Cannot favorite users using polymorphic association - ruby-on-rails

Question

Using the system below users are able to favorite styles in the format of:
=> #<Favorite id: 59, user_id: 2, favoritable_id: 15, favoritable_type: "Style", created_at: "2013-04-06 08:47:08", updated_at: "2013-04-06 08:47:08">
I have built the system to enable users to favorite users as well, but for some reason the line Favorite.create!(:user => user) is not creating the expected favorite model object when called on User, as above when called on Style. Instead I am getting nils as below:
=> #<Favorite id: 65, user_id: 2, favoritable_id: nil, favoritable_type: nil, created_at: "2013-04-06 09:35:07", updated_at: "2013-04-06 09:35:07">
Problem is above. Details are below
Favorite Class:
class Favorite < ActiveRecord::Base
belongs_to :favoritable, :polymorphic => true
belongs_to :user
attr_accessible :user
validates_presence_of :user
validates_uniqueness_of :user_id, :scope => [:favoritable_type, :favoritable_id]
end
Model definitions including favoritable module (see below):
class User < ActiveRecord::Base
include Favoritable
class Style < ActiveRecord::Base
include Favoritable
Favoritable Module:
module Favoritable
extend ActiveSupport::Concern
included do
attr_accessible :favorites
has_many :favorites, :as => :favoritable, :autosave => true
accepts_nested_attributes_for :favorites
def add_favorite(user)
self.favorites << Favorite.create!(:user => user)
save
end
def delete_favorite(user)
self.favorites.where(:user_id => user.id).each do |favorite|
favorite.destroy
end
end
end
end
Favorites Controller:
class FavoritesController < ApplicationController
def fav_user
#user = User.find(params[:id])
#user.add_favorite(current_user)
respond_to do |format|
format.js { render :action => "update_favorite_disp", :layout => false }
end
end
def delete_fav_user
#user = User.find(params[:id])
respond_to do |format|
if #user.delete_favorite(current_user)
format.js { render :action => "update_favorite_disp", :layout => false }
end
end
end
def fav_style
#style = Style.find(params[:id])
#style.add_favorite(current_user)
respond_to do |format|
format.js { render :action => "update_favorite", :layout => false }
end
end
def delete_fav_style
#style = Style.find(params[:id])
respond_to do |format|
if #style.delete_favorite(current_user)
format.js { render :action => "update_favorite", :layout => false }
end
end
end
end

Answer 1

You need to pass in the :favoritable model in add_favorite:
def add_favorite(user)
Favorite.create!(:user =>user, :favoritable => self)
save
delete_favorite also needs to delete based on the :favoritable_id, instead of :user_id:
def delete_favorite(user)
user.favorites.where(:favoritable_id => self.id).each do |favorite|
favorite.destroy
end
end