Generating unique slugs with Django

Posted: Sun 15 July 2012

Tagged as:

Django

This is something I've come across a couple of times over the last few months and each time ended up acking through various projects so putting this up here to save myself the pain next time!

There are two versions to this method - model specific and a more generic one intended for a utils module if you're going to use it on more than one model.

Neither of these methods is built to scale, but since I've never worked at scale this hasn't been an issue. However you've been warned!

The functions make the slug unique by appending a count to the end and checking the length is still valid for the slug field.

Model Specific

from django.template.defaultfilters import slugify @classmethod def generate_slug(self, name): count = 1 slug = slugify(name) def _get_query(slug): if MyModel.objects.filter(slug=slug).count(): return True while _get_query(slug): slug = slugify(u'{0}-{1}'.format(name, count)) # make sure the slug is not too long while len(slug) > MyModel._meta.get_field('slug').max_length: name = name[:-1] slug = slugify(u'{0}-{1}'.format(name, count)) count = count + 1 return slug

example usage: MyModel.objects.create(name='foo', slug=MyModel.generate_slug('foo'))

Generic

from django.template.defaultfilters import slugify def generate_slug(cls, value): count = 1 slug = slugify(value) if not isinstance(cls, type): cls = cls.__class__ def _get_query(cls, **kwargs): if cls.objects.filter(**kwargs).count(): return True while _get_query(cls, slug=slug): slug = slugify(u'{0}-{1}'.format(value, count)) # make sure the slug is not too long while len(slug) > cls._meta.get_field('slug').max_length: value = value[:-1] slug = slugify(u'{0}-{1}'.format(value, count)) count = count + 1 return slug

example usage: AnotherModel.objects.create(name='bar', slug=generate_slug(AnotherModel, 'foo'))