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312 lines
11 KiB
Python
312 lines
11 KiB
Python
"""
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The :mod:`views` module provides the Views you will most probably
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be subclassing in your implementation.
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By setting or modifying class attributes on your view, you change it's predefined behaviour.
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"""
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import re
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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.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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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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return re.sub(camelcase_boundry, ' \\1', content).strip()
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class APIView(View):
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settings = api_settings
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renderer_classes = api_settings.DEFAULT_RENDERERS
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parser_classes = api_settings.DEFAULT_PARSERS
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authentication_classes = api_settings.DEFAULT_AUTHENTICATION
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throttle_classes = api_settings.DEFAULT_THROTTLES
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permission_classes = api_settings.DEFAULT_PERMISSIONS
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content_negotiation_class = api_settings.DEFAULT_CONTENT_NEGOTIATION
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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: 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 = 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 = self.__doc__ or ''
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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 http_method_not_allowed(self, request, *args, **kwargs):
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"""
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Called if `request.method` does not corrospond 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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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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# 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(self) 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 renderers 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 renderers 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(self) 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 thottles that this view uses.
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"""
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return [throttle(self) 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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return conneg.negotiate(request, renderers, self.format_kwarg, force)
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def has_permission(self, request, obj=None):
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"""
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Return `True` if the request should be 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, obj):
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return False
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return True
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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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"""
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for throttle in self.get_throttles():
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if not throttle.allow_request(request):
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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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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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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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if not self.has_permission(request):
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self.permission_denied(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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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.APIException):
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return Response({'detail': exc.detail}, status=exc.status_code)
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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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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
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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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