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"""
Provides an APIView class that is the base of all views in REST framework.
"""
from __future__ import unicode_literals
from django.core.exceptions import PermissionDenied
from django.http import Http404
from django.utils.datastructures import SortedDict
from django.views.decorators.csrf import csrf_exempt
from rest_framework import status, exceptions
from rest_framework.compat import smart_text, HttpResponseBase, View
from rest_framework.request import Request
from rest_framework.response import Response
from rest_framework.settings import api_settings
from rest_framework.utils import formatting
def get_view_name(view_cls, suffix=None):
"""
Given a view class, return a textual name to represent the view.
This name is used in the browsable API, and in OPTIONS responses.
This function is the default for the `VIEW_NAME_FUNCTION` setting.
"""
name = view_cls.__name__
name = formatting.remove_trailing_string(name, 'View')
name = formatting.remove_trailing_string(name, 'ViewSet')
name = formatting.camelcase_to_spaces(name)
if suffix:
name += ' ' + suffix
return name
def get_view_description(view_cls, html=False):
"""
Given a view class, return a textual description to represent the view.
This name is used in the browsable API, and in OPTIONS responses.
This function is the default for the `VIEW_DESCRIPTION_FUNCTION` setting.
"""
description = view_cls.__doc__ or ''
description = formatting.dedent(smart_text(description))
if html:
return formatting.markup_description(description)
return description
def exception_handler(exc):
"""
Returns the response that should be used for any given exception.
By default we handle the REST framework `APIException`, and also
Django's builtin `Http404` and `PermissionDenied` exceptions.
Any unhandled exceptions may return `None`, which will cause a 500 error
to be raised.
"""
if isinstance(exc, exceptions.APIException):
headers = {}
if getattr(exc, 'auth_header', None):
headers['WWW-Authenticate'] = exc.auth_header
if getattr(exc, 'wait', None):
headers['X-Throttle-Wait-Seconds'] = '%d' % exc.wait
return Response({'detail': exc.detail},
status=exc.status_code,
headers=headers)
elif isinstance(exc, Http404):
return Response({'detail': 'Not found'},
status=status.HTTP_404_NOT_FOUND)
elif isinstance(exc, PermissionDenied):
return Response({'detail': 'Permission denied'},
status=status.HTTP_403_FORBIDDEN)
# Note: Unhandled exceptions will raise a 500 error.
return None
class APIView(View):
# The following policies may be set at either globally, or per-view.
renderer_classes = api_settings.DEFAULT_RENDERER_CLASSES
parser_classes = api_settings.DEFAULT_PARSER_CLASSES
authentication_classes = api_settings.DEFAULT_AUTHENTICATION_CLASSES
throttle_classes = api_settings.DEFAULT_THROTTLE_CLASSES
permission_classes = api_settings.DEFAULT_PERMISSION_CLASSES
content_negotiation_class = api_settings.DEFAULT_CONTENT_NEGOTIATION_CLASS
# Allow dependancy injection of other settings to make testing easier.
settings = api_settings
@classmethod
def as_view(cls, **initkwargs):
"""
Store the original class on the view function.
This allows us to discover information about the view when we do URL
reverse lookups. Used for breadcrumb generation.
"""
view = super(APIView, cls).as_view(**initkwargs)
view.cls = cls
return view
@property
def allowed_methods(self):
"""
Wrap Django's private `_allowed_methods` interface in a public property.
"""
return self._allowed_methods()
@property
def default_response_headers(self):
headers = {
'Allow': ', '.join(self.allowed_methods),
}
if len(self.renderer_classes) > 1:
headers['Vary'] = 'Accept'
return headers
def http_method_not_allowed(self, request, *args, **kwargs):
"""
If `request.method` does not correspond to a handler method,
determine what kind of exception to raise.
"""
raise exceptions.MethodNotAllowed(request.method)
def permission_denied(self, request):
"""
If request is not permitted, determine what kind of exception to raise.
"""
if not request.successful_authenticator:
raise exceptions.NotAuthenticated()
raise exceptions.PermissionDenied()
def throttled(self, request, wait):
"""
If request is throttled, determine what kind of exception to raise.
"""
raise exceptions.Throttled(wait)
def get_authenticate_header(self, request):
"""
If a request is unauthenticated, determine the WWW-Authenticate
header to use for 401 responses, if any.
"""
authenticators = self.get_authenticators()
if authenticators:
return authenticators[0].authenticate_header(request)
def get_parser_context(self, http_request):
"""
Returns a dict that is passed through to Parser.parse(),
as the `parser_context` keyword argument.
"""
# Note: Additionally `request` and `encoding` will also be added
# to the context by the Request object.
return {
'view': self,
'args': getattr(self, 'args', ()),
'kwargs': getattr(self, 'kwargs', {})
}
def get_renderer_context(self):
"""
Returns a dict that is passed through to Renderer.render(),
as the `renderer_context` keyword argument.
"""
# Note: Additionally 'response' will also be added to the context,
# by the Response object.
return {
'view': self,
'args': getattr(self, 'args', ()),
'kwargs': getattr(self, 'kwargs', {}),
'request': getattr(self, 'request', None)
}
def get_view_name(self):
"""
Return the view name, as used in OPTIONS responses and in the
browsable API.
"""
func = self.settings.VIEW_NAME_FUNCTION
return func(self.__class__, getattr(self, 'suffix', None))
def get_view_description(self, html=False):
"""
Return some descriptive text for the view, as used in OPTIONS responses
and in the browsable API.
"""
func = self.settings.VIEW_DESCRIPTION_FUNCTION
return func(self.__class__, html)
# API policy instantiation methods
def get_format_suffix(self, **kwargs):
"""
Determine if the request includes a '.json' style format suffix
"""
if self.settings.FORMAT_SUFFIX_KWARG:
return kwargs.get(self.settings.FORMAT_SUFFIX_KWARG)
def get_renderers(self):
"""
Instantiates and returns the list of renderers that this view can use.
"""
return [renderer() for renderer in self.renderer_classes]
def get_parsers(self):
"""
Instantiates and returns the list of parsers that this view can use.
"""
return [parser() for parser in self.parser_classes]
def get_authenticators(self):
"""
Instantiates and returns the list of authenticators that this view can use.
"""
return [auth() for auth in self.authentication_classes]
def get_permissions(self):
"""
Instantiates and returns the list of permissions that this view requires.
"""
return [permission() for permission in self.permission_classes]
def get_throttles(self):
"""
Instantiates and returns the list of throttles that this view uses.
"""
return [throttle() for throttle in self.throttle_classes]
def get_content_negotiator(self):
"""
Instantiate and return the content negotiation class to use.
"""
if not getattr(self, '_negotiator', None):
self._negotiator = self.content_negotiation_class()
return self._negotiator
# API policy implementation methods
def perform_content_negotiation(self, request, force=False):
"""
Determine which renderer and media type to use render the response.
"""
renderers = self.get_renderers()
conneg = self.get_content_negotiator()
try:
return conneg.select_renderer(request, renderers, self.format_kwarg)
except Exception:
if force:
return (renderers[0], renderers[0].media_type)
raise
def perform_authentication(self, request):
"""
Perform authentication on the incoming request.
Note that if you override this and simply 'pass', then authentication
will instead be performed lazily, the first time either
`request.user` or `request.auth` is accessed.
"""
request.user
def check_permissions(self, request):
"""
Check if the request should be permitted.
Raises an appropriate exception if the request is not permitted.
"""
for permission in self.get_permissions():
if not permission.has_permission(request, self):
self.permission_denied(request)
def check_object_permissions(self, request, obj):
"""
Check if the request should be permitted for a given object.
Raises an appropriate exception if the request is not permitted.
"""
for permission in self.get_permissions():
if not permission.has_object_permission(request, self, obj):
self.permission_denied(request)
def check_throttles(self, request):
"""
Check if request should be throttled.
Raises an appropriate exception if the request is throttled.
"""
for throttle in self.get_throttles():
if not throttle.allow_request(request, self):
self.throttled(request, throttle.wait())
# Dispatch methods
def initialize_request(self, request, *args, **kwargs):
"""
Returns the initial request object.
"""
parser_context = self.get_parser_context(request)
return Request(request,
parsers=self.get_parsers(),
authenticators=self.get_authenticators(),
negotiator=self.get_content_negotiator(),
parser_context=parser_context)
def initial(self, request, *args, **kwargs):
"""
Runs anything that needs to occur prior to calling the method handler.
"""
self.format_kwarg = self.get_format_suffix(**kwargs)
# Ensure that the incoming request is permitted
self.perform_authentication(request)
self.check_permissions(request)
self.check_throttles(request)
# Perform content negotiation and store the accepted info on the request
neg = self.perform_content_negotiation(request)
request.accepted_renderer, request.accepted_media_type = neg
def finalize_response(self, request, response, *args, **kwargs):
"""
Returns the final response object.
"""
# Make the error obvious if a proper response is not returned
assert isinstance(response, HttpResponseBase), (
'Expected a `Response`, `HttpResponse` or `HttpStreamingResponse` '
'to be returned from the view, but received a `%s`'
% type(response)
)
if isinstance(response, Response):
if not getattr(request, 'accepted_renderer', None):
neg = self.perform_content_negotiation(request, force=True)
request.accepted_renderer, request.accepted_media_type = neg
response.accepted_renderer = request.accepted_renderer
response.accepted_media_type = request.accepted_media_type
response.renderer_context = self.get_renderer_context()
for key, value in self.headers.items():
response[key] = value
return response
def handle_exception(self, exc):
"""
Handle any exception that occurs, by returning an appropriate response,
or re-raising the error.
"""
if isinstance(exc, (exceptions.NotAuthenticated,
exceptions.AuthenticationFailed)):
# WWW-Authenticate header for 401 responses, else coerce to 403
auth_header = self.get_authenticate_header(self.request)
if auth_header:
exc.auth_header = auth_header
else:
exc.status_code = status.HTTP_403_FORBIDDEN
response = self.settings.EXCEPTION_HANDLER(exc)
if response is None:
raise
response.exception = True
return response
# Note: session based authentication is explicitly CSRF validated,
# all other authentication is CSRF exempt.
@csrf_exempt
def dispatch(self, request, *args, **kwargs):
"""
`.dispatch()` is pretty much the same as Django's regular dispatch,
but with extra hooks for startup, finalize, and exception handling.
"""
self.args = args
self.kwargs = kwargs
request = self.initialize_request(request, *args, **kwargs)
self.request = request
self.headers = self.default_response_headers # deprecate?
try:
self.initial(request, *args, **kwargs)
# Get the appropriate handler method
if request.method.lower() in self.http_method_names:
handler = getattr(self, request.method.lower(),
self.http_method_not_allowed)
else:
handler = self.http_method_not_allowed
response = handler(request, *args, **kwargs)
except Exception as exc:
response = self.handle_exception(exc)
self.response = self.finalize_response(request, response, *args, **kwargs)
return self.response
def options(self, request, *args, **kwargs):
"""
Handler method for HTTP 'OPTIONS' request.
We may as well implement this as Django will otherwise provide
a less useful default implementation.
"""
return Response(self.metadata(request), status=status.HTTP_200_OK)
def metadata(self, request):
"""
Return a dictionary of metadata about the view.
Used to return responses for OPTIONS requests.
"""
# By default we can't provide any form-like information, however the
# generic views override this implementation and add additional
# information for POST and PUT methods, based on the serializer.
ret = SortedDict()
ret['name'] = self.get_view_name()
ret['description'] = self.get_view_description()
ret['renders'] = [renderer.media_type for renderer in self.renderer_classes]
ret['parses'] = [parser.media_type for parser in self.parser_classes]
return ret
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