Ruby on Rails

class SiteSweeper < ActionController::Caching::Sweeper
    observe Article, Category

    def after_create(model)
      expire_cache_for(model)
    end

    def after_update(model)
      expire_cache_for(model)
    end

    def after_destroy(model)
      expire_cache_for(model)
    end

    private
    def expire_cache_for(model)
      expire_page controller: 'page', action: 'index'
    end
end

https://github.com/leandromoreira/playground.activeadmin/blob/master/app/sweepers/site_sweeper.rb

But I change my Article and the change do not expire the page, am I doing something wrong?