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 URL:s. How and when is this slug-thing supposed to be used?
(I have read it's definition in this glossary)
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).
It's a descriptive part of the URL that is there to make it more human descriptive, but without necessarily being required by the web server - in http://stackoverflow.com/questions/427102/in-django-what-is-a-slug the slug is 'in-django-what-is-a-slug', but the slug is not used to determine the page served (on this site at least)
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> LOL!!! What a loser heh </content>
<slug> the-46-year-old-virgin </slug>
Now let's pretend that we have a Django model such as:
class Article():
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 Article.id so the URL would look like this:
www.example.com/Article/23
Or, you could reference the title like so:
www.example.com/article/The 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:
www.example.com/article/The%2046%20Year%20Old%20Virgin
That's not solving our meaningful URL. Wouldn't this be better:
www.example.com/article/the-46-year-old-virgin
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!
As a bit of history, the term 'slug' comes from the world of newspaper editing.
It's the informal name given to a story during the production process. As the story winds its torturous path from beat reporter through to editor through to the "printing presses", this is the name it is referenced by, e.g., "Have you fixed those errors in the 'russia-cuts-europe-gas' story?".
Django uses it as part of the URL to locate the story, an example being www.mysite.com/archives/russia-cuts-europe-gas.
May I be complete to this, The term "slug" has to do with casting metal, lead, in this case, out of which the press fonts where made of. Every Paper then, had it's fonts factory, regularily, re-melted and recasted in fresh molds.Because after many prints they where worned out. Apprentice like me started their career there,and all the way to the top. (Not anymore) Typographs had to compose the text of the article in a backward manner with lead caracters stacked in a wise. So at printing time le letters would be straight on the paper. All typhographs could read the newspaper mirrored has fast has the printed one.Therefore the slugs,(like snails) also the slow stories(the lasts to be fixed) were many on the bench waiting, solely identified by their fist letters, mostly le whole title generaly 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-enthousiast-&-friendly-old-slug-boy-from-France.