A few things to note when trying to process an uploaded file with paperclip:

• The only way a post-processor will run is if a style is defined

class MyModel < ActiveRecord::Base

has_attached_file :mp3, :url => '/:class/:id/:style.:extension', :path => ':rails_root/assets/:class/:id_partition/:style.:extension', :whiny => true, :styles => { :text => { :do_something => true } }, :processors => [:my_processor]

# ...

end

• To access the file after processing but before paperclip is finished, use the :after_process callback -- model instance attributes can be modified and will be saved automatically as part of the paperclip process

class MyModel < ActiveRecord::Base

# ...

after_post_process :do_one_more_thing

# ...

private

def do_one_more_thing

logger.info "MyModel [paperclip] after_post_process"

logger.info "MyModel [paperclip] file #{mp3.queued_for_write[:original].path}"

# Do more with the file

# Make model attribute changes as needed

# self.my_attribute = "x"

end

end

• View paperclip documentation at http://dev.thoughtbot.com/paperclip/