parameter_sanitizer.rb

module Devise
  class ParametersSanitizer
    attr_reader :params
    def initialize(params)
      @params = params
    end

    def registration_params(mapping)
      params.require(mapping.name).permit(:email, :password, :password_confirmation)
    end

    def session_params(mapping)
      params.require(mapping.name).permit(*authentication_keys + [:password])
    end
    
    def unlock_params(mapping)
      # I have no idea of what unlocks need.
      params.require(mapping.name).permit([])
    end

    def password_params(mapping)
      params.require(mapping.name).permit(:email, :password, :password_confirmation, :reset_password_token)
    end
    
    protected
    def authentication_keys
      Devise.authentication_keys
    end
  end
end

class DeviseController
  def parameters_sanitizer
    DeviseController::ParametersSanitizer.new(params)
  end
end

module Devise
  class RegistrationsController
    def resource_params
      parameters_sanitizer.registration_params(devise_mapping)
    end
  end
end