Rails extending ActiveRecord::Base

Question

I\'ve done some reading about how to extend ActiveRecord:Base class so my models would have some special methods. What is the easy way to extend it (step by step tutorial)?<

Answer 1

With Rails 5, all models are inherited from ApplicationRecord & it gives nice way to include or extend other extension libraries.

# app/models/concerns/special_methods.rb
module SpecialMethods
  extend ActiveSupport::Concern

  scope :this_month, -> { 
    where("date_trunc('month',created_at) = date_trunc('month',now())")
  }

  def foo
    # Code
  end
end

Suppose the special methods module needs to be available across all models, include it in application_record.rb file. If we wants to apply this for a particular set of models, then include it in the respective model classes.

# app/models/application_record.rb
class ApplicationRecord < ActiveRecord::Base
  self.abstract_class = true
  include SpecialMethods
end

# app/models/user.rb
class User < ApplicationRecord
  include SpecialMethods

  # Code
end

If you want to have the methods defined in the module as class methods, extend the module to ApplicationRecord.

# app/models/application_record.rb
class ApplicationRecord < ActiveRecord::Base
  self.abstract_class = true
  extend SpecialMethods
end

Hope it help others !