abilities.rb

# app/models/abilities/base.rb
module Abilities
  class Base
    include CanCan::Ability
    def initialize(user)
    end
  end
end
# app/models/abilities/my_model.rb
module Abilities
  class MyModel < Base
    def initialize(user)
      super(user)
      return unless user.present?
      can :manage, ::MyModel, user_id: user.id
    end
  end
end
# app/models/abilities/factory.rb
module Abilities
  class Factory
    def self.ability_for(controller_class, user)
      {
        MyModelsController => Abilities::MyModel
      }.fetch(controller_class) do
        # Use the base ability by default
        Abilities::Base
      end.new(user)
    end
    end
  end
end