# Does anybody out there know rails internals? **URL:** \ **Category:** Rails\ **Created:** [October 24, 2007, 4:28pm UTC](https://www.ruby-forum.com/t/does-anybody-out-there-know-rails-internals/118184 "2007-10-24T16:28:59Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![gonesail](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/35a633/32.png) [@gonesail](https://www.ruby-forum.com/u/gonesail)\ **Post date:** [October 24, 2007, 4:28pm UTC](https://www.ruby-forum.com/t/does-anybody-out-there-know-rails-internals/118184/1 "2007-10-24T16:28:59Z")
i need to call a sweeper directly from a model to expire cache (the sweeper is observing the model as usual). why is this not documented? seems like something that everybody would need to know!! ---
**Author:** ![gonesail](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/35a633/32.png) [@gonesail](https://www.ruby-forum.com/u/gonesail)\ **Post date:** [October 24, 2007, 6:46pm UTC](https://www.ruby-forum.com/t/does-anybody-out-there-know-rails-internals/118184/2 "2007-10-24T18:46:25Z")
come on people. this should be simple to do. the sweeper is observing the model … how do I call the sweeper.after\_save(record) method from the model? ---
**Author:** ![gonesail](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/35a633/32.png) [@gonesail](https://www.ruby-forum.com/u/gonesail)\ **Post date:** [October 24, 2007, 8:09pm UTC](https://www.ruby-forum.com/t/does-anybody-out-there-know-rails-internals/118184/3 "2007-10-24T20:09:49Z")
OK another approach: initialize a new sweeper and call from model. another gotcha the new method is private for ActionController::Caching::Sweeper. can anybody help with this? there’s no documentation. ---
**Author:** ![gonesail](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/35a633/32.png) [@gonesail](https://www.ruby-forum.com/u/gonesail)\ **Post date:** [October 24, 2007, 9:41pm UTC](https://www.ruby-forum.com/t/does-anybody-out-there-know-rails-internals/118184/4 "2007-10-24T21:41:02Z")
On 10/24/07, Gone S. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > OK another approach: initialize a new sweeper and call from model. > another gotcha the new method is private for > ActionController::Caching::Sweeper. can anybody help with this? > there’s no documentation. I haven’t used sweepers, so I’m not much help; but it looks like this is a singleton. So you would need SomeSweeper.instance to get at the singleton object. Not sure what you would do with it though… ---
**Author:** ![gonesail](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/35a633/32.png) [@gonesail](https://www.ruby-forum.com/u/gonesail)\ **Post date:** [October 24, 2007, 10:01pm UTC](https://www.ruby-forum.com/t/does-anybody-out-there-know-rails-internals/118184/5 "2007-10-24T22:01:53Z")
i did it!! from within the model call sweeper.instance.after\_save(parm) and you have expired the cache (assume after\_save is the name of the sweeper class method that is observing the model). you’re right it is a singleton … thanks. ---
**Author:** ![gonesail](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/35a633/32.png) [@gonesail](https://www.ruby-forum.com/u/gonesail)\ **Post date:** [October 24, 2007, 9:49pm UTC](https://www.ruby-forum.com/t/does-anybody-out-there-know-rails-internals/118184/6 "2007-10-24T21:49:49Z")
On 10/24/07, Bob S. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > singleton object. Not sure what you would do with it though… > Sweepers are half AR Observer and half controller filter. This means > they have to run from a controller. That’s where the methods for > expiring stuff lives. You’re probably better off using an Observer > then. – Rick O. [http://lighthouseapp.com](http://lighthouseapp.com) [http://weblog.techno-weenie.net](http://weblog.techno-weenie.net) [http://mephistoblog.com](http://mephistoblog.com)