python - tutorial - django unique slug

What is a “slug” in Django? (6)


A short label for something, containing only letters, numbers, underscores or hyphens. They’re generally used in URLs. For example, in a typical blog entry URL: the last bit (spring) is the slug.

When I read Django code I often see in models what is called a "slug". I am not quite sure what this is, but I do know it has something to do with URLs. How and when is this slug-thing supposed to be used?

(I have read its definition in this glossary.)

Also auto slug at django-admin. Added at ModelAdmin:

prepopulated_fields = {'slug': ('title', )}

As here:

class ArticleAdmin(admin.ModelAdmin):
    list_display = ('title', 'slug')
    search_fields = ('content', )

    prepopulated_fields = {'slug': ('title', )}

From here.

“Slug” is a newspaper term, but what it means here is the final bit of the URL. For example, a post with the title, “A bit about Django” would become, “bit-about-django” automatically (you can, of course, change it easily if you don’t like the auto-generated slug).

If I may provide some historical context :

The term "slug" has to do with casting metal—lead, in this case—out of which the press fonts were made. Every paper then had its fonts factory regularly re-melted and recast in fresh molds, since after many prints they became worn out. Apprentices like me started their career there, and went all the way to the top (not anymore).

Typographs had to compose the text of an article in a backward manner with lead characters stacked in a wise. So at printing time the letters would be straight on the paper. All typographs could read the newspaper mirrored as fast as the printed one. Therefore the slugs, (like snails) also the slow stories (the last to be fixed) were many on the bench waiting, solely identified by their fist letters, mostly the whole title generally more readable. Some "hot" news were waiting there on the bench, for possible last minute correction, (Evening paper) before last assembly and definitive printing.

Django emerged from the offices of the Lawrence journal in Kansas. Where probably some printing jargon still lingers. A-django-enthusiast-&-friendly-old-slug-boy-from-France.

It's a way of generating a valid URL, generally using data already obtained. For instance, using the title of an article to generate a URL. I'd advise to generate the slug, using a function, given a title (or other piece of data), rather than setting it manually.

An example:

<title> The 46 Year Old Virgin </title>
<content> A silly comedy movie </content>
<slug> the-46-year-old-virgin </slug>

Now let's pretend that we have a Django model such as:

class Article(models.Model):
    title = models.CharField(max_length=100)
    content = models.TextField(max_length=1000)
    slug = models.SlugField(max_length=40)

How would you reference this object with a URL, with a meaningful name? You could use so the URL would look like this:

Or, you could reference the title like so: 46 Year Old Virgin

Problem is, spaces aren't valid in URLs, they need to be replaced by %20 which is ugly, making it the following:

That's not solving our meaningful URL. Wouldn't this be better:

That's a slug. the-46-year-old-virgin. All letters are downcased and spaces are replaced by hyphens -. See the URL of this very webpage for an example!

Slug is a URL friendly short label for specific content. It only contain Letters, Numbers, Underscores or Hyphens. Slugs are commonly save with the respective content and it pass as a URL string.

Slug can create using SlugField


class Article(models.Model):
    title = models.CharField(max_length=100)
    slug = models.SlugField(max_length=100)

If you want to use title as slug, django has a simple function called slugify

from django.template.defaultfilters import slugify

class Article(models.Model):
    title = models.CharField(max_length=100)

    def slug(self):
        return slugify(self.title)

If it needs uniqueness, add unique=True in slug field.

for instance, from the previous example:

class Article(models.Model):
    title = models.CharField(max_length=100)
    slug = models.SlugField(max_length=100, unique=True)

Are you lazy to do slug process ? don't worry, this plugin will help you. django-autoslug