POST request capture with Mechanize

I'm trying to use Mechanize to capture a POST request which is not possible via a form, because the form is inside an iframe that prevents loading directly via javascript.

The HTTP Headers are the following in an example request from Google Chrome (notice the parada and linea parameters)

Request URL:http://www.etr.gov.ar/getSmsResponse.php
Request Method:POST
Status Code:200 OK
Request Headers
Accept:*/*
Accept-Charset:ISO-8859-1,utf-8;q=0.7,*;q=0.3
Accept-Encoding:gzip,deflate,sdch
Accept-Language:es-419,es;q=0.8
Connection:keep-alive
Content-Length:21
Content-Type:application/x-www-form-urlencoded
Host:www.etr.gov.ar
Origin:http://www.etr.gov.ar
Referer:http://www.etr.gov.ar/cont-cuandollega.php
User-Agent:Mozilla/5.0 (X11; Linux i686) AppleWebKit/534.30 (KHTML, like Gecko) Chrome/12.0.742.30 Safari/534.30
X-Requested-With:XMLHttpRequest

Form Dataview URL
parada:4152
linea:112

Response Headers
Connection:close
Content-Length:111
Content-Type:text/html
Date:Fri, 03 Jun 2011 02:35:45 GMT
Server:Microsoft-IIS/7.5
X-Powered-By:PHP/5.1.2
ASP.NETl

And the content for this example is:

Linea 112N: 0min. 379mts., siguiente 25min. 9937mts. - Linea 112R: 81min. 24349mts., siguiente 101min. 30548mts

What I've tried with mechan开发者_JS百科ize is the following ruby script, but I get a blank page in response:

require 'mechanize'
agent = WWW::Mechanize.new
agent.post("http://www.etr.gov.ar/getSmsResponse.php", "parada" => "4152", "linea"=>"112")

What could I'd be doing wrong? Thank you very much.

UPDATE: Passing the POST as a hash worked perfectly. To render the content then I only had to do agent.post.content

Actually, your original code worked fine. You just need to print it out as agent.post.content to see the results.

To respond to mightilybix's answer:

The reason your code works without passing a hash using { and } is because Ruby has a feature where if you pass a hash as the last argument of a function then you don't need to include braces. For example:

def test(str, params)
  puts str
  params.each { |param| puts param }
end

Calling:

test("hello", {"animal" => "cat", "gender" => "m"})

is the exact same thing as calling:

test("hello", "animal" => "cat", "gender" => "m")

The post method expects the parameters as a hash. Try:

agent.post("http://www.etr.gov.ar/getSmsResponse.php", {"parada" => "4152", "linea"=>"112"})