ActiveRecord Virtual Attributes treaded as a record attributes

Question

I am running into a problem with to_json not rendering my virtual attributes

class Location < ActiveRecord::Base
    belongs_to :event
    before_create :g         


        

Answer 1

An old question but what OP asked is now possible and simple once you know how. Here a complete runnable example but everything you need is in the class Location. The attribute statement expands the attributes of the model and the after_initialize takes care of the assignment of the value.

require 'active_record'  

ActiveRecord::Base.establish_connection(  
  :adapter=> "sqlite3",  
  :database=> ":memory:"  
)  

ActiveRecord::Schema.define do
  create_table :events do |table|
    table.column :name, :string
  end
  create_table :locations do |table|
    table.column :name, :string
    table.column :event_id, :integer
  end
end

class Event < ActiveRecord::Base
  has_one :location
end

class Location < ActiveRecord::Base
  belongs_to :event
  attribute :event_name, :string

  after_initialize do
    self.event_name = event.name
  end
end

Event.create(name: 'Event1')
Location.create(name: 'Location1', event_id: 1)
p Model.attribute_names
p Event.first
p Event.first.location

#["id", "name", "event_id", "event_name"]
#
#