ActsRateable is a Rails 3 ruby gem designed to enable bi-directional polymorphic rating - users rate companies, companies rate users. It records individual rates and caches ratings, enable quick ordering of resources by rating.
The cached ratings contain four different points of data:
:total => rate count
:average => rate average
:sum => rate sum
:estimate => rate estimate
The estimate is probably the most useful of the data points, as it provides a weighted score based on the number of times the resource has been rated.
To determine this estimate, the gem calculates a bayesian estimate, as inspired by IMDB's top 250 list.
The formula for calculating the Top Rated 250 Titles gives a true Bayesian estimate:
weighted rating (WR) = (v ÷ (v+m)) × R + (m ÷ (v+m)) × C
Where:
R = average for the movie (mean) = (Rating) v = number of votes for the movie = (votes) m = minimum votes required to be listed in the Top 250 C = the mean vote across the whole report (currently 7.1)
* R = average rating for resource
* v = number of ratings for resource
* m = average number of votes
* C = average rating of all resources
-
Include the gem in your rails project gem file.
gem 'acts_rateable' -
Run:
bundle install rails generate acts_rateable rake db:migrate -
Add
acts_rateableto the models you wish to have the ability to rate or be rated.
To rate a resource:
author.rate( resource, value )
For example,
current_user.rate( post, 5 )
To test whether a resource has been rated an author:
post.rated_by?( author )
The rate will be returned if the user has rated the resource, otherwise an empty set of ratings is returned.
You may want to test it like this to get a true/false:
post.rated_by?( author ).empty?
To test whether an author has rated a resource:
current_user.has_rated?( post )
The rate will be returned in the user has rated the resource, otherwise false will be returned.
To get the rating for a resource:
post.rating
Four types of data are cached for every resource rated:
:total => rate count
:average => rate average
:sum => rate sum
:estimate => rate estimate
For example:
post.rating( :total )
Will return the rate count.
post.rating( :average )
Will return the rate average.
post.rating( :sum )
Will return the rate sum.
post.rating( :estimate )
Will return the rate estimate.
To find out how close or far off the author was in their rating from the resource estimate:
post.variation(author)
Will return a percentage of deviation.
Any rateable resource may be ordered by any of the four cached data points, in either direction: DESC, ASC.
For example:
Post.order_by_rating(:estimate, 'DESC')
Will return all posts ordered by estimate in descending order.
For issues, problems or bugs, please post an issue, here:
https://github.com/tyrauber/acts_rateable/issues
For future development:
- fork the repository
- extend the functionality
- issue pull request