287 lines
5.8 KiB
Markdown
287 lines
5.8 KiB
Markdown
# Rating
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[](https://travis-ci.org/wbotelhos/rating)
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[](https://badge.fury.io/rb/rating)
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A true Bayesian rating system with scope and cache enabled.
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## JS Rating?
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This is **Raty**: https://github.com/wbotelhos/raty :star2:
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## Description
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Rating uses the know as "True Bayesian Estimate" inspired on [IMDb rating](http://www.imdb.com/help/show_leaf?votestopfaq) with the following formula:
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```
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(WR) = (v ÷ (v + m)) × R + (m ÷ (v + m)) × C
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```
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**IMDb Implementation:**
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`WR`: weighted rating
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`R`: average for the movie (mean) = (Rating)
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`v`: number of votes for the movie = (votes)
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`m`: minimum votes required to be listed in the Top 250
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`C`: the mean vote across the whole report
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**Rating Implementation:**
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`WR`: weighted rating
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`R`: average for the resource
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`v`: number of votes for the resource
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`m`: average of the number of votes
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`C`: the average rating based on all resources
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## Install
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Add the following code on your `Gemfile` and run `bundle install`:
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```ruby
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gem 'rating'
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```
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Run the following task to create a Rating migration:
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```bash
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rails g rating:install
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```
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Then execute the migrations to create the to create tables `rating_rates` and `rating_ratings`:
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```bash
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rake db:migrate
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```
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## Usage
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Just add the callback `rating` to your model:
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```ruby
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class Author < ApplicationRecord
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rating
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end
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```
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Now this model can vote or receive votes.
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### rate
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You can vote on some resource:
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```ruby
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author = Author.last
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resource = Article.last
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author.rate(resource, 3)
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```
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### rating
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A voted resource exposes a cached data about it state:
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```ruby
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resource = Article.last
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resource.rating
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```
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It will return a `Rating` object that keeps:
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`average`: the normal mean of votes;
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`estimate`: the true Bayesian estimate mean value (you should use this over average);
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`sum`: the sum of votes for this resource;
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`total`: the total of votes for this resource.
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### rate_for
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You can retrieve the rate of some author gave to some resource:
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```ruby
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author = Author.last
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resource = Article.last
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author.rate_for resource
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```
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It will return a `Rate` object that keeps:
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`author`: the author of vote;
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`resource`: the resource that received the vote;
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`value`: the value of the vote.
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### rated?
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Maybe you want just to know if some author already rated some resource and receive `true` or `false`:
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```ruby
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author = Author.last
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resource = Article.last
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author.rated? resource
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```
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### rates
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You can retrieve all rates received by some resource:
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```ruby
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resource = Article.last
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resource.rates
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```
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It will return a collection of `Rate` object.
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### rated
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In the same way you can retrieve all rates that some author received:
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```ruby
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author = Author.last
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author.rated
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```
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It will return a collection of `Rate` object.
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### order_by_rating
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You can list resource ordered by rating data:
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```ruby
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Article.order_by_rating
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```
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It will return a collection of resource ordered by `estimate desc` as default.
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The order column and direction can be changed:
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```ruby
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Article.order_by_rating :average, :asc
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```
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It will return a collection of resource ordered by `Rating` table data.
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### Scope
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All methods support scope query, since you may want to vote on items of a resource instead the resource itself.
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Let's say an article belongs to one or more categories and you want to vote on some categories of this article.
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```ruby
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category_1 = Category.first
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category_2 = Category.second
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author = Author.last
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resource = Article.last
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```
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In this situation you should scope the vote of article with some category:
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**rate**
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```ruby
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author.rate resource, 3, scopeable: category_1
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author.rate resource, 5, scopeable: category_2
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```
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Now `resource` has a rating for `category_1` and another one for `category_2`.
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**rating**
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Recovering the rating values for resource, we have:
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```ruby
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resource.rating
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# nil
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```
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But using the scope to make the right query:
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```ruby
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resource.rating scope: category_1
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# { average: 3, estimate: 3, sum: 3, total: 1 }
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resource.rating scope: category_2
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# { average: 5, estimate: 5, sum: 5, total: 1 }
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```
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**rated**
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On the same way you can find your rates with a scoped query:
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```ruby
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author.rated scope: category_1
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# { value: 3, scopeable: category_1 }
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```
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**rates**
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The resource still have the power to consult its rates:
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```ruby
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article.rates scope: category_1
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# { value: 3, scopeable: category_1 }
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article.rates scope: category_2
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# { value: 3, scopeable: category_2 }
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```
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**order_by_rating**
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To order the rating you do the same thing:
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```ruby
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Article.order_by_rating scope: category_1
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```
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### Records
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Maybe you want to recover all records with or without scope, so you can add the suffix `_records` on relations:
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```ruby
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category_1 = Category.first
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category_2 = Category.second
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author = Author.last
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resource = Article.last
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author.rate resource, 1
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author.rate resource, 3, scopeable: category_1
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author.rate resource, 5, scopeable: category_2
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author.rating_records
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# { average: 1, estimate: 1, scopeable: nil , sum: 1, total: 1 },
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# { average: 3, estimate: 3, scopeable: category_1, sum: 3, total: 1 },
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# { average: 5, estimate: 5, scopeable: category_2, sum: 5, total: 1 }
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author.rated_records
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# { value: 1 }, { value: 3, scopeable: category_1 }, { value: 5, scopeable: category_2 }
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article.rates_records
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# { value: 1 }, { value: 3, scopeable: category_1 }, { value: 5, scopeable: category_2 }
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```
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### As
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If you have a model that will only be able to rate but not to receive a rate, configure it as `author`.
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An author model still can be rated, but won't genarate a Rating record with all values as zero to warm up the cache.
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```ruby
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rating as: :author
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```
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## Love it!
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Via [PayPal](https://www.paypal.com/cgi-bin/webscr?cmd=_donations&business=X8HEP2878NDEG&item_name=rating) or [Gratipay](https://gratipay.com/rating). Thanks! (:
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