Could not find the source association(s) :followed_id in model relationship in Rails 3.2

Question

I get the following error message when requesting the home page of my sample app (following Michael Hartl's Tutorial chapter 11):

"ActiveRecord::HasManyThroughSourceAssociationNotFoundError in Pages#home"
"Could not find the source association(s) :followed_id in model Relationship. Try 'has_many :followed_users, :through => :relationships, :source => '. Is it one of :follower or :followed?"

This is really weird, since I followed the instructions of the tutorial exactly. I even copy pasted every single code fragment.

My user model (extract):

  class User < ActiveRecord::Base 

    has_many :relationships, foreign_key: "follower_id", dependent: :destroy
    has_many :followed_users, through: :relationships, source: "followed_id"

    has_many :reverse_relationships, foreign_key: "followed_id", class_name: "Relationship", dependent: :destroy
    has_many :followers, through: :reverse_relationships, source: :follower

My relationship model:

  class Relationship < ActiveRecord::Base
    attr_accessible :followed_id

    belongs_to :follower, class_name: "User"
    belongs_to :followed, class_name: "User"

    validates :follower_id, presence: true
    validates :followed_id, presence: true
  end

My migration file:

  class CreateRelationships < ActiveRecord::Migration
    def change
      create_table :relationships do |t|
        t.integer :follower_id
        t.integer :followed_id

        t.timestamps
      end

      add_index :relationships, :follower_id
      add_index :relationships, :followed_id
      add_index :relationships, [:follower_id, :followed_id], unique: true
    end
  end

I've been trying to fix this, but I simply don't have any idea left what the problem might be (exact code copy from the tutorial).

Answer 1

Found the error: In my user model I had to change

  has_many :followed_users, through: :relationships, source: "followed_id"  

to

  has_many :followed_users, through: :relationships, source: :followed  

Seems to be a typo in Hartl's tutorial Listing 11.10 http://ruby.railstutorial.org/book/ruby-on-rails-tutorial#code:has_many_following_through_relationships, since that's where I got the "source: "followed_id"" code from.

I got the fixed code from Hartl's github "sample app".