casey_redis.rb

# config/initializers/redis.rb
require 'rubygems'
require 'redis'

REDIS = Redis.new()

class User
  attr_accessor :name, :id

  def initialize(name, id)
    @name = name
    @id = id
  end

  def like_recipe(recipe)
    REDIS.sadd "user:#{self.id}:liked_recipes", recipe.id
  end

  def has_in_common_with_user?(another_user)
    REDIS.sinter("user:#{self.id}:liked_recipes", "user:#{another_user.id}:liked_recipes").size > 0
  end

  def liked_recipes
    REDIS.smembers "user:#{self.id}:liked_recipes"
  end
end


class Recipe
  attr_accessor :name, :id, :stuff_in_in

  def initialize(name, id, stuff_in_it = [])
    @name = name
    @id = id
    @stuff_in_it = []
  end
end

r1 = Recipe.new("Spaghetti", 1, ["tomato", "onion", "meat"])
r2 = Recipe.new("Pizza", 2, ["tomato", "onion", "flour"])

u1 = User.new("elad", 1)
u2 = User.new("casey", 2)

u1.like_recipe(r1)
u1.like_recipe(r2)
u2.like_recipe(r2)

puts "user #{u1.name} likes: #{u1.liked_recipes}"
puts "user #{u2.name} likes: #{u2.liked_recipes}"

puts "#{u1.name} has recipes in common with #{u2.name}: #{u1.has_in_common_with_user?(u2)}"