如何在django中更新一个表单中的两个模型？

# forms.py
from django import forms
from .models import Model1, Model2

class MyForm(forms.ModelForm):
    class Meta:
        model = Model1
        fields = ['field1', 'field2']

# views.py
from django.shortcuts import render, get_object_or_404
from .forms import MyForm
from .models import Model1, Model2

def update_form(request, pk):
    instance = get_object_or_404(Model1, pk=pk)
    form = MyForm(request.POST or None, instance=instance)

    if request.method == 'POST':
        if form.is_valid():
            form.save()
            # 更新第二个模型
            model2_instance = get_object_or_404(Model2, pk=pk)
            model2_instance.field3 = form.cleaned_data['field1']
            model2_instance.field4 = form.cleaned_data['field2']
            model2_instance.save()
            return redirect('success_url')

    return render(request, 'update_form.html', {'form': form})