Duplicate saves in TurboCreateView

[davidkell]

After debugging, we noticed that the form is saved twice in TurboCreateView.

Relevant source code:

# mixins.py
class TurboFormModelMixin(TurboFormMixin):

    object: Optional[Model]

    def form_valid(self, form: forms.Form) -> HttpResponse:
        """If the form is valid, save the associated model."""
        self.object = form.save()
        return super().form_valid(form)

# views.py

class TurboCreateView(TurboFormModelMixin, CreateView):
    ...

But the Django CreateView already uses the ModelFormMixin with:

def form_valid(self, form):
    """If the form is valid, save the associated model."""
    self.object = form.save()
    return super().form_valid(form)

The result is that form.save() is called twice.

I think the fix is:

class TurboCreateView(TurboFormMixin, CreateView):
    ...
```

Ditto `TurboUpdateView`. Thoughts?

[danjac]

I haven't used the CBVs myself so that might well be the case.

I'd be happy to accept a PR. Key is that the view should return the correct response status (e.g. 303 redirect if successful).