What's the point of Rolify and CanCan?

Question

I'm working on a RoR project and I'm a little confused about this new gem that was recommended for my purposes, Rolify. As I understand it, rolify does pretty much the same thing as CanCan except it persists abilities (roles for rolify) to the database. However, all over the Rolify wiki, I see instructions on using Rolify with CanCan.

So basically, I'm wondering what's the difference between Rolify and CanCan? When should I use the one and not the other?

Messalina

Answer 1

CanCan is used for managing authorization from the application standpoint is what lets you restrict X controller/action to X user.

When you want to dive into a deeper fine grained of control you use Rolify. Rolify, goes beyond the simple

if user.role == :super_admin
  # do something pretty cool stuff
elsif user.role == :admin
  # do some more awesome stuff

by allowing you to add roles to resources. Let's say you have a forum application, where you want an user to be able to have a moderator role on the Gaming Board. You would use rolify to by

user = User.find(2)
user.add_role :moderator, Forum.where(type: 'Gaming')

Rolify also let's you do this to a class by using the class itself instead of an instance (in case you want an user to be a moderator of all the boards)

user = User.find(2)
user.add_role :moderator, Forum

After that it lets you easily query the resources/class to find out who was access to what. On top of helping you manage the roles scope.

Sangria

So, it doesn't make sense to use them together? Just use one or the other? – Messalina

Answer 2

CanCan is an authorization library that allows you to set up rules on who can or can't perform certain actions.

Rolify is a roles library which helps you create roles which you can then use in your Cancan authorization rules.

Dissection