mirror of
https://github.com/encode/django-rest-framework.git
synced 2024-09-21 11:29:01 +03:00
fc9be55d43
The previous implementation of decorating `APIView.dispach` with the `csrf_exempt` decorator allowed for an easy-to-make mistake where someone could override the `dispatch` method on a view and inadvertantly remove the csrf exemption of their api view. By moving the decoration of the view into the `as_view` logic, it becomes much more difficult to make this mistake.
430 lines
15 KiB
Python
430 lines
15 KiB
Python
"""
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Provides an APIView class that is the base of all views in REST framework.
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"""
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from __future__ import unicode_literals
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from django.core.exceptions import PermissionDenied
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from django.http import Http404
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from django.utils.datastructures import SortedDict
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from django.views.decorators.csrf import csrf_exempt
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from rest_framework import status, exceptions
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from rest_framework.compat import smart_text, HttpResponseBase, View
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from rest_framework.request import Request
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from rest_framework.response import Response
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from rest_framework.settings import api_settings
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from rest_framework.utils import formatting
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def get_view_name(view_cls, suffix=None):
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"""
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Given a view class, return a textual name to represent the view.
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This name is used in the browsable API, and in OPTIONS responses.
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This function is the default for the `VIEW_NAME_FUNCTION` setting.
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"""
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name = view_cls.__name__
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name = formatting.remove_trailing_string(name, 'View')
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name = formatting.remove_trailing_string(name, 'ViewSet')
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name = formatting.camelcase_to_spaces(name)
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if suffix:
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name += ' ' + suffix
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return name
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def get_view_description(view_cls, html=False):
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"""
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Given a view class, return a textual description to represent the view.
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This name is used in the browsable API, and in OPTIONS responses.
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This function is the default for the `VIEW_DESCRIPTION_FUNCTION` setting.
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"""
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description = view_cls.__doc__ or ''
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description = formatting.dedent(smart_text(description))
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if html:
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return formatting.markup_description(description)
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return description
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def exception_handler(exc):
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"""
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Returns the response that should be used for any given exception.
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By default we handle the REST framework `APIException`, and also
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Django's builtin `Http404` and `PermissionDenied` exceptions.
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Any unhandled exceptions may return `None`, which will cause a 500 error
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to be raised.
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"""
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if isinstance(exc, exceptions.APIException):
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headers = {}
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if getattr(exc, 'auth_header', None):
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headers['WWW-Authenticate'] = exc.auth_header
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if getattr(exc, 'wait', None):
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headers['X-Throttle-Wait-Seconds'] = '%d' % exc.wait
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headers['Retry-After'] = '%d' % exc.wait
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return Response({'detail': exc.detail},
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status=exc.status_code,
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headers=headers)
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elif isinstance(exc, Http404):
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return Response({'detail': 'Not found'},
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status=status.HTTP_404_NOT_FOUND)
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elif isinstance(exc, PermissionDenied):
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return Response({'detail': 'Permission denied'},
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status=status.HTTP_403_FORBIDDEN)
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# Note: Unhandled exceptions will raise a 500 error.
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return None
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class APIView(View):
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# The following policies may be set at either globally, or per-view.
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renderer_classes = api_settings.DEFAULT_RENDERER_CLASSES
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parser_classes = api_settings.DEFAULT_PARSER_CLASSES
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authentication_classes = api_settings.DEFAULT_AUTHENTICATION_CLASSES
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throttle_classes = api_settings.DEFAULT_THROTTLE_CLASSES
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permission_classes = api_settings.DEFAULT_PERMISSION_CLASSES
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content_negotiation_class = api_settings.DEFAULT_CONTENT_NEGOTIATION_CLASS
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# Allow dependancy injection of other settings to make testing easier.
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settings = api_settings
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@classmethod
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def as_view(cls, **initkwargs):
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"""
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Store the original class on the view function.
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This allows us to discover information about the view when we do URL
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reverse lookups. Used for breadcrumb generation.
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"""
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view = super(APIView, cls).as_view(**initkwargs)
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view.cls = cls
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# Note: session based authentication is explicitly CSRF validated,
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# all other authentication is CSRF exempt.
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return csrf_exempt(view)
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@property
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def allowed_methods(self):
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"""
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Wrap Django's private `_allowed_methods` interface in a public property.
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"""
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return self._allowed_methods()
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@property
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def default_response_headers(self):
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headers = {
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'Allow': ', '.join(self.allowed_methods),
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}
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if len(self.renderer_classes) > 1:
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headers['Vary'] = 'Accept'
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return headers
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def http_method_not_allowed(self, request, *args, **kwargs):
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"""
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If `request.method` does not correspond to a handler method,
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determine what kind of exception to raise.
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"""
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raise exceptions.MethodNotAllowed(request.method)
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def permission_denied(self, request):
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"""
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If request is not permitted, determine what kind of exception to raise.
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"""
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if not request.successful_authenticator:
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raise exceptions.NotAuthenticated()
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raise exceptions.PermissionDenied()
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def throttled(self, request, wait):
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"""
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If request is throttled, determine what kind of exception to raise.
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"""
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raise exceptions.Throttled(wait)
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def get_authenticate_header(self, request):
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"""
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If a request is unauthenticated, determine the WWW-Authenticate
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header to use for 401 responses, if any.
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"""
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authenticators = self.get_authenticators()
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if authenticators:
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return authenticators[0].authenticate_header(request)
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def get_parser_context(self, http_request):
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"""
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Returns a dict that is passed through to Parser.parse(),
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as the `parser_context` keyword argument.
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"""
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# Note: Additionally `request` and `encoding` will also be added
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# to the context by the Request object.
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return {
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'view': self,
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'args': getattr(self, 'args', ()),
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'kwargs': getattr(self, 'kwargs', {})
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}
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def get_renderer_context(self):
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"""
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Returns a dict that is passed through to Renderer.render(),
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as the `renderer_context` keyword argument.
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"""
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# Note: Additionally 'response' will also be added to the context,
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# by the Response object.
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return {
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'view': self,
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'args': getattr(self, 'args', ()),
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'kwargs': getattr(self, 'kwargs', {}),
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'request': getattr(self, 'request', None)
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}
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def get_view_name(self):
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"""
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Return the view name, as used in OPTIONS responses and in the
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browsable API.
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"""
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func = self.settings.VIEW_NAME_FUNCTION
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return func(self.__class__, getattr(self, 'suffix', None))
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def get_view_description(self, html=False):
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"""
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Return some descriptive text for the view, as used in OPTIONS responses
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and in the browsable API.
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"""
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func = self.settings.VIEW_DESCRIPTION_FUNCTION
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return func(self.__class__, html)
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# API policy instantiation methods
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def get_format_suffix(self, **kwargs):
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"""
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Determine if the request includes a '.json' style format suffix
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"""
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if self.settings.FORMAT_SUFFIX_KWARG:
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return kwargs.get(self.settings.FORMAT_SUFFIX_KWARG)
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def get_renderers(self):
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"""
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Instantiates and returns the list of renderers that this view can use.
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"""
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return [renderer() for renderer in self.renderer_classes]
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def get_parsers(self):
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"""
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Instantiates and returns the list of parsers that this view can use.
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"""
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return [parser() for parser in self.parser_classes]
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def get_authenticators(self):
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"""
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Instantiates and returns the list of authenticators that this view can use.
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"""
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return [auth() for auth in self.authentication_classes]
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def get_permissions(self):
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"""
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Instantiates and returns the list of permissions that this view requires.
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"""
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return [permission() for permission in self.permission_classes]
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def get_throttles(self):
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"""
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Instantiates and returns the list of throttles that this view uses.
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"""
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return [throttle() for throttle in self.throttle_classes]
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def get_content_negotiator(self):
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"""
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Instantiate and return the content negotiation class to use.
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"""
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if not getattr(self, '_negotiator', None):
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self._negotiator = self.content_negotiation_class()
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return self._negotiator
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# API policy implementation methods
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def perform_content_negotiation(self, request, force=False):
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"""
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Determine which renderer and media type to use render the response.
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"""
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renderers = self.get_renderers()
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conneg = self.get_content_negotiator()
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try:
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return conneg.select_renderer(request, renderers, self.format_kwarg)
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except Exception:
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if force:
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return (renderers[0], renderers[0].media_type)
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raise
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def perform_authentication(self, request):
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"""
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Perform authentication on the incoming request.
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Note that if you override this and simply 'pass', then authentication
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will instead be performed lazily, the first time either
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`request.user` or `request.auth` is accessed.
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"""
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request.user
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def check_permissions(self, request):
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"""
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Check if the request should be permitted.
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Raises an appropriate exception if the request is not permitted.
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"""
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for permission in self.get_permissions():
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if not permission.has_permission(request, self):
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self.permission_denied(request)
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def check_object_permissions(self, request, obj):
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"""
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Check if the request should be permitted for a given object.
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Raises an appropriate exception if the request is not permitted.
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"""
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for permission in self.get_permissions():
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if not permission.has_object_permission(request, self, obj):
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self.permission_denied(request)
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def check_throttles(self, request):
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"""
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Check if request should be throttled.
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Raises an appropriate exception if the request is throttled.
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"""
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for throttle in self.get_throttles():
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if not throttle.allow_request(request, self):
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self.throttled(request, throttle.wait())
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# Dispatch methods
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def initialize_request(self, request, *args, **kwargs):
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"""
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Returns the initial request object.
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"""
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parser_context = self.get_parser_context(request)
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return Request(request,
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parsers=self.get_parsers(),
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authenticators=self.get_authenticators(),
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negotiator=self.get_content_negotiator(),
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parser_context=parser_context)
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def initial(self, request, *args, **kwargs):
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"""
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Runs anything that needs to occur prior to calling the method handler.
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"""
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self.format_kwarg = self.get_format_suffix(**kwargs)
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# Ensure that the incoming request is permitted
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self.perform_authentication(request)
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self.check_permissions(request)
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self.check_throttles(request)
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# Perform content negotiation and store the accepted info on the request
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neg = self.perform_content_negotiation(request)
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request.accepted_renderer, request.accepted_media_type = neg
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def finalize_response(self, request, response, *args, **kwargs):
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"""
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Returns the final response object.
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"""
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# Make the error obvious if a proper response is not returned
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assert isinstance(response, HttpResponseBase), (
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'Expected a `Response`, `HttpResponse` or `HttpStreamingResponse` '
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'to be returned from the view, but received a `%s`'
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% type(response)
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)
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if isinstance(response, Response):
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if not getattr(request, 'accepted_renderer', None):
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neg = self.perform_content_negotiation(request, force=True)
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request.accepted_renderer, request.accepted_media_type = neg
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response.accepted_renderer = request.accepted_renderer
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response.accepted_media_type = request.accepted_media_type
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response.renderer_context = self.get_renderer_context()
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for key, value in self.headers.items():
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response[key] = value
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return response
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def handle_exception(self, exc):
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"""
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Handle any exception that occurs, by returning an appropriate response,
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or re-raising the error.
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"""
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if isinstance(exc, (exceptions.NotAuthenticated,
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exceptions.AuthenticationFailed)):
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# WWW-Authenticate header for 401 responses, else coerce to 403
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auth_header = self.get_authenticate_header(self.request)
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if auth_header:
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exc.auth_header = auth_header
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else:
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exc.status_code = status.HTTP_403_FORBIDDEN
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response = self.settings.EXCEPTION_HANDLER(exc)
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if response is None:
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raise
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response.exception = True
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return response
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# Note: Views are made CSRF exempt from within `as_view` as to prevent
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# accidental removal of this exemption in cases where `dispatch` needs to
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# be overridden.
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def dispatch(self, request, *args, **kwargs):
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"""
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`.dispatch()` is pretty much the same as Django's regular dispatch,
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but with extra hooks for startup, finalize, and exception handling.
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"""
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self.args = args
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self.kwargs = kwargs
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request = self.initialize_request(request, *args, **kwargs)
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self.request = request
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self.headers = self.default_response_headers # deprecate?
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try:
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self.initial(request, *args, **kwargs)
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# Get the appropriate handler method
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if request.method.lower() in self.http_method_names:
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handler = getattr(self, request.method.lower(),
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self.http_method_not_allowed)
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else:
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handler = self.http_method_not_allowed
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response = handler(request, *args, **kwargs)
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except Exception as exc:
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response = self.handle_exception(exc)
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self.response = self.finalize_response(request, response, *args, **kwargs)
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return self.response
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def options(self, request, *args, **kwargs):
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"""
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Handler method for HTTP 'OPTIONS' request.
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We may as well implement this as Django will otherwise provide
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a less useful default implementation.
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"""
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return Response(self.metadata(request), status=status.HTTP_200_OK)
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def metadata(self, request):
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"""
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Return a dictionary of metadata about the view.
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Used to return responses for OPTIONS requests.
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"""
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# By default we can't provide any form-like information, however the
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# generic views override this implementation and add additional
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# information for POST and PUT methods, based on the serializer.
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ret = SortedDict()
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ret['name'] = self.get_view_name()
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ret['description'] = self.get_view_description()
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ret['renders'] = [renderer.media_type for renderer in self.renderer_classes]
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ret['parses'] = [parser.media_type for parser in self.parser_classes]
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return ret
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