439 lines
10 KiB
Markdown
439 lines
10 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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[](https://codeclimate.com/github/wbotelhos/rating/maintainability)
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[](https://www.patreon.com/wbotelhos)
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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 the Rating migration:
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```sh
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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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```sh
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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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All rating received.
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```ruby
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Article.first.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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All rating given.
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```ruby
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Author.first.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, scope: category_1
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author.rate resource, 5, scope: 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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### Extra Scopes
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Maybe you need to use more than one scope to make a rate, so you can use the `extra_scopes` options.
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This feature is enable **only** to restrict the rate, the rating calculation will **ignore** it.
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Example situation: I have a Profile (resource) that belongs to some Category (scope) and the Client (author) will rate
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this Profile based on each Lead (extra scope) this Profile made. The Client can vote just one time on each lead, but many
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times to that Profile. The Profile has a rating score based on all leads made on that Category.
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```ruby
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scope = Category.first
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author = Client.last
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resource = Profile.last
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lead = Lead.last
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author.rate resource, 5, extra_scopes: { lead_id: lead.id }, scope: scope
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```
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* The extra scopes fields is not present into gem, so you cannot use `{ lead: lead }`, for example.
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All methods listed on [Scope](#scope) session allows `extra_scopes` as additional condition too.
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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, scope: category_1
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author.rate resource, 5, scope: 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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### Metadata
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Maybe you want include a `comment` together your rating or even a `fingerprint` field to make your rating more secure.
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So, first you will need to add more fields to the `Rating::Rate` table:
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```ruby
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class AddCommentAndFingerprintOnRatingRates < ActiveRecord::Migration
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def change
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add_column :rating_rates, :comment, :text
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add_reference :rating_rates, :fingerprint, foreign_key: true, index: true, null: false
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end
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end
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```
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As you can seed, we can add any kind of field we want. Now we just provide this values when we make the rate:
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```ruby
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author = Author.last
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resource = Article.last
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comment = 'This is a very nice rating. s2'
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fingerprint = Fingerprint.new(ip: '127.0.0.1')
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author.rate resource, 3, metadata: { comment: comment, fingerprint: fingerprint }
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```
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Now you can have this data into your model normally:
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```ruby
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author = Author.last
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rate = author.rates.last
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rate.comment # 'This is a very nice rating. s2'
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rate.fingerprint # <Fingerprint id:...>
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rate.value # 3
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```
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### Scoping
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If you need to warm up a record with scope, you need to setup the `scoping` relation.
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```ruby
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class Resource < ApplicationRecord
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rating scoping: :categories
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end
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```
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Now, when a resource is created, the cache will be generated for each related `category` as `scopeable`.
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### Table Name
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You can choose the table where Rating will write the data via YAML config.
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You should just to provide a `config/rating.yml` file with the following content:
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```yml
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rating:
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rate_table: reviews
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rating_table: review_ratings
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```
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Now the rates will be written on `reviews` table over `rating_rates` and calculation will be on `review_ratings` over `rating_ratings`.
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You can change one table o both of them.
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### Validations
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#### Rate Uniqueness
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Since you can to use [Extra Scopes](#extra_scopes) to restrict rates and the original model `Rating::Rate` is inside gem, you can configure the uniqueness validation, from outside, to include this extra scopes.
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```yml
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rating:
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validations:
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rate:
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uniqueness:
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case_sensitive: false
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scope:
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- author_type
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- resource_id
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- resource_type
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- scopeable_id
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- scopeable_type
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- scope_1
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- scope_2
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```
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### Unscoped Rating
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All rating values are grouped by its own scope, but you can disable it and group all of them together.
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```ruby
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rating unscoped_rating: true
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author = User.last
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resource = Article.last
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scope = Category.last
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author.rate resource, 1, scope: scope
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author.rate resource, 2, scope: scope
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author.rate resource, 3
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```
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Now the `sum` will be `6` and the `total` will be `3` because all rating will be calculated into just one rating record ignoring the `scopeable` object.
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The rating record is *always* saved on the record with `scopeable` as `nil`.
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### where
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The `where` option can be used to filter the `Rating::Rate` records used to create the final `Rating::Rating`. You can filter only approved rates, for exemplo:
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```ruby
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rating where: 'approved = true'
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author = User.last
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resource = Article.last
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author.rate resource, 1, extra_scope: { approved: false }
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author.rate resource, 5, extra_scope: { approved: true }
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```
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As you can see, now, only the rate with value `5` will be included on the final rating.
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### Specs
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To run all specs, run the following rakes:
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```sh
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bundle exec rake spec
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bundle exec rake spec_config
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bundle exec rake spec_config_with_extra_scopes
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```
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### References
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- [Evan Miller](http://www.evanmiller.org/ranking-items-with-star-ratings.html)
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