Rails application can be debugged with breakpoint library that allows you to top the flow of code execution and examine Ruby session. This examination allows you to expose local variables, modify them, and resume execution of your program. This is much better alternative to logging every step of the way with your log messaging.

In order to start debugging session with Rails you need to set breakpoints first and then start up your Rails server in debug mode via the following command line

> rails server –debbuger

Please note, breakpoints can be set anywhere within Ruby code including models, controllers, and helpers.  When your process hit the breakpoint, the irb session will start up your terminal.

Here is an example how you can set breakpoint in your code.

class Item < ActiveRecord::Base
 attr_accessor :title
 def title = (title)
  super
  breakpoint
 end
end

If your process hit breakpoint, it will stop processing your session and start up terminal with Ruby session running. This session allows you to look at all the local variable and methods. You can pass a name of the method to your breakpoints so you can see very descriptive message when debugging.