Give a ForeignKey Form Field a value of a Queryset - django

Question

So I have two Models that I want to relate with a ForeignKey. One of the ModelForms I want to have it's Foreign Key field pre populated before the model gets created. The info from the ForeignKey comes from a ListView (List of Cars that belong to clients) template.
MODELS.PY
class ClientCar(models.Model):
license_plate = models.CharField(max_length=20, unique=True, name='license_plate')
def__str__:
pk = self.pk
license_plate = self.license_plate
return f"pk:{pk} license_plate {license_plate}"
class CarDetail(model.Model):
car = models.ForeignKey(ClientCar, on_delete=models.CASCADE, null=False)
detail = models.CharField(max_length=40, null=False)
So the ListView template will have the basic crud of the Car model but I also want to add a "Wash button", the wash button will pass the selected Car's pk to the CarDetail Form template. It is here where I am having issues. I can Query the PK of the car from Kwargs but I can't seem to populate the Form's field with that query or have it render on the template.
VIEWS.PY
class WashService(LoginRequiredMixin, CreateView):
model = CarDetail
form_class = WashServiceForm
template_name = 'service_app/standard_wash_form.html'
def get_form_kwargs(self, *args, **kwargs):
kwargs = super(WashService, self).get_form_kwargs(*args, **kwargs)
ctd = ClientCar.objects.filter(pk=self.kwargs.get('pk')).values('license_plate')
kwargs['initial']['car'] = ctd
return kwargs
I have researched this and came to the understanding that in the Form for creating this model I have to overwrite the _ _ init _ _ function, I'm not really sure how to solve this since I don't know how to call the kwargs passed from the Listview template from the forms.py
If you can guide me with some snippets or anything I'm greatful.
Thanks in advance.

Answer 1

I think it makes more sense to simply change what function the ModelChoiceField uses for the choices. We can first make a subclass of ModelChoiceField for the car, to select this by license plate:
from django import forms
class CarByLicensePlateChoiceField(forms.ModelChoiceField):
def label_from_instance(self, obj):
return obj.license_plate
Then in your WashServiceForm we can use this field:
class WashServiceForm(forms.ModelForm):
car = CarByLicensePlateChoiceField(queryset=Car.objects.all())
class Meta:
model = Car
fields = ['car', 'detail']
In your CreateView, you can then populate the car with the Car that belongs to the given primary key:
from django.shortcuts import get_object_or_404
class WashService(LoginRequiredMixin, CreateView):
model = CarDetail
form_class = WashServiceForm
template_name = 'service_app/standard_wash_form.html'
def get_form_kwargs(self, *args, **kwargs):
kwargs = super().get_form_kwargs(*args, **kwargs)
initials = kwargs.setdefault('initial', {})
intial['car'] = get_object_or_404(Car, pk=self.kwargs['pk'])
return kwargs