Ability Class, from ActiveRecord

_item.html.erb

<!-- CUT TO _banco.html.erb -->
<tr>
	<td><%= bank.code %></td>
	<td><%= bank.name %></td>
	<td><%= bank.cnpj8 %></td>
	
	<td id="td_action">
		<% if can? :read, Bank %> <%= link_to (row_link 'show'), bank %><% end %>
 		<% if can? :update, Bank %> <%= link_to (row_link 'edit'), edit_bank_path(bank) %><% end %>
  	<% if can? :destroy, Bank %><%= link_to (row_link 'delete'), bank, :confirm => 'Sure?', :method => :delete %><% end %>
	</td>
</tr>
<!-- END CUT TO -->

Ability.rb

# encoding: utf-8

class Ability
  include CanCan::Ability

  def initialize(user)
    user ||= User.new # guest
    user.roles.each do |role|
      role.permissions.each do |permission|
        if permission.subject_class == 'all'
          v_class = :all
        else
          v_class = permission.subject_class.constantize
        end
        if permission.subject_id.nil?
          can permission.action.to_sym, v_class
        else
          can permission.action.to_sym, v_class, :id => permission.subject_id
        end
      end
    end
  end
  
end

BanksController.rb

...

helper_method :permission


  def self.permission
  	return Bank.name, "Nice Banks Caption"
  end

wherever_you_want.rb

def setup_actions_controllers_db

		write_permission("all", "manage", "Everything", "Every Action", true)

		controllers = Dir.new("#{RAILS_ROOT}/app/controllers").entries
		controllers.each do |controller|
			if controller =~ /_controller/
				c_instance = controller.camelize.gsub(".rb","").constantize.new
			end
		end
		
		RestrictController.subclasses.each do |controller|
			is_rest = controller.respond_to?(:index) && controller.respond_to?(:new) && controller.respond_to?(:create) && controller.respond_to?(:update) && controller.respond_to?(:edit) && controller.respond_to?(:show) && controller.respond_to?(:delete)
			if controller.respond_to?(:permission)
				
				clazz, description = controller.permission
				write_permission(clazz, "manage", description, "Every Action")
				controller.action_methods.each do |action|
					if action.to_s.index("_callback").nil?
						action_desc, cancan_action = eval_cancan_action(action)
						write_permission(clazz, cancan_action, description, action_desc)
					end
				end
			end
		end
		
	end
	
	# This looks DAMN ugly, needs fixing.
	def eval_cancan_action(action)
		case action.to_s
		when "index", "show", "search"
			cancan_action = "read"
			action_desc = "Read-only"
		when "create", "new"
			cancan_action = "create"
			action_desc = "Insert only"
		when "edit", "update"
			cancan_action = "update"
			action_desc = "Update Only"
		when "delete", "destroy"
			cancan_action = "delete"
			action_desc = "Delete Only"
		else
			cancan_action = action.to_s
			action_desc = "Others: " << cancan_action
		end
		return action_desc, cancan_action
	end

	def write_permission(class_name, cancan_action, name, description, force_id_1 = false)
		permission  = Permission.find(:first, :conditions => ["subject_class = ? and action = ?", class_name, cancan_action]) 
		if not permission
			permission = Permission.new
			permission.id = 1 unless not force_id_1
			permission.subject_class =  class_name
			permission.action = cancan_action
			permission.name = name
			permission.description = description
			permission.save
		else
			permission.name = name
			permission.description = description
			permission.save
		end
	end