Create unique slug field in Django models.

unique_slug_django.py

def save(self, *args, **kwargs):
    self.do_unique_slug()
    super(Klass, self).save(*args, **kwargs)

def do_unique_slug(self):
    """
    Ensures that the slug is always unique for this post
    """
    if not self.id:
        # make sure we have a slug first
        if not len(self.slug.strip()):
            self.slug = slugify(self.title)

        self.slug = self.get_unique_slug(self.slug)
        return True

    return False

def get_unique_slug(self, slug):
    """
    Iterates until a unique slug is found
    """
    orig_slug = slug
    counter = 1

    while True:
        objects = Klass.objects.filter(slug=slug)
        if not objects.exists():
            return slug

        slug = "{}{}".format(orig_slug, counter)
        counter += 1