Rails 5 token ActiveModel type

Rails 5 has a new ActiveModel type token. To define it you can use: has_scure_token.

So I had this class:

class Session < ApplicationRecord
  belongs_to :user

  before_validation(on: :create) do
    self.auth_token = SecureRandom.urlsafe_base64(24)
  end
end

And then I started to use the new has_secure_token and the code is way simpler now:

class Session < ApplicationRecord
  belongs_to :user
  has_secure_token :auth_token
end

If you use generators for models you can run:

rails generate model session auth_token:token

By the way the current implementation uses SecureRandom.base58(24), so it is url safe.