I'm using CherryPy, Mako templates, and SQLAlchemy in a web app. I'm coming from a Ruby on Rails background and I'm trying to set up some data validation for my models. I can't figure out the best way to ensure, say, a 'name' field has a value when some other field has a value. I tried using SAValidation but it allowed me to create new rows where a required column was blank, even when I used validates_presence_of on the column. I've been looking at WTForms but that seems to involve a lot of duplicated code--I already have my model class set up with the columns in the table, why do I need to repeat all those columns again just to say "hey this one needs a value"? I'm coming from the "skinny controller, fat model" mindset and have been looking for Rails-like methods in my model like validates_presence_of or validates_length_of. How should I go about validating the data my model receives, and ensuring Session.add/Session.merge fail when the validations fail?
I ended up using WTForms after all.