Answers for "self referencing association in ruby on rails"

rails self relation

class MyModel < ActiveRecord::Base
  belongs_to :parent, :class_name => 'MyModel'
  has_many :children, :class_name => 'MyModel', :foreign_key => 'parent_id'
end

self referencing association in ruby on rails

has_many :users, class_name: 'User'
belongs_to :manager, class_name: 'User', optional: true