如何在CreateView中动态设置ForeignKey的初始值？

from django.views.generic.edit import CreateView
from .models import Parent, Child
from .forms import ChildForm

class ChildCreateView(CreateView):
    model = Child
    form_class = ChildForm
    template_name = 'child_create.html'

    def get_form_kwargs(self):
        kwargs = super().get_form_kwargs()
        parent_id = self.kwargs.get('parent_id')
        kwargs['initial'] = {'parent': parent_id}
        return kwargs

from django import forms

class ChildForm(forms.ModelForm):
    class Meta:
        model = Child
        fields = '__all__'

    def __init__(self, *args, **kwargs):
        initial = kwargs.get('initial', {})
        parent_id = initial.get('parent')
        if parent_id:
            self.fields['parent'].initial = parent_id
        super().__init__(*args, **kwargs)