announcement-test/app/models/bulletin_feed.rb

class BulletinFeed
  include Mongoid::Document
  include Mongoid::Timestamps
  include Slug

	field :title, as: :slug_title, type: String, localize: true
	field :tag_ids, type: Array, default: []
  before_save do
    BulletinFeedCache.where(uid: self.uid).destroy
  end
end