Merit Gem: Reputation rules (badges, points and rankings) for Rails applications

Requirements

• ActiveRecord or Mongoid

Installation

1. Add gem 'merit' to your Gemfile
2. Run rails g merit:install
3. Run rails g merit MODEL_NAME
4. Depending on your ORM

• ActiveRecord: Run rake db:migrate
• Mongoid: Set config.orm = :mongoid in config/initializers/merit.rb

5. Define badges you will use in config/initializers/merit.rb
6. Configure reputation rules for your application in app/models/merit/*

---

Defining badge rules

You may give badges to any resource on your application if some condition holds. Badges may have levels, and may be temporary. Define rules on app/models/merit_badge_rules.rb:

grant_on accepts:

• 'controller#action' string (similar to Rails routes)
• :badge for badge name
• :level for badge level
• :to method name over target_object which obtains object to badge
• :model_name (string) define controller's name if it differs from the model (like RegistrationsController for User model).
• :multiple (boolean) badge may be granted multiple times
• :temporary (boolean) if the receiver had the badge but the condition doesn't hold anymore, remove it. false by default (badges are kept forever).
• &block
  • empty (always grants)
  • a block which evaluates to boolean (recieves target object as parameter)
  • a block with a hash composed of methods to run on the target object with expected values

Examples

grant_on 'comments#vote', :badge => 'relevant-commenter', :to => :user do |comment|
  comment.votes.count == 5
end

grant_on ['users#create', 'users#update'], :badge => 'autobiographer', :temporary => true do |user|
  user.name.present? && user.address.present?
end

Grant manually

You may also grant badges "by hand":

Badge.find(3).grant_to(current_user)

---

Defining point rules

Points are a simple integer value which are given to "meritable" resources. They are given on actions-triggered, either to the action user or to the method(s) defined in the :to option. Define rules on app/models/merit_point_rules.rb:

Examples

score 10, :on => [
  'users#update'
]

score 20, :on => [
  'comments#create',
  'photos#create'
]

:to method(s) work as in badge rules: they are sent to the target_object. In the following example, after a review gets created both review.reviewer and review.reviewed are granted 15 points:

score 15, :on => 'reviews#create', :to => [:reviewer, :reviewed]

---

Defining rank rules

5 stars is a common ranking use case. They are not given at specified actions like badges, you should define a cron job to test if ranks are to be granted.

Define rules on app/models/merit_rank_rules.rb:

set_rank accepts:

• :level ranking level (greater is better)
• :to model or scope to check if new rankings apply
• :level_name attribute name (default is empty and results in 'level' attribute, if set it's appended like 'level_#{level_name}')

Check for rules on a rake task executed in background like:

task :cron => :environment do
  Merit::RankRules.new.check_rank_rules
end

Examples

set_rank :level => 2, :to => Commiter.active do |commiter|
  commiter.branches > 1 && commiter.followers >= 10
end

set_rank :level => 3, :to => Commiter.active do |commiter|
  commiter.branches > 2 && commiter.followers >= 20
end

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To-do list

• add an error handler for inexistent badges.
• rails g merit MODEL_NAME shouldn't create general migrations again.
• Abstract User (rule.rb#51 for instance) into a Merit option.
• Should namespace app/models into Merit module.
• rescue ActiveRecord::... should depend on ORM used
• :value parameter (for star voting for example) should be configurable (depends on params[:value] on the controller).
• Make fixtures for integration testing (now creating objects on test file!).

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Contributors

• Tute Costa
• Juan Schwindt
• Eric Knudtson (Chef Surfing)
• A4bandas media