Anyone who’s designed a Flex application built on LiveCycle Data Services knows the love-hate relationship that comes with it.

But regardless of the effort, no one can deny that managed collections kick some serious ass. With paging enabled, you can access datasets with hundreds of thousands of items one page-at-a-time, thereby reducing server load and avoiding a UI-rendering black hole.

However, this comes at a price. You no longer have immediate access to all of the data in your collection, although it certainly seems like you do. Iterate through the collection once, and you’ve ruined all the benefits paging was designed to offer you.

LCDS Tip #1: NEVER iterate through a managed collection!

How does this affect sorts and filters applied to your collection? The Flex implementations of ICollectionView retrieve all the items from a destination before executing a sort or filter.

That’s the rub. Apply a sort or filter to your collection, and paging is out the door. Which kind of defeats the purpose of using LCDS to begin with.

Or does it?

You could of course include the sort or filter criteria in the signature for your destination, but even that’s an unnecessary step. If you simply apply a sort or filter BEFORE you perform the fill, LCDS will know what you’re trying to do and will happily return paged data that is sorted and/or filtered.

How’s that for awesome?

So long as you don’t need to change the sort or filter criteria after the fill, you’re in the clear. And if you do have a variable sort or filter you can, like I mentioned above, simply release your collection, re-apply the sort or filter, and then perform the fill again.

I knew I loved LCDS. 😉

Advertisements