As part of a project I’ve been working on for a client, we’ve decided to implement HTTP PATCH in our API for making changes. The main client consuming the API is a web application driven by Knockout.JS, so this meant we had to find a way to figure out what had changed on our view model, and then send just those values over the wire.

There is nothing new or exciting about this requirement in itself. The question has been posed before  and it was the subject of a blog post way back in 2011 by Ryan Niemeyer. What was quite exciting however was that our solution ended up doing much more than just detect changes to viewmodels. We needed to keep tabs on individual property changes, changes to arrays (addsdeletesmodifications), changes to child objects and even changes to child objects nested within arrays. The result was a complete…