Iconv::IllegalSequence when using www::mechanize

Question

I'm trying to do a little bit of webscraping, but the WWW:Mechanize gem doesn't seem to like the encoding and crashes :-/
The post request results in a 302 redirect (which mechanize follows, so far so good) and the resulting page seems to crash it :-/ I googled quite a bit, but nothing came up so far how to solve this. Any of you got an idea?

Code:

require 'rubygems'
require 'mechanize'

agent = WWW::Mechanize.new

agent.user_agent_alias = 'Mac Safari'
answer = agent.post('https://www.budget.de/de/reservierung/privatkunden/step1/schnellbuchung',
{"Country" => "Deutschland",
"Abholstation" => "Aalen",
"Abgabestation" => "Aalen",
"Abholdatum" => "26.02.2009",
"Abholzeit_stunde" => "13",
"Abholzeit_minute" => "30",
"Abgabedatum" => "28.02.2009",
"Abgabezeit_stunde" => "13",
"Abgabezeit_minute" => "30",
"CountryID" => "DE",
"AbholstationID"=>"AA1",
"AbgabestationID"=>"AA1"
}
)
puts answer.body

Error:

D:/Ruby/lib/ruby/gems/1.8/gems/mechanize-0.9.1/lib/www/mechanize/util.rb:29:in `iconv': "\204nderungen vorbe"... (Iconv::IllegalSequence)
from D:/Ruby/lib/ruby/gems/1.8/gems/mechanize-0.9.1/lib/www/mechanize/util.rb:29:in `to_native_charset'
from D:/Ruby/lib/ruby/gems/1.8/gems/mechanize-0.9.1/lib/www/mechanize/chain/response_header_handler.rb:29:in `handle'
from D:/Ruby/lib/ruby/gems/1.8/gems/mechanize-0.9.1/lib/www/mechanize/chain.rb:30:in `pass'
from D:/Ruby/lib/ruby/gems/1.8/gems/mechanize-0.9.1/lib/www/mechanize/chain/handler.rb:6:in `handle'
from D:/Ruby/lib/ruby/gems/1.8/gems/mechanize-0.9.1/lib/www/mechanize/chain/response_body_parser.rb:35:in `handle'
from D:/Ruby/lib/ruby/gems/1.8/gems/mechanize-0.9.1/lib/www/mechanize/chain.rb:30:in `pass'
from D:/Ruby/lib/ruby/gems/1.8/gems/mechanize-0.9.1/lib/www/mechanize/chain/handler.rb:6:in `handle'
from D:/Ruby/lib/ruby/gems/1.8/gems/mechanize-0.9.1/lib/www/mechanize/chain/pre_connect_hook.rb:14:in `handle'
from D:/Ruby/lib/ruby/gems/1.8/gems/mechanize-0.9.1/lib/www/mechanize/chain.rb:25:in `handle'
from D:/Ruby/lib/ruby/gems/1.8/gems/mechanize-0.9.1/lib/www/mechanize.rb:494:in `fetch_page'
from D:/Ruby/lib/ruby/gems/1.8/gems/mechanize-0.9.1/lib/www/mechanize.rb:545:in `fetch_page'
from D:/Ruby/lib/ruby/gems/1.8/gems/mechanize-0.9.1/lib/www/mechanize.rb:403:in `post_form'
from D:/Ruby/lib/ruby/gems/1.8/gems/mechanize-0.9.1/lib/www/mechanize.rb:322:in `post'
from test.rb:7

Answer 1

Just a guess, but does this help?

Answer 2

That page is most certainly UTF-8, however Mechanize uses NKF (a core Ruby library) to guess the encoding and for some reason it comes up as Shift JIS. The quickest way to work around the problem is to override the encoding mapping for Mechanize, so that when it attempts to convert the body to UTF-8 using Iconv it passes in the source encoding as UTF-8 as well. You can do it like this:

WWW::Mechanize::Util::CODE_DIC[:SJIS] = "UTF-8"

Place that just after the line where you require the Mechanize library. You may want to set the value back immediately after, or even better, find the root cause of the problem and submit a patch if necessary.

Note: The way I solved this was by debugging the Mechanize library by using the backtrace. The to_native_charset method calls detect_charset which is where the problem was.