Relationship like Twitter followers/followed in ActiveRecord

I'm trying to represent a relationship between users 开发者_Go百科in my application where a user can have many followers and can follow other users. I would like to have something like user.followers() and user.followed_by() Could you please tell me in details how to represent this using ActiveRecord?

Thanks.

You need two models, a Person and a Followings

rails generate model Person name:string
rails generate model Followings person_id:integer follower_id:integer blocked:boolean

and the following code in the models

class Person < ActiveRecord::Base
  has_many :followers, :class_name => 'Followings', :foreign_key => 'person_id'
  has_many :following, :class_name => 'Followings', :foreign_key => 'follower_id' 
end

and corresponding in the Followings class you write

class Followings < ActiveRecord::Base
  belongs_to :person
  belongs_to :follower, :class_name => 'Person'
end

You could make the names clearer to your liking (i especially don't like the Followings-name), but this should get you started.

The twitter follower model differs from the friendship model in that you do not need permission from the person to follow them. Here I set up a lazy loading where the relationship is not fully defined in the person object.

/app/models/person.rb

  def followers
    Followership.where(:leader_id=>self.id).not_blocked
  end

  def following
    Followership.where(:follower_id=>:self.id).not_blocked
  end
  has_many :followers, :class_name=>'Followership'
  has_many :followed_by, :class_name=>'Followership'

/app/models/followership.rb

  belongs_to :leader, :class_name=>'Person'
  belongs_to :follower, :class_name=>'Person'

  #leader_id integer
  #follower_id integer
  #blocked boolean

  scope :not_blocked, :conditions => ['blocked = ?', false]