Why is the parent record removed?

Question

Django

Hello everyone once again)

I have a model:

class NewModel(models.Model):
    id = models.AutoField(primary_key=True)
    creator = models.ForeignKey(Users, on_delete=models.CASCADE, related_name='created', verbose_name='Owner')
    avatar = models.ForeignKey(Avatar, on_delete=models.CASCADE, null=True, default=None)
    video = models.ForeignKey(AvatarVideo, on_delete=models.CASCADE, null=True, default=None)

    def set_avatar(self, image):
            if self.avatar is not None:
                self.avatar.delete()
            self.avatar = Avatar.upload_image(image=image, owner_type='marathon', picture_type='avatar')
            self.save()
    
    def set_video(self, video):
            if self.video is not None:
                self.video.delete()
            self.video = AvatarVideo.upload_video(video=video, owner_type='marathon', video_type='avatar-video')
            self.save()

Table AvatarVideo:

class AvatarVideo(models.Model):
    local_url = models.FileField(upload_to=upload_to)
    url_to_upload = models.CharField(max_length=200, default='')

    class Meta:
        verbose_name = "Avatars.Video"
        verbose_name_plural = "Avatars.Videos"

    @staticmethod
    def upload_video(video, owner_type, video_type):
        video_name = AvatarVideo.get_uuid_name_with_extension(video)
        video = AvatarVideo.objects.create(
            local_url=video,
            url_to_upload=Uploader.get_path(owner_type, video_type, video_name)
        )
        return video

    def delete(self, using=None, keep_parents=True):
        os.remove(self.url_to_upload)
        super().delete(using=using, keep_parents=keep_parents)

    @staticmethod
    def get_uuid_name_with_extension(video):
        video = pathlib.Path(video.name).suffix
        uuid_name = uuid.uuid4()
        return f'{uuid_name}{video.lower()}'

When the def delete function is called, which should delete the instance and file from the system, it also deletes the entry in NewModel, to which the AvatarVideo entry itself belongs.

P.S.
I thought that the problem was in keep_parents - I set both True and False, but nothing has changed.

Answer 1

You specify for ForeignKey models.CASCADE, so it removes all related records. Set models.SET_NULLor models.DO_NOTHING, depending on what kind of database behavior you want to get when deleting related records...
Documentation: https://djbook.ru/rel3.0/ref/models/fields.html#ar...