Hi Mikhail,
On Apr 24, 7:46 am, Mikhail Korobov <kmik...@googlemail.com> wrote:
> The issue is not only with unique_together indeed. Please correct me if I'm
> wrong, but it seems there is no way currently to use model validation with
> fields dependent on each other when one of these fields is not POSTed
> directly by user. Example:
>
> # models.py
> class Ticket(models.Model):
> created_by = models.ForeignKey(User, related_name='created_tickets')
> responsible = models.ForeignKey(User, related_name='todo')
>
> def clean():
> # we don't want to allow tickets where created_by == responsible for
> some reason
> from django.core.exceptions import ValidationError
> if self.created_by == self.responsible:
> raise ValidationError('Responsible is incorrect.')
>
> # views.py
> class TicketForm(forms.ModelForm):
> class Meta:
> model = Ticket
> exclude = ['created_by']
>
> @login_required
> def add_ticket(request):
> form = TicketForm(request.POST or None)
> if form.is_valid():
> ticket = form.save(commit=False)
> ticket.created_by = request.user
>
> # todo: handle ticket.full_clean()
>
> ticket.save()
> return redirect('ticket_list')
> return TemplateResponse(request, 'tickets/add.html', {'form': form})
>
> Model.clean method is always called on form validation (unlike field
> validators that are excluded if field is excluded from form). And we can't
> write validator for 'responsible' field or for 'created_by' field (so that
> it will be excluded from validation on form.is_valid) because this validator
> won't have an access to other model fields. So the only option here seems to
> move validation from model level to form level.
>
> Please consider this use case while rethinking model validation. The
> proposed context manager seems to be a very good idea and I hope it will fix
> this issue as well.
Sorry, I missed this somehow earlier. I agree with you that this is
another example of why attempting to do partial model validation is
simply broken. I think the context manager proposal (which I've posted
in a new thread) does fix this case as well, and I'd be happy for your
comments on it.
Carl
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