Feature Request: unique validation in schema

[robnoake]

Enforcing a unique constraint involves setting up a callback inside of model at present, it would be nice to be able to express this in the schema definition.

[serby]

This would be nice. Unfortunately it is hard to achieve without coupling the schema tightly to the model which is something I've been trying to avoid or doing it outside of the validation mechanism that already exists.

It will get added at some point but the architecture eludes me at present.