I was implementing cache_fu for my upcoming application based on YouTube (will be premiered very soon here on my blog). I wanted to cache certain calls to the YouTube API to reduce the latency and the time mongrels got stuck waiting for the response. The first candidate to get cached was the “Top Rated Video” from YouTube. Since this section is a part of the homepage, I used fragment caching for it. Everything went fine, Memcached just ran so beautifully and the speed gain was exceptional. I added the :ttl option to the cache command to expire the contents, then suddenly nothing worked. Rails kept on whining for the cache helper call:
wrong number of arguments (2 for 1)
I checked and double-checked cache_fu source, and the fragment_cache.rb file in particular. I saw cache_fu extending the fragment cache helper with an extra hash argument to support the :ttl option. Why the hell I could not use it in my view?
It turned out that the fragment_cache overwrite in cache_fu was not called automatically. I had to manually added the call in environment.rb file to invoke the setup. Strange! It took me a while to figure out since I traced all source files in cache_fu to find the bug. I have to admit, cache_fu (previously known as acts_as_cached) has some kick-ass Ruby code written. I still need to learn a lot more about Ruby to get to that level of code craftsmanship.
To fix this issue, include this one line in your environment.rb file
ActsAsCached::FragmentCache.setup!
That will ensure the cache helper to have the :ttl option.