Hello list! I need to expire fragment caches from a background job. The usual way to expire caches is to create a cache sweeper and put the observer hooks into the controller. That is fine as long as database is only modified through controller actions.
But in this case I have a background job importing data, and that needs to invalidate fragment caches for records it touches. The most elegant way would be to able to install the sweeping observer while the background job is running so it will expire all touched object's caches. Thinking further, sometimes from the Rails console, I'm starting manual imports by invoking MyModel.import_all! on the model that's going to import data. Now, how would caches be expired here? Clearly, the MVC way cannot work here. Time to break the rules. So, what would be the best approach to handle this? I'm seeing three ways with different downsides but only one that would solve the problem: 1. Expire fragments through observers the MVC way Downside: Background importers won't purge caches because only controllers install sweepers/observers. Conclusion: This is no option. 2. Expire fragments through observers installed in controllers and background jobs Downside: No sweeping when running imports from console. Conclusion: Probably the cleanest solution but not a real option. 3. Expire fragments directly from the models Downside: Not the proposed MVC way, no support in Rails framework. Conclusion: The only solution that works in a DRY way for me. Looking at these points, I question the whole design behind sweepers and their MVC voodoo. Trying to force cache sweeping into controllers only is somehow a failed design. I don't see why that is. In the end, it's the data that makes up the views. Why should a controller sweep its caches? Is it for performance reasons? Clearly it cannot be the choice about clearing its own views because other controllers could show results from the same models. I often end up purging the caches from all controllers within the observer. While that is DRY it shows the misconception about making sweepers available to controllers only. -- Replies to list only preferred. -- You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/rubyonrails-talk/32j75b-8bk.ln1%40hurikhan77.spdns.de. For more options, visit https://groups.google.com/d/optout.
