Question

Is it typical to separate input validation from model-level validation in Django projects? For example, validating that a username fits naming criteria would be input validation, and verifying that the user isn’t already in the database would be model-level validation.

I’ve been looking at a co-worker’s code, and they put both types of validation in a form class (in forms.py). Is this the typical setup, or is it more common for the model-level validation to appear in the model or view?

Or is there a better way to be approaching this– such as using a ModelForm? I’m rather new to Django and trying to learn what is the recommended pattern for this situation.

Answer 1

This is a very interesting question (for me).

In my opinion, all validation code should be moved to model code. This is the way to not break business rules. When validation code is in the model it is not possible to forget some validation in a new form or to have inconsistent rules in several forms.

I link to you ‘Django, Raise a validation error in a model’s save method’ question that is related to yours. Below question you can see how move code validations from forms to model. I hope that this brief introduction can helps to you.

From what framework you come? How validation rules are writen in your enviromnent?