ActsAsPermissible
This plugin enables any activerecord model to have permissions.
It provides a set of methods for querying the model’s permissions.
In addition, the plugin can generate roles support, which turns in into a full RBAC (Role Based Access Control) solution.
Any model which includes the line “acts_as_permissible” can have permissions, and with roles support it can also have roles which in turn have their own permissions.
Roles can also belong to roles, which creates a sort of inheritance hierarchy.
When permissions are calculated, the model’s permissions are merged with the model’s role permissions (if any), which in turn are merged with the role’s roles permissions, until a finite permissions hash is generated.
In the case of identical keys, a false value overrides a true value, a true value overrides a nil value, and a nil value is false.
Setup

script/generate permissible PermissionModelName [RoleModelName]

The role model name is optional. If you do not want the roles support generated, use the—skip-roles option.
examples:

script/generate permissible Permission Role
script/generate permissible Permission Group
script/generate permissible Allowance --skip-roles

use—skip-migration if you don’t want a migration created for the permissions model.
use—rspec to force rspec tests installed (currenty these are the only ones available).
Add any permissions you want to your permissions table.
Add any roles you want to your roles table.
Add user->role relationships in your roles_memberships table.
Add role->role relationships in your roles_memberships table.
Usage

    class User < Activerecord::Base
        acts_as_permissible
    end

Now a user will have the following methods:

    @user.permissions_hash() # => {:view_something => true, :delete_something => false}

    @user.has_permission?("view_something") # => true
    @user.has_permission?("view_something", "delete_something") # => false
    @user.has_permission?("delete_something") # => false
    @user.has_permission?("create_something") # => false

    @user.permissions_hash() # => {:view_something => true, :delete_something => false}
    @user.permissions << Permission.new(:action => "new_thing", :granted => true)
    @user.permissions_hash() # => {:view_something => true, :delete_something => false}
    @user.reload_permissions!() # => {:view_something => true, :delete_something => false, :new_thing => true}
    @user.permissions_hash() # => {:view_something => true, :delete_something => false, :new_thing => true}

This is useful for getting the hash again into memory after the permissions table was updated.
And with roles support:

    @user.in_role?("publisher") # => true
    @user.in_role?("publisher","advertiser") # => false
    @user.in_any_role?("publisher","advertiser") => true
    @user.full_permissions_hash() # will return a merged hash of user and roles permissions.

Copyright© 2008 Noam Ben-Ari, released under the MIT license