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Upgrading to 1.6

ryanb edited this page Mar 10, 2011 · 4 revisions

This document explains what's new in CanCan 1.6. If you are just getting started with CanCan, first check out the README.

See Upgrading to 1.5 if you are using version 1.4 or older. Also check out the CHANGELOG for the full list of changes.

MetaWhere Support

If you have MetaWhere installed, it is now possible to use those queries in abilities.

can :read, Project, => 3
can :update, Article, :published_at.not_eq => nil

The & and | joining is not supported yet but hopefully will be soon. If you are interested in helping add this please see the issue tracker.


It is now possible to pass a scope instead of an SQL string when using a block in an ability.

can :read, Article, Article.published do |article|
  article.published_at <=

This is really useful if you have complex conditions which require joins. A couple caveats:

  • You cannot use this with multiple can definitions that match the same action and model since it is not possible to combine them. An exception will be raised when that is the case.
  • If you use this with cannot, the scope needs to be the inverse since it's passed directly through. For example, if you don't want someone to read discontinued products the scope will need to fetch non discontinued ones:
cannot :read, Product, Product.where(:discontinued => false) do |product|

It is only recommended to use scopes if a situation is too complex for a simple hash condition.

Conditionally check_authorization

The check_authorization method now supports :if and :unless options. Either one takes a method name as a symbol. This method will be called to determine if the authorization check will be performed. This makes it very easy to skip this check on all Devise controllers since they provide a devise_controller? method.

class ApplicationController < ActionController::Base
  check_authorization :unless => :devise_controller?
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