django:删除之前的照片，同时添加新照片

MEDIA_ROOT = os.path.join(BASE_DIR, 'media')

from django.db import models

class MyModel(models.Model):
    photo = models.ImageField(upload_to='photos/')

from django.shortcuts import render
from .models import MyModel

def upload_photo(request):
    if request.method == 'POST':
        # 获取之前的照片对象并删除
        previous_photo = MyModel.objects.get(id=request.POST['id'])
        previous_photo.photo.delete()
        previous_photo.delete()

        # 创建新的照片对象并保存
        new_photo = MyModel.objects.create(photo=request.FILES['photo'])

        return render(request, 'success.html')
    else:
        return render(request, 'upload.html')

<form method="post" action="{% url 'upload_photo' %}" enctype="multipart/form-data">
    {% csrf_token %}
    <input type="file" name="photo">
    <input type="submit" value="Upload">
</form>