Rails caching: replacement for expires_in on Rails.cache.fetch

Question

What's the best way to clear up this warning while keeping the brevity of the "get or set" caching call? I really like not having to do a get, then check for nil, then set...

# DEPRECATION WARNING: Setting :expires_in on read has been deprecated in favor of setting it on write.

@foo = Rails.cache.fetch("some_key", :expires_in => 15.minutes) do
    some stuff
end

Answer 1

I really like not having to do a get, then check for nil, then set...

Yes, you'll want to avoid doing that on every call, but you'll still have to do that at least once. Something simple like this may work for you:

def smart_fetch(name, options, &blk)
  in_cache = Rails.cache.fetch(name)
  return in_cache if in_cache
  val = yield
  Rails.cache.write(name, val, options)
  return val
end

Then in your views you can do:

@foo = smart_fetch("some_key") do
  some stuff
end

Note that the Rails cache store has a default expiry time you can set when you create it, so you may not need to override that on each call unless you need different expiry times.