Ruby - :: in class name
class Parsers::AdfParser is in practice equivalent to:
module Parsers class AdfParserFor this to work properly, and the file to be autoloaded its location should be parsers/adf_parser.rb, whether under app/models or lib. Basically the file path needs to mimic the class hierarchy.
It's in the parsers sub-directory of modules; Rails namespaces for you by convention.