如何在Django表单集中更新多个实例的外键

from django import forms
from .models import Child

class ChildForm(forms.ModelForm):
    parent = forms.ModelChoiceField(queryset=Parent.objects.all())

    class Meta:
        model = Child
        fields = ['parent']

from django.shortcuts import render
from .forms import ChildForm

def update_children(request):
    children = Child.objects.all()
    formset = ChildFormSet(queryset=children)

    if request.method == 'POST':
        formset = ChildFormSet(request.POST, queryset=children)
        if formset.is_valid():
            formset.save()
            # 更新成功后的操作

    return render(request, 'update_children.html', {'formset': formset})

<!-- update_children.html -->
<form method="post">
  {% csrf_token %}
  {{ formset.management_form }}
  {% for form in formset %}
    {{ form.as_table }}
  {% endfor %}
  <input type="submit" value="保存">
</form>