Stupid-simple invitations with Devise

admin.rb

class Admin < ActiveRecord::Base
  attr_accessor :invite

  devise :database_authenticatable, :registerable, :recoverable, :rememberable,
    :trackable, :validatable

  def self.new_invited(attributes)
    new(attributes.merge(invite: true))
  end

  private

  # Slightly modified version of
  # Devise::Modules::Recoverable#send_reset_password_instructions that doesn't
  # save the record (since we call this method right before a save) and allows
  # us to trigger our own special invite mailer
  def invite!
    generate_reset_password_token if should_generate_reset_token?
    # TODO: Invoke invite mailer here instead of reset password mailer
    devise_mailer.reset_password_instructions(self).deliver
  end

  # Overrides Devise::Modules::Recoverable#password_required? so that #password
  # isn't required when we're inviting a user.
  def password_required?
    invite ? false : super
  end
end