如何通过Django模型表单插入外键数据

from django.db import models

class ChildModel(models.Model):
    name = models.CharField(max_length=50)

class ParentModel(models.Model):
    child = models.ForeignKey(ChildModel, on_delete=models.CASCADE)
    # 其他字段...

from django import forms
from .models import ParentModel

class ParentModelForm(forms.ModelForm):
    class Meta:
        model = ParentModel
        fields = '__all__'

from django.shortcuts import render, redirect
from .forms import ParentModelForm

def create_parent(request):
    if request.method == 'POST':
        form = ParentModelForm(request.POST)
        if form.is_valid():
            parent = form.save(commit=False)
            # 获取外键模型的实例
            child_id = request.POST.get('child')
            child = ChildModel.objects.get(id=child_id)
            # 将外键字段与外键模型关联
            parent.child = child
            parent.save()
            return redirect('success')  # 保存成功后的跳转页面
    else:
        form = ParentModelForm()
    return render(request, 'create_parent.html', {'form': form})

<form method="POST">
  {% csrf_token %}
  {{ form.as_p }}
  <button type="submit">保存</button>
</form>