Debugging Rails

I've just had a painful experience: Rails does not accept an HTTP request from facebook canvas, and all it returns is HTTP 422 status, which practically means nothing.

After googling for a while, I have found a way to debug a rails server. Simply, runs

ruby script/server

and that is it. You will see debugging message from Rails on the terminal.

And another good thing about it is that you do not need to restart the server everytime you make a change.