- 1.5
- Documentation version: development
django.core.urlresolvers utility functions¶
reverse()¶
If you need to use something similar to the url template tag in your code, Django provides the following function:
- reverse(viewname[, urlconf=None, args=None, kwargs=None, current_app=None])¶
viewname is either the function name (either a function reference, or the string version of the name, if you used that form in urlpatterns) or the URL pattern name. Normally, you won’t need to worry about the urlconf parameter and will only pass in the positional and keyword arguments to use in the URL matching. For example:
from django.core.urlresolvers import reverse def myview(request): return HttpResponseRedirect(reverse('arch-summary', args=[1945]))
The reverse() function can reverse a large variety of regular expression patterns for URLs, but not every possible one. The main restriction at the moment is that the pattern cannot contain alternative choices using the vertical bar ("|") character. You can quite happily use such patterns for matching against incoming URLs and sending them off to views, but you cannot reverse such patterns.
The current_app argument allows you to provide a hint to the resolver indicating the application to which the currently executing view belongs. This current_app argument is used as a hint to resolve application namespaces into URLs on specific application instances, according to the namespaced URL resolution strategy.
You can use kwargs instead of args. For example:
>>> reverse('admin:app_list', kwargs={'app_label': 'auth'}) '/admin/auth/'
args and kwargs cannot be passed to reverse() at the same time.
Make sure your views are all correct.
As part of working out which URL names map to which patterns, the reverse() function has to import all of your URLconf files and examine the name of each view. This involves importing each view function. If there are any errors whilst importing any of your view functions, it will cause reverse() to raise an error, even if that view function is not the one you are trying to reverse.
Make sure that any views you reference in your URLconf files exist and can be imported correctly. Do not include lines that reference views you haven’t written yet, because those views will not be importable.
Note
The string returned by reverse() is already urlquoted. For example:
>>> reverse('cities', args=[u'Orléans']) '.../Orl%C3%A9ans/'
Applying further encoding (such as urlquote() or urllib.quote) to the output of reverse() may produce undesirable results.
reverse_lazy()¶
A lazily evaluated version of reverse().
- reverse_lazy(viewname[, urlconf=None, args=None, kwargs=None, current_app=None])¶
It is useful for when you need to use a URL reversal before your project’s URLConf is loaded. Some common cases where this function is necessary are:
- providing a reversed URL as the url attribute of a generic class-based view.
- providing a reversed URL to a decorator (such as the login_url argument for the django.contrib.auth.decorators.permission_required() decorator).
- providing a reversed URL as a default value for a parameter in a function’s signature.
resolve()¶
The resolve() function can be used for resolving URL paths to the corresponding view functions. It has the following signature:
- resolve(path, urlconf=None)¶
path is the URL path you want to resolve. As with reverse(), you don’t need to worry about the urlconf parameter. The function returns a ResolverMatch object that allows you to access various meta-data about the resolved URL.
If the URL does not resolve, the function raises an Http404 exception.
- class ResolverMatch¶
- func¶
The view function that would be used to serve the URL
- args¶
The arguments that would be passed to the view function, as parsed from the URL.
- kwargs¶
The keyword arguments that would be passed to the view function, as parsed from the URL.
- url_name¶
The name of the URL pattern that matches the URL.
- app_name¶
The application namespace for the URL pattern that matches the URL.
- namespace¶
The instance namespace for the URL pattern that matches the URL.
- namespaces¶
The list of individual namespace components in the full instance namespace for the URL pattern that matches the URL. i.e., if the namespace is foo:bar, then namespaces will be ['foo', 'bar'].
A ResolverMatch object can then be interrogated to provide information about the URL pattern that matches a URL:
# Resolve a URL match = resolve('/some/path/') # Print the URL pattern that matches the URL print(match.url_name)
A ResolverMatch object can also be assigned to a triple:
func, args, kwargs = resolve('/some/path/')
One possible use of resolve() would be to test whether a view would raise a Http404 error before redirecting to it:
from urlparse import urlparse from django.core.urlresolvers import resolve from django.http import HttpResponseRedirect, Http404 def myview(request): next = request.META.get('HTTP_REFERER', None) or '/' response = HttpResponseRedirect(next) # modify the request and response as required, e.g. change locale # and set corresponding locale cookie view, args, kwargs = resolve(urlparse(next)[2]) kwargs['request'] = request try: view(*args, **kwargs) except Http404: return HttpResponseRedirect('/') return response
get_script_prefix()¶
- get_script_prefix()¶
Normally, you should always use reverse() to define URLs within your application. However, if your application constructs part of the URL hierarchy itself, you may occasionally need to generate URLs. In that case, you need to be able to find the base URL of the Django project within its Web server (normally, reverse() takes care of this for you). In that case, you can call get_script_prefix(), which will return the script prefix portion of the URL for your Django project. If your Django project is at the root of its web server, this is always "/".
Questions/Feedback
Having trouble? We'd like to help!
- Try the FAQ — it's got answers to many common questions.
- Search for information in the archives of the django-users mailing list, or post a question.
- Ask a question in the #django IRC channel, or search the IRC logs to see if it has been asked before.
- If you notice errors with this documentation, please open a ticket and let us know! Please only use the ticket tracker for criticisms and improvements on the docs. For tech support, use the resources above.