Chained dropdown validation error. Form works - django

Question

Creating a chained drop down following a tutorial. Everything works fine but it is throwing an unnecessary validation error.
It is a basic 3 field form creating a person object with name, country and city.
Views.py
from django.shortcuts import render, redirect, get_object_or_404
from .forms import CustomerForm
from .forms import PersonCreationForm
from .models import Person, City
def store(request):
form = CustomerForm()
context = {'form': form}
return render(request, 'store/store.html', context)
def cart(request):
form = CustomerForm()
context = {'form': form}
return render (request, 'store/cart.html', context)
def checkout(request):
form = CustomerForm()
context = {'form': form}
return render(request, 'store/checkout.html', context)
def signup(request):
context = {}
return render(request, 'store/signup.html', context)
def home(request):
if request.method == 'POST':
form = CustomerForm(request.POST)
if form.is_valid():
pass # does nothing, just trigger the validation
else:
form = CustomerForm()
return render(request, 'shop.html', {'form': form})
def person_create_view(request):
form = PersonCreationForm()
if request.method =='POST':
form = PersonCreationForm(request.POST)
if form.is_valid():
form.save()
return redirect('person_add')
return render(request, 'store/ho.html', {'form': form})
def person_update_view(request, pk):
person = get_object_or_404(Person, pk = pk)
form = PersonCreationForm(instance = person)
if request.method == 'POST':
form = PersonCreationForm(request.POST, instance=person)
if form.is_valid():
form.save()
return redirect('person_change', pk = pk)
return render(request, 'store/ho.html', {'form': form})
#ajax
def load_cities(request):
country_id = request.GET.get('country_id')
cities = City.objects.filter(country_id = country_id)
return render(request, 'store/city_dropdown_list_options.html',{'cities':cities})
Forms.py
from django.forms import ModelForm
from .models import Customer, Person, City
from django import forms
class CustomerForm(ModelForm):
class Meta:
model = Customer
fields = '__all__'
class PersonCreationForm(forms.ModelForm):
class Meta:
model = Person
fields = '__all__'
def __init__(self, *args, **kwargs):
super().__init__(*args, **kwargs)
self.fields['city'].queryset = City.objects.none()
if 'country' in self.data:
try:
country_id = int(self.data.get('country'))
self.fields['city'].queryset = City.objects.filter(country_id = country_id)
except(ValueError, TypeError):
pass
elif self.instance.pk:
self.fields['city'].queryset = self.instance.country.city_set.order_by('name')
In forms.py line 14 where it says-
self.fields['city'].queryset = City.objects.none()
this line is throwing a validation error when I try to submit the form. In the tutorial they add the if/else argument and that solves the problem and error goes away.
error: "Select a valid choice. That choice is not one of the available choices"
In my case the error still shows up. If I ignore it and re select the city and submit, it works just fine.
It is almost like having a pause at that line and the system suddenly realizes that there is more code.
How do I fix this problem. Appreciate any help.