Debug after a POST request

I'd like to debug my app step-by-step to see what happens AFTER the form submission (only via POST).

The problem is the URL after submission is the same than the one before, and I do not know any way to t开发者_开发技巧ell the debugger to wait for the submission of the form...

Any ideas ? Thanks in advance !

Take a look at the Guides of Ruby on Rails, there is a description how to debug rails:

http://guides.rubyonrails.org/debugging_rails_applications.html#debugging-with-ruby-debug