Motion::Authorization

This gem provides simple authorization to your RubyMotion app. It was inspired by both CanCan and Pundit. There are no dependencies, so it should work in all kinds of RubyMotion apps. Permissions are defined as "policy" classes (like Pundit) and queried with a syntax similar to CanCan.

Installation

Add this line to your application's Gemfile:

gem "motion-authorization"

And then execute:

$ bundle

Be sure to require "motion-authorization" in your Rakefile (unless you are using Bundler.require).

Usage

Step 1: Specify the current user.

This gem provides two different ways to specify the current user: directly or as a callback to be evaluated later. If setting directly, you will want to do that when the current user changes. Assuming you already have a method for fetching your current user, you can hook into your existing method by defining the current_user_method as a block.

Motion::Authorization.current_user = current_user_instance
# OR...
Motion::Authorization.current_user_method do
  MyAuthClass.current_user
end

Step 2: Include the DSL methods.

In any class where you want to check if the current user is authorized to do something, start by including the DSL methods:

class MyRubyMotionClass
  include Motion::Authorization::Methods
  # ...
end

Now you can use one of Motion::Authorization's query methods to check if the current user can do something. Let's say that we have a SecretMessage object, and we only want to display it if the current user is able to view it.

display_secret_message if can? :view, secret_message

Motion::Authorization provides several methods to choose from that may (or may not) make your code easier to read.

• can?
• permitted_to?
• authorized_to?
• authorised_to?

Choose the method which you like best.

Step 3: Define a Policy class.

Extending our previous example of can? :view, secret_message, Motion::Authorization will look for a class named SecretMessagePolicy with a method named view? which returns true or false.

Policy classes in Motion::Authorization are identical to those in Pundit. Typically, you will create a class within a policies directory, such as app/policies/secret_message_policy.rb. Next, you would define a class that accepts the current user and object that it is related to. Something like this:

class SecretMessagePolicy
  attr_accessor :user, :secret_message

  def initialize(user, secret_message)
    @user = user
    @secret_message = secret_message
  end

  def view?
    user.id == secret_message.owner.id
  end
end

Or even more simply by using Struct:

class SecretMessagePolicy < Struct.new(:user, :secret_message)
  def view?
    user.id == secret_message.owner.id
  end
end

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/andrewhavens/motion-authorization.

License

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