mirror of
https://github.com/encode/django-rest-framework.git
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406 lines
14 KiB
Python
406 lines
14 KiB
Python
"""
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Provides an APIView class that is used as the base of all class-based views.
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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.encoding import force_unicode
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from django.utils.html import escape
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from django.utils.safestring import mark_safe
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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 View, apply_markdown
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from rest_framework.response import Response
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from rest_framework.request import Request
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from rest_framework.settings import api_settings
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import re
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def _remove_trailing_string(content, trailing):
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"""
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Strip trailing component `trailing` from `content` if it exists.
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Used when generating names from view classes.
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"""
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if content.endswith(trailing) and content != trailing:
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return content[:-len(trailing)]
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return content
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def _remove_leading_indent(content):
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"""
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Remove leading indent from a block of text.
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Used when generating descriptions from docstrings.
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"""
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whitespace_counts = [len(line) - len(line.lstrip(' '))
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for line in content.splitlines()[1:] if line.lstrip()]
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# unindent the content if needed
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if whitespace_counts:
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whitespace_pattern = '^' + (' ' * min(whitespace_counts))
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content = re.sub(re.compile(whitespace_pattern, re.MULTILINE), '', content)
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content = content.strip('\n')
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return content
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def _camelcase_to_spaces(content):
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"""
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Translate 'CamelCaseNames' to 'Camel Case Names'.
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Used when generating names from view classes.
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"""
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camelcase_boundry = '(((?<=[a-z])[A-Z])|([A-Z](?![A-Z]|$)))'
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content = re.sub(camelcase_boundry, ' \\1', content).strip()
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return ' '.join(content.split('_')).title()
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class APIView(View):
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settings = api_settings
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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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@classmethod
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def as_view(cls, **initkwargs):
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"""
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Override the default :meth:`as_view` to store an instance of the view
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as an attribute on the callable function. This allows us to discover
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information about the view when we do URL reverse lookups.
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"""
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# TODO: deprecate?
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view = super(APIView, cls).as_view(**initkwargs)
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view.cls_instance = cls(**initkwargs)
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return view
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@property
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def allowed_methods(self):
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"""
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Return the list of allowed HTTP methods, uppercased.
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"""
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return [method.upper() for method in self.http_method_names
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if hasattr(self, method)]
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@property
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def default_response_headers(self):
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# TODO: deprecate?
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# TODO: Only vary by accept if multiple renderers
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return {
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'Allow': ', '.join(self.allowed_methods),
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'Vary': 'Accept'
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}
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def get_name(self):
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"""
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Return the resource or view class name for use as this view's name.
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Override to customize.
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"""
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# TODO: deprecate?
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name = force_unicode(self.__class__.__name__)
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name = _remove_trailing_string(name, 'View')
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return _camelcase_to_spaces(name)
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def get_description(self, html=False):
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"""
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Return the resource or view docstring for use as this view's description.
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Override to customize.
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"""
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# TODO: deprecate?
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description = force_unicode(self.__doc__) or u''
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description = _remove_leading_indent(description)
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if html:
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return self.markup_description(description)
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return description
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def markup_description(self, description):
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"""
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Apply HTML markup to the description of this view.
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"""
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# TODO: deprecate?
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if apply_markdown:
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description = apply_markdown(description)
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else:
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description = escape(description).replace('\n', '<br />')
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return mark_safe(description)
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def metadata(self, request):
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return {
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'name': self.get_name(),
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'description': self.get_description(),
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'renders': [renderer.media_type for renderer in self.renderer_classes],
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'parses': [parser.media_type for parser in self.parser_classes],
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}
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# TODO: Add 'fields', from serializer info, if it exists.
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# serializer = self.get_serializer()
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# if serializer is not None:
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# field_name_types = {}
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# for name, field in form.fields.iteritems():
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# field_name_types[name] = field.__class__.__name__
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# content['fields'] = field_name_types
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def http_method_not_allowed(self, request, *args, **kwargs):
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"""
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Called if `request.method` does not correspond to a handler method.
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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 self.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` will also be added to the context
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# 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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# 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 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, **kargs):
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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.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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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.Throttled):
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# Throttle wait header
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self.headers['X-Throttle-Wait-Seconds'] = '%d' % exc.wait
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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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self.headers['WWW-Authenticate'] = auth_header
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else:
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exc.status_code = status.HTTP_403_FORBIDDEN
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if isinstance(exc, exceptions.APIException):
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return Response({'detail': exc.detail},
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status=exc.status_code,
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exception=True)
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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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exception=True)
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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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exception=True)
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raise
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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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@csrf_exempt
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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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request = self.initialize_request(request, *args, **kwargs)
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self.request = request
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self.args = args
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self.kwargs = kwargs
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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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