I am trying to add validation to my Django forms.
I want to require at least one child model for my inlineformset.
I am using the following as a reference: Inline Form Validation in Django
I am still getting an error
line 454, in formset_factory return type(form.name + str('FormSet'), (formset,), attrs) TypeError: metaclass conflict: the metaclass of a derived class must be a (non-strict) subclass of the metaclasses of all its bases
from django.forms import inlineformset_factory
from .models import *
from django.forms.models import BaseInlineFormSet
from django import forms
class PropertyForm(forms.ModelForm):
class Meta:
model = Property
exclude = ()
class UnitForm(forms.ModelForm):
class Meta:
model = Unit
exclude = ()
class CustomUnitFormset(BaseInlineFormSet):
def is_valid(self):
return super(CustomUnitFormset, self).is_valid() and \
not any([bool(e) for e in self.errors])
def clean(self):
# get forms that actually have valid data
count = 0
for form in self.forms:
try:
if form.cleaned_data and not form.cleaned_data.get('DELETE', False):
count += 1
except AttributeError:
pass
if count < 1:
raise forms.ValidationError('You must have at least one unit')
UnitFormSet = inlineformset_factory(Property, Unit, form=PropertyForm,
formset='CustomUnitFormset',
extra=0,
min_num=1,
validate_min=True,
validate_max=True,
max_num=10,
)
view.py
class PropertyUnitCreate(LoginRequiredMixin, CreateView):
model = Property
fields = ['address']
success_url = reverse_lazy('property-list')
def get_context_data(self, **kwargs):
data = super(PropertyUnitCreate, self).get_context_data(**kwargs)
if self.request.POST:
data['units'] = UnitFormSet(self.request.POST)
else:
data['units'] = UnitFormSet()
return data
def form_valid(self, form):
context = self.get_context_data()
units = context['units']
form.instance.user = self.request.user
with transaction.atomic():
self.object = form.save()
if units.is_valid():
units.instance = self.object
units.save()
return super(PropertyUnitCreate, self).form_valid(form)
I have also tried to understand the inheritance issues explained here:Triple inheritance causes metaclass conflict... Sometimes
My view logic comes from https://medium.com/@adandan01/django-inline-formsets-example-mybook-420cc4b6225d
But I dont see where i have a class inheriting from two classes that would cause this error. Everything works fine if i remove the " formset='CustomUnitFormset', "
Can someone explain the reason for the error and how i could prevent this? Could i be managing my forms.py file better?
