Feature Request: Make ActiveRecord::Base#cache_key to accept timestamp column name(s) as argument and generate cache key

rubyonrails-core
1

Example:

Post.cache_key #=> posts/1-20140301093012
Post.cache_key(:created_at) #=> posts/1-20140216071232
Post.cache_key(:comments_update_at, :subscriptions_updated_at) #=> posts/1-20140228091114 (The latest of the two columns)

Would be great to add column type checking as well