authorize_if

Minimalistic authorization library for Ruby and Rails applications. It provides methods authorize_if and authorize, that evaluate inline or pre-defined authorization rules and raise exception if rule evaluates to false.

API documentation

Contents:

authorize_if - inline authorization

• Exception handling
• Customization of an exception object

authorize - authorization using pre-defined authorization rules

• Organizing authorization rules

Installation

Using "authorize_if" outside of Ruby on Rails controllers

Contributing

License

---

authorize_if

Accepts any truthy or falsey Ruby object.

class ArticlesController < ActionController::Base
  def index
    authorize_if current_user
    # ...
  end

  def show
    article = Article.find(params[:id])

    authorize_if article.authored_by?(current_user) ||
                 article.published?
    # ...
  end

  def edit
    article = Article.find(params[:id])

    authorize_if can_manage?(article)
    # ...
  end

  private

  def can_manage?(article)
    # ...
  end
end

Exception handling

It raises AuthorizeIf::NotAuthorizedError exception, which you can rescue right in the controller action

class ArticlesController < ApplicationController
  def index
    authorize_if current_user
    # ...

  rescue AuthorizeIf::NotAuthorizedError
    head 404

  end
end

or with rescue_from in ApplicationController:

class ApplicationController < ActionController::Base
  rescue_from AuthorizeIf::NotAuthorizedError do |exception|
    head 404

  end
end

Customization of an exception object

If block is given, authorize_if yields the block with an exception object. This allows to set custom error message, which is going to be used when exception is raised.

Also you can use key-value store(plain Ruby hash), context, to store any data, and access it in the exception handling block.

class ArticlesController < ApplicationController
  def index
    authorize_if(current_user) do |exception|
      exception.message = "You are not authorized!"

      exception.context[:request_ip] = "192.168.1.1"
    end
    # ...
  end
end

class ApplicationController < ActionController::Base
  rescue_from AuthorizeIf::NotAuthorizedError do |exception|
    exception.message
    # => "You are not authorized!"

    exception.context[:request_ip]
    # => "192.168.1.1"
  end
end

authorize

You can define authorization rules for controller actions like this

"authorize_#{action_name}?"

And then call authorize, which is going to find and evaluate corresponding authorization rule.

class ArticlesController < ActionController::Base
  def index
    authorize

    # ...
  end

  private

  def authorize_index?
    current_user.present?
  end
end

authorize accepts any arguments and passes them to authorization rule.

class ArticlesController < ActionController::Base
  def edit
    article = Article.find(params[:id])

    authorize(article)

    # ...
  end

  private

  def authorize_edit?(article)
    article.author == current_user
  end
end

It also accepts customization block, and yields an exception object:

class ArticlesController < ActionController::Base
  def edit
    article = Article.find(params[:id])

    authorize(article) do |exception|
      exception.message = "You are not authorized!"
      exception.context[:request_ip] = "192.168.1.1"
    end

  rescue AuthorizeIf::NotAuthorizedError => e
    e.message
    # => "You are not authorized!"

    e.context[:request_ip]
    # => "192.168.1.1"
  end

  private

  def authorize_edit?(article)
    article.author == current_user
  end
end

Organizing authorization rules

You can extract rules into a module and include it to the controller.

class ArticlesController < ActionController::Base
  include AuthorizationRules

  def index
    authorize

    # ...
  end
end

module AuthorizationRules
  def authorize_index?
    current_user.present?
  end
end

Installation

Add gem to your application's Gemfile:

gem 'authorize_if'

And then execute:

$ bundle

Or install it manually:

$ gem install authorize_if

Using "authorize_if" outside of Ruby on Rails controllers

Include AuthorizeIf module, provided by gem, to any Ruby class and you'll get authorize and authorize_if methods.

Contributing

1. Fork it ( https://github.com/vrybas/authorize_if/fork )
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create a new Pull Request

License

Copyright 2016 Vladimir Rybas. MIT License (see LICENSE for details).