如何使用post_delete - Django 1.8从文件系统中删除文件

Question

我有一个模型 - 产品,其中包含缩略图.我有另一个模型,其中包含与产品相关的图像 - ProductImage.我希望在删除产品实例时从服务器中删除缩略图和图像,有一段时间这似乎有效,但现在不行了.

相关代码......

Class Product(models.Model):
    title = Charfield
    thumbnail = ImageField(upload_to='thumbnails/', verbose_name='thumbnail', blank=True, )

Class ProductImage(models.Model):
    product = models.ForeignKey(plant, default=None, related_name='images')
    image = models.ImageField(upload_to='images/', verbose_name='image',)

以下删除方法(在产品类中)正在运行,但我更改了我的代码并且它不再有效 - 从我所读到的最佳做法是使用post_delete,而不是覆盖delete()

def delete(self):
    images = ProductImage.objects.filter(product=self)
    if images:
        for image in images:
            image.delete()
    super(Product, self).delete()

如何重写一个能实现我想要的删除方法？我曾尝试使用post_delete但到目前为止我一直没有成功,因为我不确定如何在删除ProductImage实例时应用它...

Answer 1

以下是一个例子post_delete:

import os
from django.db import models

def _delete_file(path):
   """ Deletes file from filesystem. """
   if os.path.isfile(path):
       os.remove(path)

@receiver(models.signals.post_delete, sender=ProductImage)
def delete_file(sender, instance, *args, **kwargs):
    """ Deletes image files on `post_delete` """
    if instance.image:
        _delete_file(instance.image.path)

@receiver(models.signals.post_delete, sender=Product)
def delete_file(sender, instance, *args, **kwargs):
    """ Deletes thumbnail files on `post_delete` """
    if instance.thumbnail:
        _delete_file(instance.thumbnail.path)

覆盖delete()方法:

class Product(models.Model):
    ...

    def delete(self):
        images = ProductImage.objects.filter(product=self)
        for image in images:
            image.delete()
        self.thumbnail.delete()
        super(Product, self).delete()


class ProductImage(models.Model):
    ...

    def delete(self):
        self.image.delete()
        super(ProductImage, self).delete()

阅读有关Cascade删除:docs的信息

Answer 2

在 1.11 Django 中。代码工作！

import os
from django.db import models
from django.utils import timezone

from django.db.models.signals import pre_delete
from django.dispatch.dispatcher import receiver

class Post(models.Model):
    category = models.ForeignKey(Category, verbose_name='?????????')
    title = models.CharField('?????????', max_length=200, unique=True)
    url = models.CharField('???', max_length=200, unique=True)
    photo = models.ImageField('???????????', upload_to="blog/images/%Y/%m/%d/", default='', blank=True)
    content = models.TextField('???????')
    created_date = models.DateTimeField('????', default=timezone.now)


def _delete_file(path):
    # Deletes file from filesystem.
    if os.path.isfile(path):
        os.remove(path)


@receiver(pre_delete, sender=Post)
def delete_img_pre_delete_post(sender, instance, *args, **kwargs):
    if instance.photo:
        _delete_file(instance.photo.path)