Django. How add to form extra fields

forms.py

class MyForm(forms.Form):
    ...

    def __init__(self, *args, **kwargs):
        extra_fields = kwargs.pop('extra', 0)

        super().__init__(*args, **kwargs)
        if extra_fields and int(extra_fields) > 0:
            for index in range(int(extra_fields)):
                # generate extra fields in the number specified via extra_fields
                self.fields['my_field{index}'.format(index=index+1)] = \
                    forms.CharField()

views.py

    def get(self, request, *args, **kwargs):
        form = self.form_class(
            request.GET,
            extra=request.GET.get('extra_field_count', 0)
        )
        if form.is_valid():
            form_data = form.cleaned_data
            response = ...
            return JsonResponse(response, safe=False)
        else:
            return JsonResponse(form.errors)
        return super().get(request, *args, **kwargs)