How to apply DRY to Django Models, forms

Question

I'm working on a website and simultaneously on a mobile app.

For the website I've created a Django Form for the User model which override the clean and valid_ methods to provide custom validation.

For the mobile app I'm doing a REST API which exposes and endpoint to create a new user using Tastypie for this.

My doubt is where and how should I define the custom validation for the User model applying the DRY principle.

I can create a UserForm from the data provided by the user in the mobile app, then use the method is_valid() for validating the data, but the form contains a password_confirm field which is also validated and in the app this field doesn't exist.

Should I create a UserForm specific for the mobile app? Should I move these validations to the model class?

Answer 1

The simplest way is probably to subclass the form. Create a LoginForm that does not have the password2 field, and use that one for the mobile login API. Then make a subclass called WebLoginForm and add a password2 field, as well as a clean_password2() method that includes the validation logic. That way, you won't even need to override any of your other clean() code.

An even easier--though hackish--solution would be to have the mobile app submit the password the user wrote both as "password1" and "password2" when it makes the API call.