if you want to use something more standards-compliant, I have this library which does compile-time generation of strictly validation functions from Jsonschemas:
It doesn’t normalize your parameters, though, so if you need a translation layer between things with different “names” (e.g. camelCase → snake_case) you might have to cook up something on your own. We do this at work with a “Codec” module which I may do a webcast on sometime.
With Ecto, though, you can just peddle in strings and it figures out the pesky strings/atoms stuff for you.
