gistfile1.py

from django.db import models

from django.contrib.contenttypes.models import ContentType
from django.contrib.contenttypes import generic

# Create your models here.

class Barcode(models.Model):
    """ A barcode can be thought of a real world generic foreign key that points to an object somewhere in the DB """

    code = models.CharField(max_length=128, unique=True, blank=False)

    content_type = models.ForeignKey(ContentType, blank=True, null=True)
    object_id = models.PositiveIntegerField(blank=True, null=True)
    content_object = generic.GenericForeignKey(ct_field='content_type', fk_field='object_id', null=True)
    created = models.DateTimeField(auto_now_add=True)

    def __unicode__(self):
        # This will get slow when viewing a large list of barcodes.
        return "<Barcode: %s> [%s.%s] %s" % (self.code, self.content_type.app_label, self.content_object.__class__.__name__, self.content_object)