Struct Objects with ActiveRecord methods? (Ruby on Rails)

Question

I have a limited set of objects (20 - 30) which I need to be able to combine with ActiveRecord Objects. Putting them into the DB just seems awful because I already have two other join models hooked up to the model.

So let's say i have a class

class Thing < ActiveRecord::Base
  has_many :other_things, :class_name => 'OtherThing'
end

with an existing table. How would I be able to combine this with a class not inheriting from ActiveRecord (here's my best guess)

class OtherThing < ActiveRecord::Base
  OtherThing = Struct.new(:id, :name, :age, :monkey_fighting_ability)
  belongs_to :thing, :class_name => 'Thing'

  validate :something

  def self.search_for(something)
    MY_GLOBAL_HASH[something].map do |hash|
      instance = OtherThing.new
      hash.each_pair do |k,v|
        instance.send(:"#{k}=", v)
      end
      instance
    end
  end

  #if AR wants to call save
  def save
    return true
  end
  alias save save!

  protected
    def something
      self.errors.add(:monkey_fighting_ability, 'must be unlimited') if self.class.search_for(something).empty?
    end
end

Point being that I want to use ActiveRecord methods and so on without ever hitting the db. Help is greatly appreciated.

Mike Lewis · Accepted Answer · 2011-03-21 19:29:51Z

3

I'd suggest reading the post on "Make any Ruby Object Feel Like An Active Record" by Yehuda Katz. It goes over how to convert any object into a model-like class, without the database backing.

Good Luck!

answered Mar 21, 2011 at 19:29

Mike Lewis

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2 Comments

Mike Lewis Over a year ago

I did actually. It works great for not only the case that you have, but also for validations of any object. Taking advantage of AR validations is amazing.

Beat Richartz Over a year ago

Sounds intriguing. Thanks again!

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