Master Django URL Routing: Regex Groups, Reverse Lookup, and Namespaces

1. Introduction

Django matches URLs using the url() function where the first argument is a regular expression. Matching stops at the first successful pattern, and Django automatically redirects to a trailing slash unless APPEND_SLASH = False is set.

url(r'test', views.test)

url(r'test_add', views.test_add)

When a URL is entered without a slash, Django adds it and redirects.

2. Unnamed Groups

Parentheses create an unnamed group; the captured value is passed to the view as a positional argument.

url(r'^test/(\d+)', views.test)

def test(request, xx):
    print(xx)  # xx is the number matched by (\d+)
    return HttpResponse('TEST')

3. Named Groups

Using (?P<name>...) gives the group a name, which is passed to the view as a keyword argument.

url(r'^test_add/(?P<year>\d+)', views.test_add)

def test_add(request, year):
    print(year)
    return HttpResponse('TEST_ADD')

4. Mixing Groups

Unnamed and named groups cannot be mixed in the same pattern, but a single group can be reused multiple times.

url(r'^test/(\d+)/(\d+)/(\d+)', views.test)

url(r'^test_add/(?P<year>\d+)/(?P<year>\d+)/(?P<year>\d+)', views.test_add)

5. Reverse URL Resolution

Assign a name to a URL pattern and use reverse() (backend) or the {% url %} template tag (frontend) to generate the URL programmatically.

url(r'^func/', views.func, name='ooo')

# Backend
reverse('ooo')
# Frontend
<a href="{% url 'ooo' %}">link</a>

6. Reverse with Unnamed and Named Groups

For unnamed groups, pass arguments as a tuple; for named groups, pass a dictionary of keyword arguments.

# Unnamed group reverse
reverse('xxx', args=(123,))
# Named group reverse
reverse('ooo', kwargs={'year': 123})

7. Route Distribution

Each Django app can have its own urls.py. The project’s root urls.py includes app URLs, allowing modular development and reducing redundancy.

# Root URL configuration
urlpatterns = [
    url(r'^admin/', admin.site.urls),
    url(r'^app01/', include('app01.urls')),
    url(r'^app02/', include('app02.urls')),
]
# App‑specific URLs (app01/urls.py)
urlpatterns = [
    url(r'^reg/', views.reg),
]

8. Namespaces (Advanced)

When multiple apps use the same URL name, namespaces prevent collisions. Include the app with a namespace argument and reference URLs as app_name:url_name.

url(r'^app01/', include('app01.urls', namespace='app01'))
url(r'^app02/', include('app02.urls', namespace='app02'))

# In a view
print(reverse('app01:reg'))
print(reverse('app2:reg'))

9. Pseudo‑Static URLs (Overview)

Pseudo‑static URLs disguise dynamic pages as static ones to improve SEO and crawler friendliness.

url(r'^reg.html/', views.reg, name='reg')

10. Further Reading

For more details, see the referenced articles.