Parsing JSON -> Ruby in Rails?

Charlie Hubbard wrote:

If I'm not supposed to use json library, then what does rails provide
out of the box for going from json -> ruby?

I can't find anything currently built-in, but I've been successfully
using SafeJSON.rb (put it in the lib directory):

http://www.xerial.org/projects/Xerial/browser/ruby/trunk/aqua/mixi/SafeJSON.rb?format=txt