Where to add query methods?

query_methods.rb

# 1
List.fetch_by_slug(@site, 'mys-slug')
    
# 2 - adding query methods on the collection
@site.lists.fetch_by_slug('my-slug')

# How achieved
class Site < ActiveRecord::Base
  has_many :lists do
    def fetch_by_slug(slug)
      includes(:rows).where(slug: slug)
    end
  end
end
    
# 3 - query methods on the parent
@site.fetch_list_by_slug('my-slug')