522 lines
18 KiB
Python
522 lines
18 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 django.conf import settings
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from django.core.exceptions import PermissionDenied
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from django.db import connections, models
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from django.http import Http404
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from django.http.response import HttpResponseBase
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from django.utils.cache import cc_delim_re, patch_vary_headers
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from django.utils.encoding import smart_str
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from django.views.decorators.csrf import csrf_exempt
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from django.views.generic import View
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from rest_framework import exceptions, status
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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.schemas import DefaultSchema
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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):
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"""
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Given a view instance, 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 may be set by some Views, such as a ViewSet.
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name = getattr(view, 'name', None)
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if name is not None:
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return name
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name = view.__class__.__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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# Suffix may be set by some Views, such as a ViewSet.
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suffix = getattr(view, 'suffix', None)
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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, html=False):
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"""
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Given a view instance, 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 may be set by some Views, such as a ViewSet.
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description = getattr(view, 'description', None)
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if description is None:
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description = view.__class__.__doc__ or ''
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description = formatting.dedent(smart_str(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 set_rollback():
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for db in connections.all():
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if db.settings_dict['ATOMIC_REQUESTS'] and db.in_atomic_block:
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db.set_rollback(True)
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def exception_handler(exc, context):
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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 built-in `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, Http404):
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exc = exceptions.NotFound()
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elif isinstance(exc, PermissionDenied):
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exc = exceptions.PermissionDenied()
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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['Retry-After'] = '%d' % exc.wait
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if isinstance(exc.detail, (list, dict)):
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data = exc.detail
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else:
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data = {'detail': exc.detail}
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set_rollback()
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return Response(data, status=exc.status_code, headers=headers)
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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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metadata_class = api_settings.DEFAULT_METADATA_CLASS
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versioning_class = api_settings.DEFAULT_VERSIONING_CLASS
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# Allow dependency injection of other settings to make testing easier.
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settings = api_settings
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schema = DefaultSchema()
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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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if isinstance(getattr(cls, 'queryset', None), models.query.QuerySet):
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def force_evaluation():
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raise RuntimeError(
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'Do not evaluate the `.queryset` attribute directly, '
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'as the result will be cached and reused between requests. '
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'Use `.all()` or call `.get_queryset()` instead.'
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)
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cls.queryset._fetch_all = force_evaluation
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view = super().as_view(**initkwargs)
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view.cls = cls
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view.initkwargs = initkwargs
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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, message=None, code=None):
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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 request.authenticators and not request.successful_authenticator:
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raise exceptions.NotAuthenticated()
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raise exceptions.PermissionDenied(detail=message, code=code)
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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_exception_handler_context(self):
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"""
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Returns a dict that is passed through to EXCEPTION_HANDLER,
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as the `context` argument.
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"""
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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)
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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, 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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def get_exception_handler(self):
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"""
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Returns the exception handler that this view uses.
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"""
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return self.settings.EXCEPTION_HANDLER
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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(
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request,
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message=getattr(permission, 'message', None),
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code=getattr(permission, 'code', None)
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)
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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(
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request,
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message=getattr(permission, 'message', None),
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code=getattr(permission, 'code', None)
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)
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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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throttle_durations = []
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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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throttle_durations.append(throttle.wait())
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if throttle_durations:
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# Filter out `None` values which may happen in case of config / rate
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# changes, see #1438
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durations = [
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duration for duration in throttle_durations
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if duration is not None
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]
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duration = max(durations, default=None)
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self.throttled(request, duration)
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def determine_version(self, request, *args, **kwargs):
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"""
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If versioning is being used, then determine any API version for the
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incoming request. Returns a two-tuple of (version, versioning_scheme)
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"""
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if self.versioning_class is None:
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return (None, None)
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scheme = self.versioning_class()
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return (scheme.determine_version(request, *args, **kwargs), scheme)
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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(
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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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)
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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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# 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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# Determine the API version, if versioning is in use.
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version, scheme = self.determine_version(request, *args, **kwargs)
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request.version, request.versioning_scheme = version, scheme
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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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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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# Add new vary headers to the response instead of overwriting.
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vary_headers = self.headers.pop('Vary', None)
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if vary_headers is not None:
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patch_vary_headers(response, cc_delim_re.split(vary_headers))
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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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exception_handler = self.get_exception_handler()
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context = self.get_exception_handler_context()
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response = exception_handler(exc, context)
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if response is None:
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self.raise_uncaught_exception(exc)
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response.exception = True
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return response
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def raise_uncaught_exception(self, exc):
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if settings.DEBUG:
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request = self.request
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renderer_format = getattr(request.accepted_renderer, 'format')
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use_plaintext_traceback = renderer_format not in ('html', 'api', 'admin')
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request.force_plaintext_errors(use_plaintext_traceback)
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raise exc
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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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"""
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if self.metadata_class is None:
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return self.http_method_not_allowed(request, *args, **kwargs)
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data = self.metadata_class().determine_metadata(request, self)
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return Response(data, status=status.HTTP_200_OK)
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