While loading webpage: "undefined method `request_uri' for #"

Question

I'm trying to use Ruby to load a webpage over HTTP and check what its status code is. My code looks like this:

  require "net/http"
  @r = Net::HTTP.get_response(URI.parse(myURL))
  return @r.code

However, for some URLs (mostly ones pointing to weird stuff like web counters that won't give a proper response) I'm getting an undefined method request_uri for # exception. I've traced it back to line 380 of http.rb (I'm running Ruby 1.8), where it says:

def HTTP.get_response(uri_or_host, path = nil, port = nil, &block)
  if path
    host = uri_or_host
    new(host, port || HTTP.default_port).start {|http|
      return http.request_get(path, &block)
    }
  else
    uri = uri_or_host
    new(uri.host, uri.port).start {|http|
      return http.request_get(uri.request_uri, &block) <--- LINE 380
    }
  end
end

I'm quite lost as to what causes this exception. I would expect a URI::InvalidURIError, but not this.

Answer 1

Given a recognised scheme (e.g. http/https), a more specialised class will be instantiated. Otherwise a "generic" URI is created; the idea of a "request URI" only makes sense for some URI schemes.

Example:

irb(main):001:0> require 'uri'
=> true
irb(main):002:0> URI.parse('http://www.google.com/').class
=> URI::HTTP
irb(main):003:0> URI.parse('https://www.google.com/').class
=> URI::HTTPS
irb(main):004:0> URI.parse('foo://www.google.com/').class
=> URI::Generic
irb(main):005:0> URI.parse('http://www.google.com/').respond_to?(:request_uri)
=> true
irb(main):006:0> URI.parse('https://www.google.com/').respond_to?(:request_uri)
=> true
irb(main):007:0> URI.parse('foo://www.google.com/').respond_to?(:request_uri)
=> false

So one of the URIs you're parsing has a strange scheme -- even though it's a valid URI -- that's all.