Filter a Django form select element based on a previously selected element

Question

Let\'s consider the following models

models.py

Class Brand(models.Model):
    company_name = models.CharField(max_length=100)


class CarModel(models.Model         


        

Answer 1

class Country(models.Model):
   country_name=models.CharField(max_length=10, blank=True, null=True)

class State(models.Model):
   state_name=models.CharField(max_length=10, blank=True, null=True)

class MyCustomModal(models.Model):
   country = models.ForeignKey(Country, on_delete=models.CASCADE, null=True, blank=True)
   state = models.ForeignKey(State, on_delete=models.CASCADE, null=True, blank=True)

Here is my Form

class MyCustomForm(forms.ModelForm):
    class Meta:
        model = MyCustomModal
        fields = [
            'country',
            'state',           
        ]        

    def __init__(self, *args, **kwargs):
        super(MyCustomForm, self).__init__(*args, **kwargs)        
        self.fields['country'] = forms.ChoiceField(choices=[('1','india'),('2','US')])
        self.fields['state'].queryset = State.objects.filter(pk=2)