django-rest-framework/rest_framework/views.py
2012-10-30 00:30:52 +01:00

371 lines
13 KiB
Python

"""
Provides an APIView class that is used as the base of all class-based views.
"""
import re
from django.core.exceptions import PermissionDenied
from django.http import Http404
from django.utils.html import escape
from django.utils.safestring import mark_safe
from django.views.decorators.csrf import csrf_exempt
from rest_framework import status, exceptions
from rest_framework.compat import View, apply_markdown
from rest_framework.response import Response
from rest_framework.request import Request
from rest_framework.settings import api_settings
def _remove_trailing_string(content, trailing):
"""
Strip trailing component `trailing` from `content` if it exists.
Used when generating names from view classes.
"""
if content.endswith(trailing) and content != trailing:
return content[:-len(trailing)]
return content
def _remove_leading_indent(content):
"""
Remove leading indent from a block of text.
Used when generating descriptions from docstrings.
"""
whitespace_counts = [len(line) - len(line.lstrip(' '))
for line in content.splitlines()[1:] if line.lstrip()]
# unindent the content if needed
if whitespace_counts:
whitespace_pattern = '^' + (' ' * min(whitespace_counts))
content = re.sub(re.compile(whitespace_pattern, re.MULTILINE), '', content)
content = content.strip('\n')
return content
def _camelcase_to_spaces(content):
"""
Translate 'CamelCaseNames' to 'Camel Case Names'.
Used when generating names from view classes.
"""
camelcase_boundry = '(((?<=[a-z])[A-Z])|([A-Z](?![A-Z]|$)))'
content = re.sub(camelcase_boundry, ' \\1', content).strip()
return ' '.join(content.split('_')).title()
class APIView(View):
settings = api_settings
renderer_classes = api_settings.DEFAULT_RENDERER_CLASSES
parser_classes = api_settings.DEFAULT_PARSER_CLASSES
authentication_classes = api_settings.DEFAULT_AUTHENTICATION_CLASSES
throttle_classes = api_settings.DEFAULT_THROTTLE_CLASSES
permission_classes = api_settings.DEFAULT_PERMISSION_CLASSES
content_negotiation_class = api_settings.DEFAULT_CONTENT_NEGOTIATION_CLASS
@classmethod
def as_view(cls, **initkwargs):
"""
Override the default :meth:`as_view` to store an instance of the view
as an attribute on the callable function. This allows us to discover
information about the view when we do URL reverse lookups.
"""
# TODO: deprecate?
view = super(APIView, cls).as_view(**initkwargs)
view.cls_instance = cls(**initkwargs)
return view
@property
def allowed_methods(self):
"""
Return the list of allowed HTTP methods, uppercased.
"""
return [method.upper() for method in self.http_method_names
if hasattr(self, method)]
@property
def default_response_headers(self):
# TODO: deprecate?
# TODO: Only vary by accept if multiple renderers
return {
'Allow': ', '.join(self.allowed_methods),
'Vary': 'Accept'
}
def get_name(self):
"""
Return the resource or view class name for use as this view's name.
Override to customize.
"""
# TODO: deprecate?
name = self.__class__.__name__
name = _remove_trailing_string(name, 'View')
return _camelcase_to_spaces(name)
def get_description(self, html=False):
"""
Return the resource or view docstring for use as this view's description.
Override to customize.
"""
# TODO: deprecate?
description = self.__doc__ or ''
description = _remove_leading_indent(description)
if html:
return self.markup_description(description)
return description
def markup_description(self, description):
"""
Apply HTML markup to the description of this view.
"""
# TODO: deprecate?
if apply_markdown:
description = apply_markdown(description)
else:
description = escape(description).replace('\n', '<br />')
return mark_safe(description)
def metadata(self, request):
return {
'name': self.get_name(),
'description': self.get_description(),
'renders': [renderer.media_type for renderer in self.renderer_classes],
'parses': [parser.media_type for parser in self.parser_classes],
}
# TODO: Add 'fields', from serializer info, if it exists.
# serializer = self.get_serializer()
# if serializer is not None:
# field_name_types = {}
# for name, field in form.fields.iteritems():
# field_name_types[name] = field.__class__.__name__
# content['fields'] = field_name_types
def http_method_not_allowed(self, request, *args, **kwargs):
"""
Called if `request.method` does not corrospond to a handler method.
"""
raise exceptions.MethodNotAllowed(request.method)
def permission_denied(self, request):
"""
If request is not permitted, determine what kind of exception to raise.
"""
raise exceptions.PermissionDenied()
def throttled(self, request, wait):
"""
If request is throttled, determine what kind of exception to raise.
"""
raise exceptions.Throttled(wait)
def get_parser_context(self, http_request):
"""
Returns a dict that is passed through to Parser.parse(),
as the `parser_context` keyword argument.
"""
# Note: Additionally `request` will also be added to the context
# by the Request object.
return {
'view': self,
'args': getattr(self, 'args', ()),
'kwargs': getattr(self, 'kwargs', {})
}
def get_renderer_context(self):
"""
Returns a dict that is passed through to Renderer.render(),
as the `renderer_context` keyword argument.
"""
# Note: Additionally 'response' will also be added to the context,
# by the Response object.
return {
'view': self,
'args': getattr(self, 'args', ()),
'kwargs': getattr(self, 'kwargs', {}),
'request': getattr(self, 'request', None)
}
# API policy instantiation methods
def get_format_suffix(self, **kwargs):
"""
Determine if the request includes a '.json' style format suffix
"""
if self.settings.FORMAT_SUFFIX_KWARG:
return kwargs.get(self.settings.FORMAT_SUFFIX_KWARG)
def get_renderers(self):
"""
Instantiates and returns the list of renderers that this view can use.
"""
return [renderer() for renderer in self.renderer_classes]
def get_parsers(self):
"""
Instantiates and returns the list of renderers that this view can use.
"""
return [parser() for parser in self.parser_classes]
def get_authenticators(self):
"""
Instantiates and returns the list of renderers that this view can use.
"""
return [auth() for auth in self.authentication_classes]
def get_permissions(self):
"""
Instantiates and returns the list of permissions that this view requires.
"""
return [permission() for permission in self.permission_classes]
def get_throttles(self):
"""
Instantiates and returns the list of throttles that this view uses.
"""
return [throttle() for throttle in self.throttle_classes]
def get_content_negotiator(self):
"""
Instantiate and return the content negotiation class to use.
"""
if not getattr(self, '_negotiator', None):
self._negotiator = self.content_negotiation_class()
return self._negotiator
# API policy implementation methods
def perform_content_negotiation(self, request, force=False):
"""
Determine which renderer and media type to use render the response.
"""
renderers = self.get_renderers()
conneg = self.get_content_negotiator()
try:
return conneg.select_renderer(request, renderers, self.format_kwarg)
except:
if force:
return (renderers[0], renderers[0].media_type)
raise
def has_permission(self, request, obj=None):
"""
Return `True` if the request should be permitted.
"""
for permission in self.get_permissions():
if not permission.has_permission(request, self, obj):
return False
return True
def check_throttles(self, request):
"""
Check if request should be throttled.
"""
for throttle in self.get_throttles():
if not throttle.allow_request(request, self):
self.throttled(request, throttle.wait())
# Dispatch methods
def initialize_request(self, request, *args, **kargs):
"""
Returns the initial request object.
"""
parser_context = self.get_parser_context(request)
return Request(request,
parsers=self.get_parsers(),
authenticators=self.get_authenticators(),
negotiator=self.get_content_negotiator(),
parser_context=parser_context)
def initial(self, request, *args, **kwargs):
"""
Runs anything that needs to occur prior to calling the method handler.
"""
self.format_kwarg = self.get_format_suffix(**kwargs)
# Ensure that the incoming request is permitted
if not self.has_permission(request):
self.permission_denied(request)
self.check_throttles(request)
# Perform content negotiation and store the accepted info on the request
neg = self.perform_content_negotiation(request)
request.accepted_renderer, request.accepted_media_type = neg
def finalize_response(self, request, response, *args, **kwargs):
"""
Returns the final response object.
"""
if isinstance(response, Response):
if not getattr(request, 'accepted_renderer', None):
neg = self.perform_content_negotiation(request, force=True)
request.accepted_renderer, request.accepted_media_type = neg
response.accepted_renderer = request.accepted_renderer
response.accepted_media_type = request.accepted_media_type
response.renderer_context = self.get_renderer_context()
for key, value in self.headers.items():
response[key] = value
return response
def handle_exception(self, exc):
"""
Handle any exception that occurs, by returning an appropriate response,
or re-raising the error.
"""
if isinstance(exc, exceptions.Throttled):
# Throttle wait header
self.headers['X-Throttle-Wait-Seconds'] = '%d' % exc.wait
if isinstance(exc, exceptions.APIException):
return Response({'detail': exc.detail}, status=exc.status_code)
elif isinstance(exc, Http404):
return Response({'detail': 'Not found'},
status=status.HTTP_404_NOT_FOUND)
elif isinstance(exc, PermissionDenied):
return Response({'detail': 'Permission denied'},
status=status.HTTP_403_FORBIDDEN)
raise
# Note: session based authentication is explicitly CSRF validated,
# all other authentication is CSRF exempt.
@csrf_exempt
def dispatch(self, request, *args, **kwargs):
"""
`.dispatch()` is pretty much the same as Django's regular dispatch,
but with extra hooks for startup, finalize, and exception handling.
"""
request = self.initialize_request(request, *args, **kwargs)
self.request = request
self.args = args
self.kwargs = kwargs
self.headers = self.default_response_headers # deprecate?
try:
self.initial(request, *args, **kwargs)
# Get the appropriate handler method
if request.method.lower() in self.http_method_names:
handler = getattr(self, request.method.lower(),
self.http_method_not_allowed)
else:
handler = self.http_method_not_allowed
response = handler(request, *args, **kwargs)
except Exception as exc:
response = self.handle_exception(exc)
self.response = self.finalize_response(request, response, *args, **kwargs)
return self.response
def options(self, request, *args, **kwargs):
"""
Handler method for HTTP 'OPTIONS' request.
We may as well implement this as Django will otherwise provide
a less useful default implementation.
"""
return Response(self.metadata(request), status=status.HTTP_200_OK)