routers.py

Routers

Resource routing allows you to quickly declare all of the common routes for a given resourceful controller. Instead of declaring separate routes for your index... a resourceful route declares them in a single line of code.

— Ruby on Rails Documentation

Some Web frameworks such as Rails provide functionality for automatically determining how the URLs for an application should be mapped to the logic that deals with handling incoming requests.

REST framework adds support for automatic URL routing to Django, and provides you with a simple, quick and consistent way of wiring your view logic to a set of URLs.

Usage

Here's an example of a simple URL conf, that uses DefaultRouter.

from rest_framework import routers

router = routers.SimpleRouter()
router.register(r'users', UserViewSet)
router.register(r'accounts', AccountViewSet)
urlpatterns = router.urls

There are two mandatory arguments to the register() method:

• prefix - The URL prefix to use for this set of routes.
• viewset - The viewset class.

Optionally, you may also specify an additional argument:

• base_name - The base to use for the URL names that are created. If unset the basename will be automatically generated based on the model or queryset attribute on the viewset, if it has one. Note that if the viewset does not include a model or queryset attribute then you must set base_name when registering the viewset.

The example above would generate the following URL patterns:

• URL pattern: ^users/$ Name: 'user-list'
• URL pattern: ^users/{pk}/$ Name: 'user-detail'
• URL pattern: ^accounts/$ Name: 'account-list'
• URL pattern: ^accounts/{pk}/$ Name: 'account-detail'

Extra link and actions

Any methods on the viewset decorated with @link or @action will also be routed. For example, given a method like this on the UserViewSet class:

from myapp.permissions import IsAdminOrIsSelf
from rest_framework.decorators import action

@action(permission_classes=[IsAdminOrIsSelf])
def set_password(self, request, pk=None):
    ...

The following URL pattern would additionally be generated:

• URL pattern: ^users/{pk}/set_password/$ Name: 'user-set-password'

API Guide

SimpleRouter

This router includes routes for the standard set of list, create, retrieve, update, partial_update and destroy actions. The viewset can also mark additional methods to be routed, using the @link or @action decorators.

By default the URLs created by SimpleRouter are appended with a trailing slash. This behavior can be modified by setting the trailing_slash argument to False when instantiating the router. For example:

router = SimpleRouter(trailing_slash=False)

Trailing slashes are conventional in Django, but are not used by default in some other frameworks such as Rails. Which style you choose to use is largely a matter of preference, although some javascript frameworks may expect a particular routing style.

DefaultRouter

This router is similar to SimpleRouter as above, but additionally includes a default API root view, that returns a response containing hyperlinks to all the list views. It also generates routes for optional .json style format suffixes.

As with SimpleRouter the trailing slashes on the URL routes can be removed by setting the trailing_slash argument to False when instantiating the router.

router = DefaultRouter(trailing_slash=False)

Custom Routers

Implementing a custom router isn't something you'd need to do very often, but it can be useful if you have specific requirements about how the your URLs for your API are structured. Doing so allows you to encapsulate the URL structure in a reusable way that ensures you don't have to write your URL patterns explicitly for each new view.

The simplest way to implement a custom router is to subclass one of the existing router classes. The .routes attribute is used to template the URL patterns that will be mapped to each viewset. The .routes attribute is a list of Route named tuples.

The arguments to the Route named tuple are:

url: A string representing the URL to be routed. May include the following format strings:

• {prefix} - The URL prefix to use for this set of routes.
• {lookup} - The lookup field used to match against a single instance.
• {trailing_slash} - Either a '/' or an empty string, depending on the trailing_slash argument.

mapping: A mapping of HTTP method names to the view methods

name: The name of the URL as used in reverse calls. May include the following format string:

• {basename} - The base to use for the URL names that are created.

initkwargs: A dictionary of any additional arguments that should be passed when instantiating the view. Note that the suffix argument is reserved for identifying the viewset type, used when generating the view name and breadcrumb links.

Example

The following example will only route to the list and retrieve actions, and does not use the trailing slash convention.

from rest_framework.routers import Route, SimpleRouter

class ReadOnlyRouter(SimpleRouter):
    """
    A router for read-only APIs, which doesn't use trailing slashes.
    """
    routes = [
        Route(url=r'^{prefix}$',
              mapping={'get': 'list'},
              name='{basename}-list',
              initkwargs={'suffix': 'List'}),
        Route(url=r'^{prefix}/{lookup}$',
              mapping={'get': 'retrieve'},
              name='{basename}-detail',
              initkwargs={'suffix': 'Detail'})
    ]

The SimpleRouter class provides another example of setting the .routes attribute.

Advanced custom routers

If you want to provide totally custom behavior, you can override BaseRouter and override the get_urls(self) method. The method should inspect the registered viewsets and return a list of URL patterns. The registered prefix, viewset and basename tuples may be inspected by accessing the self.registry attribute.

You may also want to override the get_default_base_name(self, viewset) method, or else always explicitly set the base_name argument when registering your viewsets with the router.