Umpire

Umpire is a very lightweight authorization lib that uses policy classes to define rules

Add this line to your application's Gemfile:

gem 'umpire'

And then execute:

$ bundle

Or install it yourself as:

$ gem install umpire

Umpire consists of a base policy class that you need to extend and a helper that you can use in your app. Because it's doesn't depend on rails, you need to include the Umpire helper in your ApplicationHelper and your ApplicationController or whatever other class you might need to use it in:

include Umpire::AuthHelper

I use that in a rails lib, so by default the lib uses a current_user method to get the subject from, but if you don't have it - no worries, you can still pas a subject on your own.

Let's make a simple Policy class and use it in a rails view:

class SchoolPolicy < Umpire::Policy
  # the only method you need to overwrite
  # return all the allowed actions here
  # @subject is the subject (current_user) by default
  # and the object is @object - in this exapmle it could be a
  def rules
    allowed = [:go_to_school]
    allowed << :take_cs_201  @subject.has_taken(:cs_101)
    allowed
  end
end

You can now use the policy class with the helper like this:

<%= render partial: 'modules/cs_201' if can? :take_cs_201, using: SchoolPolicy %>

This will check call has_taken(:cs_101) on the result of current_user

Other usage examples:

# with subject
can? User.find(1), :drive, car, using: HighwayCode

# without subject (assumes current_user if available)
can? :drive, car, using: HighwayCode

# multiple policies
can? :park, car, using: [HighwayCode, ParkingRules]

# without object
can? :cook_spaghetti, using: [KitchenPolicy]

# multiple actions
can? [:order, :drink], beer, using: BarPolicy

After checking out the repo, run bundle to install dependencies. Then, run bundle exec rake rspec to run the tests.

To install this gem onto your local machine, run bundle exec rake install.

Bug reports and pull requests are welcome on GitHub at https://github.com/muxcmux/umpire.

The gem is available as open source under the terms of the MIT License.