django-rest-framework/rest_framework/negotiation.py
Carlton Gibson 0407a0df8a
Dropped Python 2 compatibility. (#6615)
Thanks to Jon Dufresne (@jdufresne) for review.

Co-authored-by: Asif Saif Uddin <auvipy@gmail.com>
Co-authored-by: Rizwan Mansuri <Rizwan@webbyfox.com>
2019-04-30 17:53:44 +02:00

96 lines
3.9 KiB
Python

"""
Content negotiation deals with selecting an appropriate renderer given the
incoming request. Typically this will be based on the request's Accept header.
"""
from django.http import Http404
from rest_framework import HTTP_HEADER_ENCODING, exceptions
from rest_framework.settings import api_settings
from rest_framework.utils.mediatypes import (
_MediaType, media_type_matches, order_by_precedence
)
class BaseContentNegotiation:
def select_parser(self, request, parsers):
raise NotImplementedError('.select_parser() must be implemented')
def select_renderer(self, request, renderers, format_suffix=None):
raise NotImplementedError('.select_renderer() must be implemented')
class DefaultContentNegotiation(BaseContentNegotiation):
settings = api_settings
def select_parser(self, request, parsers):
"""
Given a list of parsers and a media type, return the appropriate
parser to handle the incoming request.
"""
for parser in parsers:
if media_type_matches(parser.media_type, request.content_type):
return parser
return None
def select_renderer(self, request, renderers, format_suffix=None):
"""
Given a request and a list of renderers, return a two-tuple of:
(renderer, media type).
"""
# Allow URL style format override. eg. "?format=json
format_query_param = self.settings.URL_FORMAT_OVERRIDE
format = format_suffix or request.query_params.get(format_query_param)
if format:
renderers = self.filter_renderers(renderers, format)
accepts = self.get_accept_list(request)
# Check the acceptable media types against each renderer,
# attempting more specific media types first
# NB. The inner loop here isn't as bad as it first looks :)
# Worst case is we're looping over len(accept_list) * len(self.renderers)
for media_type_set in order_by_precedence(accepts):
for renderer in renderers:
for media_type in media_type_set:
if media_type_matches(renderer.media_type, media_type):
# Return the most specific media type as accepted.
media_type_wrapper = _MediaType(media_type)
if (
_MediaType(renderer.media_type).precedence >
media_type_wrapper.precedence
):
# Eg client requests '*/*'
# Accepted media type is 'application/json'
full_media_type = ';'.join(
(renderer.media_type,) +
tuple('{}={}'.format(
key, value.decode(HTTP_HEADER_ENCODING))
for key, value in media_type_wrapper.params.items()))
return renderer, full_media_type
else:
# Eg client requests 'application/json; indent=8'
# Accepted media type is 'application/json; indent=8'
return renderer, media_type
raise exceptions.NotAcceptable(available_renderers=renderers)
def filter_renderers(self, renderers, format):
"""
If there is a '.json' style format suffix, filter the renderers
so that we only negotiation against those that accept that format.
"""
renderers = [renderer for renderer in renderers
if renderer.format == format]
if not renderers:
raise Http404
return renderers
def get_accept_list(self, request):
"""
Given the incoming request, return a tokenized list of media
type strings.
"""
header = request.META.get('HTTP_ACCEPT', '*/*')
return [token.strip() for token in header.split(',')]