inlineformset_factory minimal required - django

Question

Using inlineformset_factory I am able to add / remove phone numbers related to a single customer. Only problem is, I want to require at least 1 valid phone number for each customer.
Here is some demo code:
Models:
class Customer( models.Model ):
name = models.CharField( max_length=255 )
class PhoneNumber( models.Model ):
customer = models.ForeignKey( Customer )
number = models.CharField( max_length=10 )
Forms:
class CustomerForm( ModelForm ):
class Meta:
model = Customer
fields = ['name']
class PhoneNumberForm( ModelForm ):
class Meta:
model = PhoneNumber
fields = ['number']
Ok, so that's pretty straight forward.
Then in my view:
class Create( View ):
template_name = 'path_to_template'
CustomerForm = forms.CustomerForm
PhoneNumberFormSet = inlineformset_factory (
parent_model = Customer,
model = PhoneNumber,
form = PhoneNumberForm,
extra = 1,
)
def get(self, request):
# Return empty forms
context = {
'customer_form': self.CustomerForm,
'phone_number_formset': self.PhoneNumberFormSet
}
render( request, self.template_name, context)
def post(self, request):
this_customer_form = self.CustomerForm( request.POST )
if this_customer_form.is_valid():
new_customer.save(commit=False)
this_phone_number_formset = self.PhoneNumberFormSet(request.POST, instance=new_customer)
if this_phone_number_formset.is_valid():
new_customer.save()
this_phone_number_formset.save()
return HttpResponseRedirect(reverse_lazy('customer-detail', kwargs={'pk': new_customer.pk}))
# Something is not right, show the forms again
this_phone_number_formset = self.PhoneNumberFormSet(request.POST)
context = {
'customer_form': this_customer_form,
'phone_number_formset': this_phone_number_formset
}
render( request, self.template_name, context)
You get the point I think. Same thing for the Edit/Update view of the customer. Only then the forms are prepopulated.
At this point all I need is a way to require at least 1 valid PhoneNumber per Customer.
I found something like:
class RequiredFormSet(BaseFormSet):
def __init__(self, *args, **kwargs):
super(RequiredFormSet, self).__init__(*args, **kwargs)
for form in self.forms:
form.empty_permitted = False
from https://stackoverflow.com/questions/2406537/django-formsets-make-first-required
but it doesnt seem to work when I apply this on a BaseInlineFormSet class.
Django 1.7 seems to answer my wishes, but not for a InlineModelFormSet so far..
Any ideas?

Answer 1

If you just want to set the minimum or maximum, you can set them directly in inlineformset_factory, here's my code for minimum of one entry
from django.forms import inlineformset_factory
SubUnitFormSet = inlineformset_factory(
Unit, SubUnit, form=SubUnitForm, min_num=1, validate_min=True, extra=0)
You need to properly handle this in your view. I'm using CBV and this is my code for your reference
class UnitCreateView(PermissionRequiredMixin, SuccessMessageMixin, CreateView):
permission_required = "core.add_unit"
model = Unit
form_class = UnitForm
template_name = 'core/basic-info/unit_form.html'
success_url = reverse_lazy('core:units')
success_message = _("%(code)s was added successfully")
def get_context_data(self, **kwargs):
data = super(UnitCreateView, self).get_context_data(**kwargs)
if self.request.POST:
data['subunits'] = SubUnitFormSet(self.request.POST, )
else:
data['subunits'] = SubUnitFormSet()
return data
def form_valid(self, form):
context = self.get_context_data()
subunits = context['subunits']
with transaction.atomic():
if subunits.is_valid():
self.object = form.save()
subunits.instance = self.object
subunits.save()
else:
return self.render_to_response(self.get_context_data(form=form))
return super(UnitCreateView, self).form_valid(form)

Answer 2

Thank you kezabella ( django irc ).
Seems I found a solution by subclassing BaseInlineFormset:
class RequiredFormSet(BaseInlineFormSet):
def clean(self):
for form in self.initial_forms:
if not form.is_valid() or not (self.can_delete and form.cleaned_data.get('DELETE')):
return
for form in self.extra_forms:
if form.has_changed():
return
raise ValidationError("No initial or changed extra forms")
Btw, these validation errors do not show up in {{ formset.error }} but in:
{{ formset.non_form_errors }}