ActsAsMongoRateable (with weights!)

Inspired by the old Rails+AR standby "acts_as_rateable," this rating plugin works with MongoDB+MongoMapper and has weighted ratings, as well as bayesian and straight averages, and some friendly class-level helpers.

Intends to be super-performant by taking advantage of the benefits of document-driven db denormalization.

Requirements

MongoDB
MongoMapper gem
Expects you to have a User model that includes MongoMapper::Document

Installation

Install the plugin:

./script/plugin install git://github.com/mepatterson/acts_as_mongo_rateable.git

Add the following 2 lines to the Model class that you want to make rateable:

include ActsAsMongoRateable
RATING_RANGE = (1..5)

Obviously, change the rating range if you want to rate on a 10-star system or a 14-star or whatever.

Usage

class User
  include MongoMapper::Document
end

class Widget
  include ActsAsMongoRateable
  RATING_RANGE = (1..5)
  include MongoMapper::Document
end

widget = Widget.first

To rate it:

widget.rate(score, user, weight)

score must be an Integer within your RATING_RANGE
user is the User who is rating this widget
weight is optional; defaults to 1)

Now try all these fun methods:

widget.average_rating

widget.bayesian_rating

widget.rating_stats

And some useful class methods:

Widget.highest_rated(how_many)

Widget.most_rated(how_many)

Widget.most_rated_by_authorities(how_many)

Widget.highest_bayesian_rated(how_many)

('how_many' is a limit and is optional. i.e. Do you want a highest_rated list of 5, 10, 15 widgets?
Defaults to just 1 if you don't pass any argument.)

Future

Tests (I have tests in the project I cut this from, but they need to be extracted out and I'm lazy)
More helper methods
Performance improvements as I come across the need
Investigate using map/reduce to improve the efficiency of the bayesian calc (?)

Thanks To...

John Nunemaker and the rest of the folks on the MongoMapper Google Group
The MongoDB peoples and the MongoDB Google Group
juixe for the original acts_as_rateable plugin for ActiveRecord
sunlightlabs 'datacatalog-api', from which I borrowed the ratings_stats hash methodology