Fixed #21936 -- Allowed DeleteView to work with custom Forms and SuccessMessageMixin.

[carltongibson]

Alternate to #13362, building on @demestav's PR there.

ticket-21936

[auvipy]

AFAIK this PR was based on more latest suggestions https://github.com/django/django/pull/5992/files you could check

[carltongibson]

@auvipy This PR is based on @demestav's work in #13362, which was originally based on @cpsimpson's work in #2585.

I've used the test cases from #13362 directly (with minor edits), but changed the implementation in django/views/generic/edit.py to address the various concerns raised over the years.

#5992 wasn't even looked at until you mentioned it. Looking now it seems to be based entirely on #2585, but didn't address the review comments, which is OK, time is limited, but presumably why you never pushed it to conclusion.

[felixxm]

@carltongibson Thanks 👍 I left small comments.

[felixxm]

I wonder if it makes sense to add a hook (with better name) that could be called here and in DeletionMixin:

class DeletionMixin:
    ...

    def _delete(self):
        if not getattr(self, 'object', None):
            self.object = self.get_object()
        success_url = self.get_success_url()
        self.object.delete()
        return HttpResponseRedirect(success_url)

    def delete(self, request, *args, **kwargs):
        return self._delete()

class BaseDeleteView(DeletionMixin, FormMixin, BaseDetailView):
    ...
    def form_valid(self, form):
        return self._delete()    

[carltongibson]

Yeah... I could go either way here. At what point is it easier just to read it in place than go look for it in another class? (There's no definite answer there I think.)

[felixxm]

Agreed, the current form is more readable.

[carltongibson]

OK, super. Thanks — I didn't change it 😄

(My overriding feeling is that we have enough hooks already here, and than this one wouldn't ever be used anywhere...)

But 👍 Thanks.