Rails.cache.clear certain key names?

Question

Is it possible to somehow run Rails.cache.clear and only clear keys with a certain name/string?

I don't want to clear the entire cache...just keys with the string blog/post in the name (ie. blog/post/1, blog/post/2).

I'm using dalli with memcached for my cache and running Rails 3.0.6.

Colecolectomy

Answer 1

To answer my own question...it seems that given I'm using memcached, I actually can't use delete_if or delete_matched because memcached does not support enumerating or querying keys by pattern (1).

Colecolectomy

So, What is the solution while using memcache ? – Vachill

Answer 2

This is how you can write to cache -

Rails.cache.write('key', 'value', :time_to_idle => 60.seconds, :timeToLive => 600.seconds)

and in order to delete from cache you can use delete action -

Rails.cache.delete('key')

Delete multiple keys -

Rails.cache.delete_if {|k, v| k =~ 'key' }

Cardboard

Right, but I need to delete all keys that contain a certain string in their name. For instance, all keys that have blog/post in the name of the key. – Colecolectomy

@Colecolectomy Rails.cache is just a hash ..look for the hash documentation in order to delete multiple keys :) – Cardboard

I'm geting an 'undefined method' error for delete_if. I'm running Rails 3.0.6. – Colecolectomy

Also, forgot to mention, I'm using Dalli w/ memcached as my cache. – Colecolectomy

time to idle and time to live seems for EH cache only guides.rubyonrails.org/… – Taliataliaferro

Answer 3

You can use the https://github.com/Phobos98/dalli-delete-matched gem that adds a simple implementation of delete_matched method for dalli store with memcached.

Wineglass

Does that work in a multi-server environment? The gem looks like it stores the keys on the cache server without any guards to prevent multiple writers – Antagonistic

Answer 4

I add some dependency in the cache key, for example Rails.cache.fetch("blog_#{blog.posts.order(:id).last.updated_at}_stat"). So this key will expire automatically when any post changed.

Chenay