Setting a HTTP user agent with mechanize?

Question

I'm having difficulty setting the user-agent. As you can see my custom user_agent_alias is not being returned. Can someone please explain why this isn't working and how I can fix this?

require 'rubygems'
require 'mechanize'
require 'nokogiri'

m = Mechanize.new
m.user_agent_alias = 'My Custom User Agent'
page = m.get("http://whatsmyuseragent.com/")
html = Nokogiri::HTML(page.body)
puts html.xpath('//*[(@id = "body_lbUserAgent")]').map(&:content)

Below is the "user agent" being returned (not what I set):

Mechanize/2.7.3 Ruby/2.0.0p353 (http://github.com/sparklemotion/mechanize/)

Answer 1

Turns out that the issue was that user_agent_alias requires a specific type. All acceptable types are as follows:

• Linux Firefox (3.6.1)
• Linux Konqueror (3)
• Linux Mozilla
• Mac Firefox (3.6)
• Mac Mozilla
• Mac Safari (5)
• Mac Safari 4
• Mechanize (default)
• Windows IE 6
• Windows IE 7
• Windows IE 8
• Windows IE 9
• Windows Mozilla
• iPhone (3.0)
• iPad
• Android (Motorola Xoom)

Working code:

require 'rubygems'
require 'mechanize'

m = Mechanize.new
m.user_agent_alias = 'Mac Safari 4'
page = m.get("http://whatsmyuseragent.com/")
html = Nokogiri::HTML(page.body)
puts html.xpath('//*[(@id = "body_lbUserAgent")]').map(&:content)

Answer 2

It is actually possible to set any user agent string: you have to use the method Mechanize::Agent#user_agent= instead of Mechanize::Agent#user_agent_alias=.

So if you change your example to:

m = Mechanize.new
m.user_agent = 'My Custom User Agent'
page = m.get("http://whatsmyuseragent.com/")

Then it works.