data validation for SQLAlchemy declarative models

Take a look at the documentation for adding validation methods. You could just add an "update" method that takes the POST dict, makes sure that required keys are present, and uses the decorated validators to set the values (raising an error if anything is awry).

I wrote SAValidation for the specific purpose of avoiding code duplication when it comes to validating model data. It works well for us, at least for our use cases.

In our tests, we have examples of the model's setup and tests to show the validation works.