Override delete method in django model-Python Tutorial-php.cn

Override delete method in django model

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Release： 2024-02-11 19:15:04

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重写 django 模型中的删除方法

Question content

I have a page model that calls print in the save method during saving of the object. However, when the object is deleted, no printing is triggered and the delete method never seems to be called. So how should I override the default delete method?

class Page(models.Model):
    image = models.ImageField()
    number = models.PositiveIntegerField(default=0, blank=True, null=True)
    chapter = models.ForeignKey(Chapter, on_delete=models.CASCADE)

    def get_upload_path(self, filename):
        work_slug = self.chapter.volume.work.slug
        translator_name = slugify(self.chapter.volume.translator)
        volume_number = self.chapter.volume.number
        chapter_number = self.chapter.number
        name, extension = filename.rsplit('.', 1)
        return f'media/{work_slug}/{translator_name}/volumes/volume-{volume_number}/chapters/chapter-{chapter_number}/page-{self.number}.{extension}'

    def save(self, *args, **kwargs):
        if not self.pk:
            last_page = self.chapter.page_set.last()
            if last_page:
                self.number = last_page.number + 1
        self.image.name = self.get_upload_path(self.image.name)
        self.image.storage = s3
        print(f"Saving Page with image: {self.image.name}")
        super().save(*args, **kwargs)

    def delete(self, *args, **kwargs):
        print(f"Deleting Page with image: {self.image.name}")

        image_name = self.image.name
        try:
            s3.delete(image_name)
            print(f"Successfully deleted from S3: {image_name}")
        except Exception as e:
            print(f"Error deleting from S3: {e}")

        super().delete(*args, **kwargs)

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Correct answer

Call the delete method of model when deleting an object. If you try to delete a queryset (e.g. from the django admin list page), you must overwrite the model's queryset.

class PageQuerySet(models.QuerySet):
    def delete(self):
        print("deleting queryset")
        return super().delete()


class PageManager(models.Manager):
    def get_queryset(self):
        return PageQuerySet(model=self.model, using=self._db, hints=self._hints)


class Page(models.Model):
    image = models.ImageField()
    number = models.PositiveIntegerField(default=0, blank=True, null=True)
    chapter = models.ForeignKey(Chapter, on_delete=models.CASCADE)

    objects = PageManager()

    def get_upload_path(self, filename):
        work_slug = self.chapter.volume.work.slug
        translator_name = slugify(self.chapter.volume.translator)
        volume_number = self.chapter.volume.number
        chapter_number = self.chapter.number
        name, extension = filename.rsplit('.', 1)
        return f'media/{work_slug}/{translator_name}/volumes/volume-{volume_number}/chapters/chapter-{chapter_number}/page-{self.number}.{extension}'

    def save(self, *args, **kwargs):
        if not self.pk:
            last_page = self.chapter.page_set.last()
            if last_page:
                self.number = last_page.number + 1
        self.image.name = self.get_upload_path(self.image.name)
        self.image.storage = s3
        print(f"Saving Page with image: {self.image.name}")
        super().save(*args, **kwargs)

    def delete(self, *args, **kwargs):
        print(f"Deleting Page with image: {self.image.name}")

        image_name = self.image.name
        try:
            s3.delete(image_name)
            print(f"Successfully deleted from S3: {image_name}")
        except Exception as e:
            print(f"Error deleting from S3: {e}")

        super().delete(*args, **kwargs)

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