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A simple and elegant solution to authorization suitable for most small and medium-sized projects.
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README.rdoc

BaseAuth

0.2.2

Now Ruby 1.9 compatible!

Best Authorization System Ever

Installation

Install it as you would any other plugin from github, i.e.

script/plugin install git://github.com/aenima/base-auth.git

Authorization by Controller

Key concept

This plugin makes 2 assumptions:

  • you have a current_user method in your controller which returns the currently signed in user which you want to check authorization for.

  • you check authorization using instance methods of your user objects

This worked really well for me so far, so there's a slight chance it will also work for you.

Using as a before filter

Simple example:

class ArticleController < ApplicationController
  deny :user => :is_guest?
end

The above example will deny all guest access (will call current_user.is_guest? method to determine if the user is a guest or not). If you want to allow guests to list articles, but nothing more, use:

allow :index, :user => :is_guest?

or

allow :only => :index, :user => :is_guest?

if you want to allow every user who is guest OR admin, you'd go:

allow :index, :user => [ :is_guest?, :is_admin? ]

if you give an Array as :user value, at least one condition has to be met. For more sophisticated conditions you can pass a string, which will be instance_eval'd:

allow :index, :user => 'is_guest? or ( is_admin? and is_moderator? )'

Still, there are cases when you want to check something in the controller. In that case you can use :exec param instead of :user like this:

class ArticleController < ApplicationController
  allow :exec => :check_auth

  def check_auth
    session[:allowed] == 'yes'
  end
end

You can also pass a string, which will be eval'd, or a Proc, which will be called.

If you pass a method which accepts arguments, an object will be passed to it as a parameter. Which obejct? By default an instance variable named after singluarized controller name. So:

class ArticleController < ApplicationController
  allow :edit, :update, :user => :owns?
end

Will call current_user.owns?( @article ) to check for permission. You can override this by passing :object argument, which can be a Symbol (naming instance variable to be used) or the object itself.

By default an Authorization::PermisionDenied exception will be raised. You can also use :method parameter to specify which method should be called instead or :redirect_to to redirect user instead.

With :message parameter you can pass a message that will be stored in exception.

Using in actions

In actions you can use allow!, deny!, allow? and deny? methods. The ones with '!' will raise an exception, while the ones with '?' will only return true or false:

def destroy
  allow! :user => :owns?
  @article.destroy
end

Using in views

You can use allow and deny methods in your views and pass them a block to execute:

<% allow :user => :is_admin? do %>

Only admins can see that!

<% end>

<% deny :user => :is_guest? do %>

You can't see it if you're a guest.

<% end %>

Authorization by model

Since version 0.2 the code has been modularized a bit and you can also authorize by model (single instance for now). It's usage is dead easy and straightforward. You just have to implement authorize instance method in a given model (as a parameter it takes user to authorize against). You don't even have to do it if you're satisfied with default implementation (supplied with plugin):

def authorize(user)
  user.id == self.user_id
end

This method is used by authorize! instance method which works exactly like allow! - i.e. does nothing (returns the model) if authorized and throws Authorization::PermissionDenied if not authorized:

@item = ItemModel.find(35).authorize!(current_user) #throws an exception if current_user is not authorized

Notes

If you're using rails older than 2.0 rescuing exceptions can be a pain. For rails 1.2 I recommend using exceptional plugin:

agilewebdevelopment.com/plugins/exceptional

ToDo

  • add support for :if parameted (should behave like the one in validations)

  • make it possible to configure default behavior (so you don't have to pass :method parameter everywhere if you always want to call a method instead of raising exception)

  • better documentation

  • model authorization: configuration of authorize! method to allow for redirection etc. (now it can only throw exceptions)

  • model authorization: authorize_for!(:actionname), i.e. let user define and use per-action authorization for a given model (different auth checks for different actions), by authorize_for_actionname methods in model

  • refactor the code structure (divide into three files)

Credits & Licensing

Copyright © by Robert Nasiadek at <robert@aenima.pl>. Maintenance and small modifications (model-based auth) by Tomasz Stachewicz <tomasz.stachewicz@aenima.pl>. Distributed under MIT license.

You can find more cool stuff by Aenima on our Github (github.com/aenima) and our blog (blog.aenima.pl/).

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