Favoriting System

project.rb

class Project < ActiveRecord::Base
  has_many :favorites, as: :favorited
  has_many :fans, through: :favorites, source: :user
end

# note: the key you use for the user has_many can really be anything you want. Try and use something that describes what the
# assocation is, though.
#
# You can now do the following in order to retrieve the users who have favorited a particular project.
#
# project = Project.first
# project.fans #=> #<ActiveRecord::Associations::CollectionProxy [#<User id:...]>
#
# You can then loop through each of the users like so
#
# project.fans.each do |user|
#   puts user.name
# end

You can also return the number of times a project has been added to favorites:

project = Project.first
project.favorites.count

This number reflects all associations that have the ability to favorite a project. If you only want the number of times the project has been favorited by a user object, you can do this instead:

project = Project.first
project.fans.count