<h3>ActsAsFollowed</h3>
<h3>===============</h3>

<strong>Revised, April 14th.</strong> 

I've made some changes to how this works so that followships can work as a two-way street: i.e. followers *and* followeds are both polymorphic.  In doing so, I changed the name of the associations, so that if you are acts_as_followed, your association proxy is named *followerships* and if you are acts_as_follower, your association proxy is named *followeeships*. This allows two users to follow each other without a namespace clash on the association proxy (previously, both were "followships", so you couldn't follow each other).  In other words, I broke the way it was before. Also, the migration has changed to add *follower_type*. 

<h3>Description</h3>

ActsAsFollowed sets up a polymorphic association between different models in order to track users (or resources) who are "following" a certain resource. You can use this to trigger events such as email notifications, etc. So, if a user is following a Project, or a Comment, or another User, you can create an observer that sends emails based on followships during the lifecycle (create, update, whatever) of the resource they are following.

<h3>Migration</h3>
# Create this table in your migrations
class CreateTableFollowships < ActiveRecord::Migration
  def self.up
   create_table "followships", :force => true do |t|     
     t.integer  "followed_id"
     t.string   "followed_type"
     t.integer  "follower_id"  
     t.string   "follower_type"  
     t.timestamps
    end
  end

  def self.down
    drop_table :followships
  end
end


<h3>Examples</h3>

<h4>One</h4>
A model can be *acts_as_followed*, *acts_as_follower*, or both. 

Since the Internet was invented so that we can have a reliable, 24-hour cat-channel, let's use our favorite feline to demonstrate:

class Lion
  acts_as_followed
end

class HouseCat
  acts_as_followed
  acts_as_follower
end

So, if you have two house-cats, Lucy and Flora, who admire each other:

lucy  = HouseCat.new
flora = HouseCat.new

You can add a followership to each of them, referencing the other

lucy.start_following!(flora)
flora.start_following!(lucy)

And, voila, a reciprocal relationship of feline adoration, resulting in a lot of tail-chasing: 

lucy.following?(flora) => true
flora.following?(lucy) => true

If lucy also reads her C.S. Lewis, she may have another hero:

aslan = Lion.new
lucy.start_following!(aslan)
lucy.following?(aslan) => true

In this case, aslan cannot follow lucy because aslan is acts_as_followed, but not acts_as_follower. 

<h4>Two</h4>
This can also be used for non-cat (non person-to-person) followships. For instance, a user can follow a Comment, Project, Event, etc -- anything that you want to give updates on. The updates aren't a part of this plugin, you handle those depending on your needs. Simple Example 

class Discussion
  acts_as_followed
end

class User
 acts_as_follower
end

user = User.new
discussion = Discussion.new

user.start_following!(discussion)
discussion.followerships => [user.followeeships.first] # all of the followeeships for this discussion
user.followeeships => [discussion.followerships.first] # all of the followerships for this user

<h4>Methods</h4>

Given a Follower and a Celebrity (whichever classes you like)
follower  = User.first
celebrity = Celebrity.first

*acts_as_follower*

  start_following!
    follower.start_following!(celebrity)
  
  following?
    follower.following?(celebrity) => true

  followeeships
    followed.followeeships => [] # all followeeships 

  followeeships.for(celebrity)
      followed.followeeships => [] # the array of the followeeships for that resource. (*Note* will add uniqueness scoping so it can only be one item long)
  
  
*acts_as_followed*

  celebrity.followerships.for(celebrity) => followship for the particular resource


<h3>Next things I want to add</h3>
  * Uniqueness scoping on followships
  * More convenience methods for accessing the person/thing you are following/being followed by
  
  
Copyright (c) 2009 [Sarah Gray], released under the MIT license