Add the following code on your `Gemfile` and run `bundle install`:
```ruby
gem 'rating'
```
Run the following task to create a Rating migration:
```bash
rails g rating:install
```
Then execute the migrations to create the to create tables `rating_rates` and `rating_ratings`:
```bash
rake db:migrate
```
## Usage
Just add the callback `rating` to your model:
```ruby
class User <ApplicationRecord
rating
end
```
Now this model can vote or be voted.
### rate
You can vote on some resource:
```ruby
author = User.last
resource = Article.last
author.rate(resource, 3)
```
### rating
A voted resource exposes a cached data about it state:
```ruby
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.
### rate_for
You can retrieve the rate of some author gave to some resource:
```ruby
author = User.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.
### rated?
Maybe you want just to know if some author already rated some resource and receive `true` or `false`:
```ruby
author = User.last
resource = Article.last
author.rated? resource
```
### rates
You can retrieve all rates made by some author:
```ruby
author = User.last
author.rates
```
It will return a collection of `Rate` object.
### rated
In the same way you can retrieve all rates that some author received:
```ruby
author = User.last
author.rated
```
It will return a collection of `Rate` object.
### order_by_rating
You can list resource ordered by rating data:
```ruby
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:
```ruby
Article.order_by_rating :average, :asc
```
It will return a collection of resource ordered by `Rating` table data.
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