What is the correct order of associations, scopes, validations, etc. in Rails models

Question

Edited this old question to include an answer from below: Rubocop has it https://github.com/rubocop-hq/rails-style-guide#macro-style-methods

Rails is all about 'Convention over Configuration'. However, I haven't come across a 'standard' for the order of associations, scopes, includes, validations, ... in Rails models yet. Take for example the following, simplified, product model:

class Product < ActiveRecord::Base
  mount_uploader :logo, AssetUploader
  acts_as_taggable
  paginates_per 50

  include ActionView::Helpers::NumberHelper

  belongs_to :company

  validates_presence_of [:title, :price, :plu]

  scope :on_website, where(display: true)

  def display_price
    ...
  end
end

Is this the correct order? It's maybe not that important to many people, but I personally think it would be great if there were a convention on this.

Answer 1

There is no such convention. But you can create one for your project and be consistent with it in all the models. This is what i follow.

class Model < ActiveRecord::Base
   #all mixins
   include Something
   extend Something

   #other stuff
   acts_as_taggable
   paginates

   #associations
   has_many :something
   belongs_to :something_else

   #validations
   validate_presence_of :something

   #scopes
   scope :something

   #instance methods
   def instance_method
   end

   #class methods
   def self.method
   end

   #private methods
   private
   def method2
   end
end