Rails Associations has_one Latest Record

Question

I have the following model:

class Section < ActiveRecord::Base
  belongs_to :page
  has_many :revisions, :class_name => 'SectionRevision', :foreign_key => 'section_id'
  has_many :references

  has_many :revisions, :class_name => 'SectionRevision', 
                       :foreign_key => 'section_id'

  delegate :position, to: :current_revision

  def current_revision
    self.revisions.order('created_at DESC').first
  end
end

Where current_revision is the most recently created revision. Is it possible to turn current_revision into an association so I can perform query like Section.where("current_revision.parent_section_id = '1'")? Or should I add a current_revision column to my database instead of trying to create it virtually or through associations?

Answer 1

To get the last on a has_many, you would want to do something similar to @jvnill, except add a scope with an ordering to the association:

has_one :current_revision, -> { order created_at: :desc }, 
  class_name: 'SectionRevision', foreign_key: :section_id

This will ensure you get the most recent revision from the database.