A real example of URL Namespace
Typically, they are used to put each application's URLs into their own namespace. This prevents the reverse()
Django function and the {% url %}
template function from returning the wrong URL because the URL-pattern name happened to match in another app.
What I have in my project-level urls.py
file is the following:
from django.conf.urls.defaults import *
from django.conf import settings
from django.contrib import admin
admin.autodiscover()
urlpatterns = patterns('',
url(r'^$', 'main.views.main', name='main'),
url(r'^login$', 'django.contrib.auth.views.login', name="login"),
url(r'^logout$', 'django.contrib.auth.views.logout',
{"next_page": "/"}, name="logout"),
# Admin
url(r'^admin/doc/', include('django.contrib.admindocs.urls')),
url(r'^admin/', include(admin.site.urls)),
)
# Auto-add the applications.
for app in settings.LOCAL_APPS:
urlpatterns += patterns('',
url(r'^{0}/'.format(app), include(app + '.urls', namespace=app)),
)
Note the last section: this goes through the applications I have installed (settings.LOCAL_APPS
is a setting I added that contains only my apps; it gets added to INSTALLED_APPS
which has other things like South), looks for a urls.py
in each of them, and imports those URLs into a namespace named after the app, and also puts those URLs into a URL subdirectory named after the app.
So, for example, if I have an app named hosts
, and hosts/urls.py
looks like:
from django.conf.urls.defaults import *
urlpatterns = patterns('hosts.views',
url(r'^$', 'show_hosts', name='list'),
)
Now my views.py
can call reverse("hosts:list")
to get the URL to the page that calls hosts.views.show_hosts
, and it will look something like "/hosts/"
. Same goes for {% url "hosts:list" %}
in a template. This way I don't have to worry about colliding with a URL named "list" in another app, and I don't have to prefix every name with hosts_
.
Note that the login page is at {% url "login" %}
since it wasn't given a namespace.
Consider you are using a url pattern as belowurl(r'^login/',include('app_name', name='login'))
Also Consider you are using a third-party app like Django-RestFramework.
When you use the app, you have to declare the following line in URLs conf file of the project.
url(r'^api-auth/', include('rest_framework.urls', namespace='rest_framework'))
Now if you check the code of rest-framework, you will find the below code in urls.py file
urlpatterns = [
url(r'^login/$', login, login_kwargs, name='login'),
url(r'^logout/$', logout, name='logout'),
]
We have used 'login' name for a URL pattern in our project and the same name is being used by Django-rest-framework for one of their URL patterns. When you use reverse('login'), Django will get confused.
To resolve these kinds of issues, we use namespace.
@register.simple_tag
def optional_docs_login(request):
"""
Include a login snippet if REST framework's login view is in the URLconf.
"""
try:
login_url = reverse('rest_framework:login')
except NoReverseMatch:
return 'log in'
URL names of a namespace will never collide with other namespaces.
A namespaced URL pattern can be reversed using reverse('namespace:url_name')