Shared Object gotchas

If you don't understand how something works, bugs will ensue.

Experience is what you get when you don't get what you want.

I've got a zillion of these sayings.

Anyway.

The SharedObject is a Flash-cookie way to cache data locally. If one's not there when you reference it, it's created, automagically, in memory until you flush it to disk.

Here's the fun part. We have persisted data that goes stale regularly, and we want to test our caches to make sure they're fresh. We have a GUID for general tests, but we also just test to see if the cache "exists"... and that's a problem. How do you know a cache "exists" if it's created the first time you look at it?

Our fix is to check the object's size. If its size is 0 (zero), then it was just created and doesn't in fact "exist". Therefore we know to go to the database to fetch our data.