Debugging Rails Demo (5 Minutes)


This demo shows the features of the Rails debugger in NetBeans.

Product Versions Supported

NetBeans 6.0 M10

Points to Hit

  • You can't do this shit with TextMate bro'

Demo Prep

  1. This demo is a follow-on to the Agile Development Of The Plugin Portal demo, so complete that demo first.
  2. Select Tools > Options > Misc > Ruby and select the Fast Debugger (ruby-debug-ide). NetBeans automatically download the gem for you.


  • The IDE sometimes throws a NPE trying to set a breakpoint. If this happens, delete your userdir and try again.
  • Be careful with Step Into, because the Step Out rarely returns me from where I came. When this happens, I just continue (Ctrl+F5) and repeat the cycle.


  • Show the options and how the Fast Debugger should be enabled. Explain that using the Classic built-in debugger is unbearable. Work on the Fast Debugger is in progress for JRuby, but it's not there yet.
  • Set a breakpoint at line 1 of show.rhtml (yes, we can even degug RHTML files).
  • Stop the server if it is running and Debug the project.
  • Switch to the browser and click the show link.
  • Switch to NetBeans and view the local variables under 'self'. It's a great way to see all that is provided for you by the framework: @flash @params, @request, @response, @session, @url to name just a few.
  • Look at the @params to see the action, id and controller called.
  • Step into Plugin.content_columns method. This is a cool ActiveRecord feature that aims to return an array of columns that only contain content, i.e., no ids.
  • Step Out back into the Show.rhtml.
  • Continue pressing Step Into until you are in column.human_name. This is another cool ActiveRecord feature that attempts to return the human readable name of a database column name.
  • Step Out.
  • Hover your mouse over the to see its value as a tool tip.
  • Press Continue until the Show page appears.

Next Steps

Plugin Portal With Java Demo

Demo Cleanup

These are the necessary steps to take in order to successfully run the demo again on the same machine.

  • None
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