How do I create a slug in Django?

Question

I am trying to create a SlugField in Django.

I created this simple model:

from django.db import models

class Test(models.Model):
    q = models.CharField(max_length=30)
    s = models.SlugField()

I then do this:

>>> from mysite.books.models import Test
>>> t=Test(q="aa a a a", s="b b b b")
>>> t.s
'b b b b'
>>> t.save()
>>> t.s
'b b b b'

I was expecting b-b-b-b.

Answer 1

In most cases the slug should not change, so you really only want to calculate it on first save:

class Test(models.Model):
    q = models.CharField(max_length=30)
    s = models.SlugField(editable=False) # hide from admin

    def save(self):
        if not self.id:
            self.s = slugify(self.q)

        super(Test, self).save()

Answer 2

If you're using the admin interface to add new items of your model, you can set up a ModelAdmin in your admin.py and utilize prepopulated_fields to automate entering of a slug:

class ClientAdmin(admin.ModelAdmin):
    prepopulated_fields = {'slug': ('name',)}

admin.site.register(Client, ClientAdmin)

Here, when the user enters a value in the admin form for the name field, the slug will be automatically populated with the correct slugified name.

Answer 3

You will need to use the slugify function.

>>> from django.template.defaultfilters import slugify
>>> slugify("b b b b")
u'b-b-b-b'
>>>

You can call slugify automatically by overriding the save method:

class Test(models.Model):
    q = models.CharField(max_length=30)
    s = models.SlugField()

    def save(self, *args, **kwargs):
        self.s = slugify(self.q)
        super(Test, self).save(*args, **kwargs)

Be aware that the above will cause your URL to change when the q field is edited, which can cause broken links. It may be preferable to generate the slug only once when you create a new object:

class Test(models.Model):
    q = models.CharField(max_length=30)
    s = models.SlugField()

    def save(self, *args, **kwargs):
        if not self.id:
            # Newly created object, so set slug
            self.s = slugify(self.q)

        super(Test, self).save(*args, **kwargs)