How to delete files from filesystem using post_delete - Django 1.8

Question

I have a model - Product, which contains a thumbnail image. I have another model which contains images associated with the product - ProductImage. I want to delete both the thumbnail and the images from the server when the product instance is deleted, and for a while this seemed to worked, but not anymore.

Relevant code...

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',)

The following delete method (in the product class) was working, but I changed my code and it no longer works - and from what i have read it is best practice to use post_delete, rather then override delete()

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

How can I rewrite a delete method which will achieve what I want? I have tried to use post_delete but so far I have been unsuccessful because I am not sure how to apply it when it comes to deleting the ProductImage instance...

Answer 1

And here's an example with the 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)

Overriding the delete() method:

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()

Read about Cascade delete: docs

Answer 2

In 1.11 Django. Code work!

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='Категория')
    title = models.CharField('Заголовок', max_length=200, unique=True)
    url = models.CharField('ЧПУ', max_length=200, unique=True)
    photo = models.ImageField('Изображение', upload_to="blog/images/%Y/%m/%d/", default='', blank=True)
    content = models.TextField('Контент')
    created_date = models.DateTimeField('Дата', 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)