JourneyJoker/gallery/models.py

from django.db import models
from django.contrib.contenttypes.fields import GenericForeignKey
from django.contrib.contenttypes.models import ContentType

from .helpers import get_upload_path

class Image(models.Model):
    image = models.ImageField(upload_to=get_upload_path)
    title = models.CharField(max_length=128, null=True, blank=True)
    comment = models.TextField(null=True, blank=True)

    content_type = models.ForeignKey(ContentType, on_delete=models.CASCADE)
    object_id = models.PositiveIntegerField()
    content_object = GenericForeignKey('content_type', 'object_id')

    upload_path = models.CharField(max_length=256, null=True, blank=True)

    @property
    def url(self):
        return self.image.url