rjbs forgot what he was saying

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validation is now easy

by rjbs, created 2008-08-30 23:11
tagged with: @markup:md journal programming rx

Okay, the title might be a filthy lie, but it's just a reference to my previous posting about the fact that I couldn't find a single data validation system (read: schemata) for JSON-like data. I found plenty of schema languages for XML, one for YAML that was never going to be suitably cross-platform, and one for JSON (json-schema) that seemed over complicated and likely to become unmaintainable, and then some other things that don't warrant much mention.

I started sketching a system of my own on the flight back from OSCON, and it's been close to done for about two weeks now, while I make tweaks and apply some polish. I just finished committing what I hope is the final design change, and starting next week I hope to start making real, installable releases of the implementations.

I say "releases of the implementations" because there are five. I've implemented my schema system, called Rx, in Perl, Python, Ruby, PHP, and JavaScript. The test suite for Rx is a set of JSON files that define schemata and input data and provide expectations of what each schema should accept or reject. All you have to do to implement Rx in your language of choice is write something to load and run these tests. By way of example, the Ruby test program is about 2 kB, or 75 non-blank lines.

All of the implementations could use more documentation, polish, packaging, and refactoring. Each one was written in an evening, more or less, and then just tweaked as the design was tweaked.

I'll write much more about Rx as I polish it and begin using it more heavily. I have a lot of plans for add-on systems that will work in conjunction with Rx without impacting Rx's own simplicity.

In the meantime, you can read about what it can do, how it works, and how you can get a copy at the Rx web site.