NameError - wrong constant name when creating user (Devise, Rails) - ruby-on-rails

Question

I'm using Rails 5.0.5 with Devise 4.3.0 for authentication. This app has been running smoothly for months, until I added a 'type'=>'string' attribute to my User model and attempted to create a new user. Submitting the form gives me a 500 internal server error. In this example, the User.type = 'hunter'.
NameError - wrong constant name hunter:
activesupport (5.0.5) lib/active_support/inflector/methods.rb:268:in `const_get'
activesupport (5.0.5) lib/active_support/inflector/methods.rb:268:in `block in constantize'
activesupport (5.0.5) lib/active_support/inflector/methods.rb:266:in `each'
activesupport (5.0.5) lib/active_support/inflector/methods.rb:266:in `inject'
activesupport (5.0.5) lib/active_support/inflector/methods.rb:266:in `constantize'
activesupport (5.0.5) lib/active_support/dependencies.rb:583:in `get'
activesupport (5.0.5) lib/active_support/dependencies.rb:614:in `constantize'
activerecord (5.0.5) lib/active_record/inheritance.rb:177:in `find_sti_class'
activerecord (5.0.5) lib/active_record/inheritance.rb:209:in `subclass_from_attributes'
activerecord (5.0.5) lib/active_record/inheritance.rb:55:in `new'
devise (4.3.0) lib/devise/models/registerable.rb:20:in `new_with_session'
app/models/user.rb:58:in `new_with_session'
user.rb:
def self.new_with_session(params, session)
if session['devise.user_attributes']
new(session['devise.user_attributes']) do |user|
user.attributes = params
user.valid?
end
else
super
end
end
Is Rails think this attribute value is a ClassName?? Can't seem to figure this one out. Any help greatly appreciated.

Answer 1

ActiveRecord uses the type column for Single Table Inheritance (STI) by default and the type value is expected to name a class. Presumably you don't have a hunter class so you get a confusing NameError from deep inside the guts of ActiveRecord.
From the fine manual:
inheritance_column()
Defines the name of the table column which will store the class name on single-table inheritance situations.
The default inheritance column name is type, which means it's a reserved word inside Active Record. To be able to use single-table inheritance with another column name, or to use the column type in your own model for something else, you can set inheritance_column:
self.inheritance_column = 'zoink'
Either rename your type column to something else or tell ActiveRecord to use some other column name for STI:
class User < ApplicationRecord
self.inheritance_column = 'there_is_no_sti_here' # Or whatever you're not using for a column name.
end
Using self.inheritance_column = nil also works.
If you're doing this a lot then you could make it declarative by adding a concern:
module STISuppression
extend ActiveSupport::Concern
included do
self.inheritance_column = nil
end
end
and then say things like:
class SomeModel < ApplicationRecord
include STISuppression
end
Same effect but it makes it clear what you're up to.