Django ModelForm: What is save(commit=False) used for?

Question

Why would I ever use save(commit=False) instead of just creating a form object from the ModelForm subclass and running is_valid() to validate both the form and model?

In other words, what is save(commit=False) for?

If you don't mind, could you guys provide hypothetical situations where this might be useful?

Answer 1

That's useful when you get most of your model data from a form, but you need to populate some null=False fields with non-form data.

Saving with commit=False gets you a model object, then you can add your extra data and save it.

This is a good example of that situation.