No authentication headers when using Single Table Inheritance on my User model

[aaronshim]

Hello,
I have my user model set up as such

class User < ActiveRecord::Base
  devise :database_authenticatable, :registerable,
          :recoverable, :rememberable, :trackable, :validatable,
          :confirmable, :omniauthable
  include DeviseTokenAuth::Concerns::User

  ...

end

with SIngle Table Inheritance models set up as

class Applicant < User; end
class Judge < User; end
class Admin < User; end

and in my config/routes.rb

mount_devise_token_auth_for 'User', at: 'auth', controllers: { registrations: 'users/registrations' }

I want to use Single Table Inheritance because I intend to treat the main User model almost as an abstract class and have all accounts be either an Applicant, Judge, or Admin, where I can leverage polymorphism to define custom validations for each of the different types of accounts, etc. Yes, I've considered using a gem to take care of the roles, but since my roling is very primitive (always applicant, judge, or admin) and I would like to leverage inheritance, I thought a simple inheritance pattern was more fitting for the occasion.

Since all accounts will have a single sign-up and sign-in flow regardless of the type of account, I only mounted the devise routes for the superclass, rather than individually for each of the subclasses.

The problem arises when attempting to log on. The response body will come back properly, but the header will come back missing the uid, authentication-token, and client fields.

Stepping through the code in this gem, I believe the problem to be on this line:
https://github.com/lynndylanhurley/devise_token_auth/blob/master/app/controllers/devise_token_auth/concerns/set_user_by_token.rb#L50
By changing the line from

return @resource if @resource and @resource.class == rc

to

return @resource if @resource and @resource.is_a? rc

I was able to get my Single Table Inheritance user models to log in properly and respond with the correct headers.

My questions are:

1. Is this a valid fix? Is this change consistent with the intended behavior of this line of code?
2. If not, is there something in the configuration of devise_token_auth or the mounting of relevant routes that I could change to achieve this behavior?

Thank you for your help.

[rrooding]

This solved it for me as well, I hope someone can clear up if this is the way to go.

[zachfeldman]

Workaround posted, closing for now.