the Net::HTTP request would fail for FTP uris. You would need to modify the validator to check the validity of the FTP server.

Enter only url i.e http://www.flipkart.com then it doesnot validate it. It should also check if it is not a proper image url