Ruby Mechanize login not working

Let me set the stage for what I'm trying to accomplish. In a physics class I'm taking, my teacher always likes to brag about how impossible it is to cheat in her class, because all of her assignments are done throu开发者_StackOverflow社区gh WebAssign. The way WebAssign works is this: Everyone gets the same questions, but the numbers used in the question are random variables, so each student has different numbers, thus a different answer. So I've been writing ruby scripts to solve the question's for people by just imputing your specific numbers.

I would like to automate this process using mechanize. I've used mechanize plenty of times before, but I'm having trouble logging in to the site. I'll submit the form and it returns the same page I was just on. You can take a look at the site's source code, at http://webassign.net, and I've also tried using the login at http://webassign.net/login.html with no luck either.

Let me follow all of this up with some ruby code that doesn't do what I want it to:

require 'rubygems'
require 'mechanize'

agent = Mechanize.new

page = agent.get("http://www.webassign.net/login.html")
form = page.forms.last
puts "Enter your username"
form.WebAssignUsername = gets.chomp
puts "Enter your password (Don't worry, we don't save this)"
form.WebAssignPassword = gets.chomp
form.WebAssignInstitution = "trinityvalley.tx"

form.submit #=> Returns original page 

If anyone really takes an interest in getting this to work, I would be more than happy to send them a working username and password.

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The site could be checking that the Login post variable is set (see the login button). Try adding form.Login = "Login".

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Have you tried to use agent.submit(form, form.buttons.first) instead of form.submit?

This worked for me when I tried to submit a form. I tried using form.submit first and it kept returning the original page.

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Try setting the user agent:

agent = Mechanize.new do |a|
  a.user_agent_alias = 'Mac Safari'
end

Some sites seem to require that.

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Your question seems a little ambiguous, saying that you're not having any luck? What is the problem exactly? Are you getting a different response entirely than when you view the page in a browser? If so, then do what @cam says and analyzer the headers, you can do it in Firefox via an extension, or you can do it in Chrome natively. Either way, try to mimic the headers that you see in whatever browser you are doing in you mechanize user agent. Here is a script that I used to mimic the iTunes request headers when I was data-mining the app-store:

def mimic_itunes( mech_agent )
  mech_agent.pre_connect_hooks << lambda {|headers|
    headers[:request]['X-Apple-Store-Front'] = X_APPLE_STOREFRONT;
    headers[:request]['X-Apple-Tz'] = X_APPLE_TZ;
    headers[:request]['X-Apple-Validation'] = X_APPLE_VALIDATION;  
  }
  mech_agent.user_agent = 'iTunes/9.1.1 (Windows; Microsoft Windows 7 x64 Business Edition (Build 7600)) AppleWebKit/531.22.7'
  mech_agent
end

Note: the constants in the example are just strings... not really that important what they are, as long as you know you can add any string there

Using this approach, you should be able to alter/add any headers that the web application might need.

If this is not the problem that you are having, then post more in-depth details of what exactly is happening.