You are using Devise in your rails application, and you want to have a token for authenticating an API call, but you don’t want to use the default authentication token so that.
The purpose of doing something like that is that you don’t want the application to have the same authentication rights as the devise authentication tokens.
Add the field to your user model (ie app_token).
On your user model create the following:
class User < ActiveRecord::Base
self.app_token = Devise.friendly_token