Embedded association not being persisted - ruby-on-rails

Question

I've followed this tutorial for the exact same use case of assigning roles to users.
I'm using Rails 3.2.16.
When I try testing role assignment from the pry console I get that the roles field of User is not updated.
here's the pry text:
[14] pry(main)> a = User.last
User Load (0.3ms) SELECT `users`.* FROM `users` ORDER BY `users`.`id` DESC LIMIT 1
=> #<User id: 7, email: "a#b.c", encrypted_password: "...", reset_password_token: nil, reset_password_sent_at: nil, remember_created_at: nil, sign_in_count: 1, current_sign_in_at: "2013-12-29 11:14:36", last_sign_in_at: "2013-12-29 11:14:36", current_sign_in_ip: "127.0.0.1", last_sign_in_ip: "127.0.0.1", created_at: "2013-12-29 11:14:04", updated_at: "2013-12-31 09:50:26", username: "asf", confirmation_token: nil, confirmed_at: "2013-12-29 11:14:26", confirmation_sent_at: "2013-12-29 11:14:04", unconfirmed_email: nil, roles_mask: 0>
[15] pry(main)> a.roles = [:admin, :expired]
=> [:admin, :expired]
[16] pry(main)> a.save
(0.1ms) BEGIN
(0.1ms) COMMIT
=> true
Here's the relating methods from the model:
ROLES = %w[admin active expired]
def roles=(roles)
self.roles_mask = (roles & ROLES).map { |r| 2**ROLES.index(r) }.sum
end
def roles
ROLES.reject { |r| ((roles_mask || 0) & 2**ROLES.index(r)).zero? }
end
def role_symbols
roles.map(&:to_sym)
end
and here's the migration:
class AddRolesMaskToUsers < ActiveRecord::Migration
def change
add_column :users, :roles_mask, :integer
end
end
Would you know why the association is not persisted here?
thanks a lot in advance.

Answer 1

I figured that I was matching strings with symbols in the roles= method and this would not work.
I've converted everything to symbols now, and it works nicely.
Here's the new code:
ROLES = [:admin, :active, :expired]
def roles=(roles)
self.roles_mask= (roles & ROLES).map { |r| 2**ROLES.index(r) }.sum
end
def roles
roles_symbols.reject { |r| ((roles_mask || 0) & 2**ROLES.index(r)).zero? }
end