How do I use a before_action type callback with ActiveModel::Model?

Question

I have a database model that doesn't actually have any data since all my User information is stored on a third party authentication service. I want to be able to use the Model like a regular one, so upon load, I fetch all the information from the API and store it in an instance variable.

How do I setup a before_action like callback for my model? Is there a Ruby way to do this?

class Auth0User < ApplicationRecord
  before_action set_instance_variables

  validates :auth0_id, presence: true,
                       uniqueness: true

  def info(key = nil)
    key.nil? ? @user : @user[key.to_s]
  end

  private

  def set_instance_variables
    @user ||= auth0_api.user auth0_id
  end

  def auth0_api
    Auth0Client.new(
      client_id: Rails.application.secrets.auth0_client_id,
      token: Rails.application.secrets.auth0_management_jwt,
      domain: Rails.application.secrets.auth0_domain,
      api_version: 2
    )
  end
end

Answer 1

after_intialize完全符合我的需要。

Answer 2

Yes, and actually rails had a lot of methods for you to choose:

• before_save
• before_create
• before_destroy

You can check here for more methods: http://guides.rubyonrails.org/active_record_callbacks.html