foca / hal

Simple authorization framework for ruby

HAL. Minimalist authorization framework for Ruby¶ ↑

HAL is a class-based authorization framework for Ruby. It lets you define authorization rules on classes, which will then be applied to all instances of said classes. For example:

class User < Struct.new(:name); end
dave = User.new("Dave")

HAL.rules_for User do
  def open_the_pod_bay_doors?
    subject.name != "Dave"
  end
end

HAL.can(dave).open_the_pod_bay_doors? #=> false

When defining rules you can access a subject method, which will reference whatever object you pass to can.

You also have a more powerful version of can, called can!, which takes a block and will raise HAL::ICantLetYouDoThat if the block evaluates to false:

HAL.can!(dave) {|can| can.open_the_pod_bay_doors? } #=> raises!

Finally, you can include HAL into your classes to get can and can! as helper methods.

class UsersController < ApplicationController
  include HAL

  before_filter :check_permissions, :only => [:edit, :update, :destroy]

  def check_permissions
    unless can(current_user).edit_user?(current_user)
      redirect_to users_path, :alert => "I can't let you do that, Dave"
    end
  end
end

Installing¶ ↑

As a RubyGem

gem install hal

For rails 2.3, add to your config/environment.rb:

config.gem "hal", :lib => "hal/rails"

For rails 3, add to your Gemfile:

gem "hal", :require => "hal/rails"