A true Bayesian rating system with scope and cache enabled.
This is Raty: https://github.com/wbotelhos/raty 🌟
Rating uses the know as "True Bayesian Estimate" inspired on IMDb rating with the following formula:
(WR) = (v ÷ (v + m)) × R + (m ÷ (v + m)) × C
IMDb Implementation:
WR
: weighted rating
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
Rating Implementation:
WR
: weighted rating
R
: average for the resource
v
: number of votes for the resource
m
: average of the number of votes
C
: the average rating based on all resources
Add the following code on your Gemfile
and run bundle install
:
gem 'rating'
Run the following task to create the Rating migration:
rails g rating:install
Then execute the migrations to create the to create tables rating_rates
and rating_ratings
:
rake db:migrate
Just add the callback rating
to your model:
class Author < ApplicationRecord
rating
end
Now this model can vote or receive votes.
You can vote on some resource:
author = Author.last
resource = Article.last
author.rate resource, 3
A voted resource exposes a cached data about it state:
resource = Article.last
resource.rating
It will return a Rating
object that keeps:
average
: the normal mean of votes;
estimate
: the true Bayesian estimate mean value (you should use this over average);
sum
: the sum of votes for this resource;
total
: the total of votes for this resource.
You can retrieve the rate of some author gave to some resource:
author = Author.last
resource = Article.last
author.rate_for resource
It will return a Rate
object that keeps:
author
: the author of vote;
resource
: the resource that received the vote;
value
: the value of the vote.
Maybe you want just to know if some author already rated some resource and receive true
or false
:
author = Author.last
resource = Article.last
author.rated? resource
All rating received.
Article.first.rates
It will return a collection of Rate
object.
All rating given.
Author.first.rated
It will return a collection of Rate
object.
You can list resource ordered by rating data:
Article.order_by_rating
It will return a collection of resource ordered by estimate desc
as default.
The order column and direction can be changed:
Article.order_by_rating({ column: :average, direction: :asc })
It will return a collection of resource ordered by Rating
table data.
All methods support scope query, since you may want to vote on items of a resource instead the resource itself. Let's say an article belongs to one or more categories and you want to vote on some categories of this article.
category_1 = Category.first
category_2 = Category.second
author = Author.last
resource = Article.last
In this situation you should scope the vote of article with some category:
rate
author.rate resource, 3, scope: category_1
author.rate resource, 5, scope: category_2
Now resource
has a rating for category_1
and another one for category_2
.
rating
Recovering the rating values for resource, we have:
resource.rating
# nil
But using the scope to make the right query:
resource.rating scope: category_1
# { average: 3, estimate: 3, sum: 3, total: 1 }
resource.rating scope: category_2
# { average: 5, estimate: 5, sum: 5, total: 1 }
rated
On the same way you can find your rates with a scoped query:
author.rated scope: category_1
# { value: 3, scopeable: category_1 }
rates
The resource still have the power to consult its rates:
article.rates scope: category_1
# { value: 3, scopeable: category_1 }
article.rates scope: category_2
# { value: 3, scopeable: category_2 }
order_by_rating
To order the rating you do the same thing:
Article.order_by_rating({ scope: category_1 })
Maybe you need to use more than one scope to make a rate, so you can use the extra_scopes
options.
This feature is enable only to restrict the rate, the rating calculation will ignore it.
Example situation: I have a Profile (resource) that belongs to some Category (scope) and the Client (author) will rate this Profile based on each Lead (extra scope) this Profile made. The Client can vote just one time on each lead, but many times to that Profile. The Profile has a rating score based on all leads made on that Category.
scope = Category.first
author = Client.last
resource = Profile.last
lead = Lead.last
author.rate resource, 5, extra_scopes: { lead_id: lead.id }, scope: scope
- The extra scopes fields is not present into gem, so you cannot use
{ lead: lead }
, for example.
All methods listed on Scope session allows extra_scopes
as additional condition too.
Maybe you want to recover all records with or without scope, so you can add the suffix _records
on relations:
category_1 = Category.first
category_2 = Category.second
author = Author.last
resource = Article.last
author.rate resource, 1
author.rate resource, 3, scope: category_1
author.rate resource, 5, scope: category_2
author.rating_records
# { average: 1, estimate: 1, scopeable: nil , sum: 1, total: 1 },
# { average: 3, estimate: 3, scopeable: category_1, sum: 3, total: 1 },
# { average: 5, estimate: 5, scopeable: category_2, sum: 5, total: 1 }
author.rated_records
# { value: 1 }, { value: 3, scopeable: category_1 }, { value: 5, scopeable: category_2 }
article.rates_records
# { value: 1 }, { value: 3, scopeable: category_1 }, { value: 5, scopeable: category_2 }
If you have a model that will only be able to rate but not to receive a rate, configure it as author
.
An author model still can be rated, but won't genarate a Rating record with all values as zero to warm up the cache.
rating as: :author
Maybe you want include a comment
together your rating or even a fingerprint
field to make your rating more secure.
So, first you will need to add more fields to the Rating::Rate
table:
class AddCommentAndFingerprintOnRatingRates < ActiveRecord::Migration
def change
add_column :rating_rates, :comment, :text
add_reference :rating_rates, :fingerprint, foreign_key: true, index: true, null: false
end
end
As you can seed, we can add any kind of field we want. Now we just provide this values when we make the rate:
author = Author.last
resource = Article.last
comment = 'This is a very nice rating. s2'
fingerprint = Fingerprint.new(ip: '127.0.0.1')
author.rate resource, 3, metadata: { comment: comment, fingerprint: fingerprint }
Now you can have this data into your model normally:
author = Author.last
rate = author.rates.last
rate.comment # 'This is a very nice rating. s2'
rate.fingerprint # <Fingerprint id:...>
rate.value # 3
If you need to warm up a record with scope, you need to setup the scoping
relation.
class Resource < ApplicationRecord
rating scoping: :categories
end
Now, when a resource is created, the cache will be generated for each related category
as scopeable
.
You can choose the table where Rating will write the data via YAML config.
You should just to provide a config/rating.yml
file with the following content:
rating:
rate_table: reviews
rating_table: review_ratings
Now the rates will be written on reviews
table over rating_rates
and calculation will be on review_ratings
over rating_ratings
.
You can change one table o both of them.
Since you can to use 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.
rating:
validations:
rate:
uniqueness:
case_sensitive: false
scope:
- author_type
- resource_id
- resource_type
- scopeable_id
- scopeable_type
- scope_1
- scope_2
All rating values are grouped by its own scope, but you can disable it and group all of them together.
rating unscoped_rating: true
author = User.last
resource = Article.last
scope = Category.last
author.rate resource, 1, scope: scope
author.rate resource, 2, scope: scope
author.rate resource, 3
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.
The rating record is always saved on the record with scopeable
as nil
.
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:
rating where: 'approved = true'
author = User.last
resource = Article.last
author.rate resource, 1, extra_scope: { approved: false }
author.rate resource, 5, extra_scope: { approved: true }
As you can see, now, only the rate with value 5
will be included on the final rating.
To run all specs, run the following rakes:
bundle exec rake spec
bundle exec rake spec_config
bundle exec rake spec_config_with_extra_scopes