Django: formats of urlpatterns in urls.py

Question

I noticed that in Django there are two formats of urlpatterns in file urls.py:

urlpatterns = [
    url(...),
    url(...),
]


        

Answer 1

In Django 1.8+, urlpatterns should simply be a list of url()s. This new syntax actually works in 1.7 as well.

urlpatterns = [
    url(...),
    url(...),
]

The old syntax using pattern is deprecated in Django 1.8, and is removed in Django 1.10.

urlpatterns = pattern('',
    url(...),
    url(...),
)

With the old syntax, you could provide a prefix. The example given in the docs is

urlpatterns = patterns('news.views',
    url(r'^articles/([0-9]{4})/$', 'year_archive'),
    url(r'^articles/([0-9]{4})/([0-9]{2})/$', 'month_archive'),
    url(r'^articles/([0-9]{4})/([0-9]{2})/([0-9]+)/$', 'article_detail'),
)

However, using strings arguments for the view is now deprecated as well, and you should provide the callable instead.

Answer 2

Per the documentation, patterns is:

A function that takes a prefix, and an arbitrary number of URL patterns, and returns a list of URL patterns in the format Django needs.

The first argument to patterns() is a string prefix.

It also provides an example of why you might want to use it:

from django.conf.urls import patterns, url

urlpatterns = patterns('',
    url(r'^articles/([0-9]{4})/$', 'news.views.year_archive'),
    url(r'^articles/([0-9]{4})/([0-9]{2})/$', 'news.views.month_archive'),
    url(r'^articles/([0-9]{4})/([0-9]{2})/([0-9]+)/$', 'news.views.article_detail'),
)

In this example, each view has a common prefix – 'news.views'. Instead of typing that out for each entry in urlpatterns, you can use the first argument to the patterns() function to specify a prefix to apply to each view function.

With this in mind, the above example can be written more concisely as:

from django.conf.urls import patterns, url

urlpatterns = patterns('news.views',
    url(r'^articles/([0-9]{4})/$', 'year_archive'),
    url(r'^articles/([0-9]{4})/([0-9]{2})/$', 'month_archive'),
    url(r'^articles/([0-9]{4})/([0-9]{2})/([0-9]+)/$', 'article_detail'),
)

---

However, note that this function is deprecated:

Deprecated since version 1.8:

urlpatterns should be a plain list of django.conf.urls.url() instances instead.

Note that the explanation as to why includes (with good reason, clearly!):

Thus patterns() serves little purpose and is a burden when teaching new users (answering the newbie’s question "why do I need this empty string as the first argument to patterns()?").