How to create a unique slug in Django

Question

I am trying to create a unique slug in Django so that I can access a post via a url like this: http://www.example.com/buy-a-new-bike_Boston-MA-02111_2

The relevant models:

class ZipCode(models.Model):
    zipcode = models.CharField(max_length=5)
    city = models.CharField(max_length=64)
    statecode = models.CharField(max_length=32)

class Need(models.Model):
    title = models.CharField(max_length=50)
    us_zip = models.CharField(max_length=5)
    slug = ?????

    def get_city():
        zip = ZipCode.objects.get(zipcode=self.us_zip)
        city = "%s, %s %s" % (zip.city, zip.statecode, zip.zipcode)
        return city

A sample ZipCode record:

• zipcode = "02111"
• city = "Boston"
• statecode = "MA"

A sample Need record:

• title = "buy a new bike"
• us_zip = "02111"
• slug = "buy-a-new-bike_Boston-MA-02111_2" (desired)

Any tips as to how to create this unique slug? Its composition is:

• Need.title + "_" + Need.get_city() + "_" + an optional incrementing integer to make it unique. All spaces should be replaced with "-".

NOTE: My desired slug above assumes that the slug "buy-a-new-bike_Boston-MA-02111" already exists, which is what it has the "_2" appended to it to make it unique.

I've tried django-extensions, but it seems that it can only take a field or tuple of fields to construct the unique slug. I need to pass in the get_city() function as well as the "_" connector between the title and city. Anyone solved this and willing to share?

Thank you!

UPDATE

I'm already using django-extensions for its UUIDField, so it would be nice if it could also be usable for its AutoSlugField!

Answer 1

If you are thinking of using an app to do it for you, here is one.

https://github.com/un33k/django-uuslug

UUSlug = (``U``nique + ``U``code Slug)


Unicode Test Example
=====================
from uuslug import uuslug as slugify

s = "This is a test ---"
r = slugify(s)
self.assertEquals(r, "this-is-a-test")

s = 'C\'est déjà l\'été.'
r = slugify(s)
self.assertEquals(r, "c-est-deja-l-ete")

s = 'Nín hǎo. Wǒ shì zhōng guó rén'
r = slugify(s)
self.assertEquals(r, "nin-hao-wo-shi-zhong-guo-ren")

s = '影師嗎'
r = slugify(s)
self.assertEquals(r, "ying-shi-ma")


Uniqueness Test Example
=======================
Override your objects save method with something like this (models.py)

from django.db import models
from uuslug import uuslug as slugify

class CoolSlug(models.Model):
    name = models.CharField(max_length=100)
    slug = models.CharField(max_length=200)

    def __unicode__(self):
        return self.name

    def save(self, *args, **kwargs):
        self.slug = slugify(self.name, instance=self)
        super(CoolSlug, self).save(*args, **kwargs)

Test:
=====

name = "john"
c = CoolSlug.objects.create(name=name)
c.save()
self.assertEquals(c.slug, name) # slug = "john"

c1 = CoolSlug.objects.create(name=name)
c1.save()
self.assertEquals(c1.slug, name+"-1") # slug = "john-1"