Last Updated: February 25, 2016

"Invalidate" cached key when record/document change

Reading this blog post I found this way to expire a cache very useful.

Consider following example:

class Place < ActiveRecord::Base
 def flickr_place
 flickr = FlickRaw::Flickr.new
 @flickr_place ||= Rails.cache.fetch("places/#{self.id}-#{self.updated_at}/flickr/place_id", expires_in: 7.days) do
 # Some code here
 end
 end
end

"... By using self.updated_at inside the cache key we ensure that the cache is automatically invalidated if we update the place (which could include new co-ordinates)."

#rails

#caching

#low-level-cache