Saru

Saru is an extraction of Ryan Bates' famous authorization library CanCan. As it is not really maintained anymore, we decided to extract the crucial portions from it, fixing and improving them for our needs.

Requirements

• Ruby >= 1.9.3

Differences to CanCan

• Working Ability definition using Blocks
• No Hash conditions
• No Ability aliases
• No Tests

Installation

Add this line to your application's Gemfile:

gem 'saru', github: 'thisisdmg/saru'

And then execute:

$ bundle install

Quick Start

require 'saru'

class Ability
  include Saru::Ability

  def initialize(user)
    user ||= User.new

    can(:create, Article) if user.admin?
    can :read, Article
  end
end

admin = User.find(42)
user = User.find(815)

admin_ability = Ability.new(admin)
admin_ability.can?(:create, Article) # => true
admin_ability.can?(:read, Article)   # => true

user_ability = Ability.new(user)
user_ability.can?(:create, Article) # => false
user_ability.can?(:read, Article)   # => true

Defining Abilies

ability = Ability.new(user)

# without condition, always allowed.
ability.can :read, Article

# "outer" condition given, allowed if true.
ability.can(:create, Article) if user.admin?

# block condition given, allowed to update a single Article if block evaluates
# to true (== anything except false and nil).
ability.can(:update, Article) do |article|
  article.user_id == user.id
end

# block condition given, allowed to update all Articles if block evaluates
# to true (== anything except false and nil).
ability.can(:update, Article) do
  user.roles.where(name: 'editor').exists?
end

# special actions and subjects:
# :manage as action means having access to all actions on an Object,
# :all as subject means having access to any Object.
ability.can(:manage, :all) if user.allmighty?

# multi-action/multi-subject
can [:create, :read, :update, :destroy], Article
can :read, [Article, Comment]
can [:create, :read, :update, :destroy], [Article, Comment]

# Abilites are inherited using the class hierarchy.
Vehicle = Class.new
Car = Class.new(Vehicle)

ability.can :drive, Vehicle
ability.can? :drive, Vehicle # => true
ability.can? :drive, Car     # => true

# disallow access, later defined abilities have precedence.
# rules inside an ability are evaluated from the bottom to the top,
# stopping if there's a matching one.
ability.can :manage, Article
ability.cannot :destroy, Article

ability.can? :create, Article  # => true
ability.can? :destroy, Article # => false

Rails 4

Add this line to your application's Gemfile:

gem 'saru', github: 'thisisdmg/saru', require: 'saru/rails'

And then execute:

$ bundle install

Generate ability.rb in app/models

$ bin/rails generate saru:ability

Helper Methods

• current_ability (uses current_user per default)
• can?(action, subject)
• cannot?(action, subject)
• authorize!(action, subject, message = nil) (will raise Saru::AccessDenied if not authorized)

License

Copyright (c) 2011 Ryan Bates

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.