3.0 KiB
source: urlpatterns.py
Format suffixes
Section 6.2.1 does not say that content negotiation should be used all the time.
— Roy Fielding, REST discuss mailing list
A common pattern for Web APIs is to use filename extensions on URLs to provide an endpoint for a given media type. For example, 'http://example.com/api/users.json' to serve a JSON representation.
Adding format-suffix patterns to each individual entry in the URLconf for your API is error-prone and non-DRY, so REST framework provides a shortcut to adding these patterns to your URLConf.
format_suffix_patterns
Signature: format_suffix_patterns(urlpatterns, suffix_required=False, allowed=None)
Returns a URL pattern list which includes format suffix patterns appended to each of the URL patterns provided.
Arguments:
- urlpatterns: Required. A URL pattern list.
- suffix_required: Optional. A boolean indicating if suffixes in the URLs should be optional or mandatory. Defaults to
False, meaning that suffixes are optional by default. - allowed: Optional. A list or tuple of valid format suffixes. If not provided, a wildcard format suffix pattern will be used.
Example:
from rest_framework.urlpatterns import format_suffix_patterns
from blog import views
urlpatterns = [
url(r'^/$', views.apt_root),
url(r'^comments/$', views.comment_list),
url(r'^comments/(?P<pk>[0-9]+)/$', views.comment_detail)
]
urlpatterns = format_suffix_patterns(urlpatterns, allowed=['json', 'html'])
When using format_suffix_patterns, you must make sure to add the 'format' keyword argument to the corresponding views. For example:
@api_view(('GET', 'POST'))
def comment_list(request, format=None):
# do stuff...
Or with class based views:
class CommentList(APIView):
def get(self, request, format=None):
# do stuff...
def post(self, request, format=None):
# do stuff...
The name of the kwarg used may be modified by using the FORMAT_SUFFIX_KWARG setting.
Also note that format_suffix_patterns does not support descending into include URL patterns.
Accept headers vs. format suffixes
There seems to be a view among some of the Web community that filename extensions are not a RESTful pattern, and that HTTP Accept headers should always be used instead.
It is actually a misconception. For example, take the following quote from Roy Fielding discussing the relative merits of query parameter media-type indicators vs. file extension media-type indicators:
“That's why I always prefer extensions. Neither choice has anything to do with REST.” — Roy Fielding, REST discuss mailing list
The quote does not mention Accept headers, but it does make it clear that format suffixes should be considered an acceptable pattern.