Maintaining different formats of an attribute for an ActiveRecord model

main.rb

# db/schema
create_table "product_versions", force: true do |t|
  t.string   "string"
  t.text     "changelog_as_markdown"
  t.text     "changelog_as_html" # OPTIONAL - used for caching in Options 2 & 3 below
end

# Option 1: calculate HTML version of the changelog on-the-fly
class ProductVersion < ActiveRecord::Base
  def changelog_as_html
    if changelog_as_markdown.present?
      markdown.parse(changelog_as_markdown)
    end
  end
end

# Option 2: override Markdown setter to also set HTML
class ProductVersion < ActiveRecord::Base
  def changelog_as_markdown=(value)
    super
    if changelog_as_markdown.present?
      self.changelog_as_html = markdown.parse(changelog_as_markdown)
    end
  end
end

# Option 3: persist HTML changelog to the database using callbacks
class ProductVersion < ActiveRecord::Base
  before_save :set_changelog_as_html
  
  private
  
  def set_changelog_as_html
    if changelog_as_markdown.present?
      self.changelog_as_html = markdown.parse(changelog_as_markdown)
    end
  end
end