Formset's validate_min doesn't work correctly with empty forms

[Wim Feijen]

validate_min and min_num do not behave as I expected.

Defining a formset like this:

ImageFormSet = inlineformset_factory(
    Room,
    Image,
    form = ImageForm,
    extra = 5,
    min_num = 1,
    max_num = 5,
    validate_min = True,
)

...
        image_formset = ImageFormSet(request.POST, request.FILES, instance=room)

I filled in image_formset with this data. Note that I am posting one form with data and four empty forms.

(Pdb) image_formset.cleaned_data
[{'image': <InMemoryUploadedFile: gras.jpg (image/jpeg)>, 'room': <Room: Test wim yy>, u'id': None, u'DELETE': True}, {}, {}, {}, {}]

Due to the empty forms, this passes validation, contrary to my expectations.

This is because of:
lines 354 and 355 in django/forms/formsets.py

            if (self.validate_min and
                    self.total_form_count() - len(self.deleted_forms) < self.min_num):

and

(Pdb) image_formset.total_form_count()
5

total_form_count() turns out to be 5 instead of 1 .

[Tim Graham]

​PR

[Tim Graham]

The issue here turns out to be empty forms be included in the form count.

[Tim Graham <timograham@…>]

In f5c6295:

Fixed #26844 -- Made formset's validate_min validation ignore empty forms.

[Jim Ouwerkerk]

Replying to Tim Graham <timograham@…>:

In f5c6295:

Fixed #26844 -- Made formset's validate_min validation ignore empty forms.

This commit breaks the validate_min validation for formset with existing unchanged data in Django 1.11.
It counts unchanged existing forms as 'empty' form because they are not changed, but they should not be counted as empty.

[Simon Charette]

Jim, please file a new ticket instead of reopening this one. Just make sure to refer to this ticket to provide context.

[Tim Graham]

The new ticket is #28130.