Rails: Friendship join table clarification - ruby-on-rails

Question

I'm currently working on my first project and am trying to add "friending" to my app. However, I'm having a little trouble grasping the concept of the friendships model, since attributes that don't seem to exist in my database seem to just work.
I have my model and database columns listed below. I understand that this is a join table, but in the user model where do friends, requested_friends, and pending friends come from if they don't exist in the friendships table? Is it because it is a virtual join table so that I could just add whatever columns I need without having to migrate them?
Also, the tutorial eventually does #user.pending_friends.each even though that column doesn't exist in my users table. I'm pretty confused on this part.
Currently I'm going through this brief tutorial: http://railsforum.com/viewtopic.php?id=16760
Here are my files:
user model
class User < ActiveRecord::Base
...
...
has_many :friendships, :dependent => :destroy
has_many :friends, :through => :friendships, :conditions => "status = 'accepted'"
has_many :requested_friends, :through => :friendships, :source => :friend, :conditions => "status = 'requested'", :order => :created_at
has_many :pending_friends, :through => :friendships, :source => :friend, :conditions => "status = 'pending", :order => :created_at
end
friendship model
class Friendship < ActiveRecord::Base
attr_accessible :friend_id
belongs_to :user
belongs_to :friend, :class_name => "User"
end
schema
create_table "friendships", :force => true do |t|
t.integer "user_id"
t.integer "friend_id"
t.datetime "created_at", :null => false
t.datetime "updated_at", :null => false
end
create_table "users", :force => true do |t|
t.string "name"
t.string "email"
t.datetime "created_at", :null => false
t.datetime "updated_at", :null => false
t.string "password_digest"
t.string "remember_token"
end

Answer 1

You probably forgotten to migrate since you don't have status column in your schema. Associations you're referring is bound to friend_id key that exist in friendships table. Last 2 associations is just using foreign key defined for belongs_to :friend. Please have a look here. I guess such associations can work without actual attribute if this is what you meant, you just don't get condition: functionality here and all 3 last associations will return same values.