gistfile1.py

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

class FileAttachment(models.Model):
    content_type = models.ForeignKey(ContentType, related_name="content_type_timelines")
    object_id = models.PositiveIntegerField()
    content_object = GenericForeignKey('content_type', 'object_id')
    created = models.DateTimeField(_('created'), auto_now_add=True)
    modified = models.DateTimeField(_('modified'), auto_now=True)
    attachment_file = models.FileField(_('attachment'), upload_to=attachment_upload)