Cancan rolify : Define abilty on resource depending on role

Question

I wonder if their are a way of using cancan to define abilities depending on role for a specific resource.

For now i have something like this, but the problem is that it goes through each role the user have each time like if he has 2 times the role1 even if it's on different Stuff instances.

def initialize(user)
    @user = user || User.new
    @user.roles.map(&:name).each{|name| send(name)}
  end

 def role1
    can :manage, Stuff
 end

How can i optimize this ?

I've thought about something like:

def initialize(user)
    @user = user || User.new

     can :manage, Object do |object|
       roles = @user.roles.where(resource_id: object.id, resource_type: object.class)
       unless roles.empty?
         roles.map(&:name).each{|name| send(name)}
       end
     end
  end

But it still got the problem of getting the ":manage" action to any user that have any other ability on the ressource...

So are their any way to access to the resource instance in the initialize function of cancan ?

Answer 1

I've found something for avoiding the :manage using this issue https://github.com/ryanb/cancan/issues/133

so i've added

  def current_ability
    @current_ability = Ability.new(current_user, @resource)
  end

in the application_controller.rb in the controller just before the "authorize!" call i've defined an instance variable named @resource

like so:

def create
    project = Project.find(params[:project_id])
    @resource = project
    authorize! :create_stories, project
    ....
 end

and updated the ability.rb

 def initialize(user, resource)
    @user = user || User.new

    roles = @user.roles.where(resource_id: resource.id, resource_type: resource.class)
    if roles.empty?
      false
    else
      roles.map(&:name).each{|name| send(name)}
    end
  end

  def role1
    can :go_and_make_coffee
  end

so enjoy if it helps someone