django-rest-framework/djangorestframework/views.py

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"""
The :mod:`views` module provides the Views you will most probably
be subclassing in your implementation.
By setting or modifying class attributes on your view, you change it's predefined behaviour.
"""
import re
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from django.core.exceptions import PermissionDenied
from django.http import Http404
from django.utils.html import escape
from django.utils.safestring import mark_safe
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from django.views.decorators.csrf import csrf_exempt
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from djangorestframework.compat import View as _View, apply_markdown
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from djangorestframework.response import Response
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from djangorestframework.request import Request
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from djangorestframework.settings import api_settings
from djangorestframework import status, exceptions
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def _remove_trailing_string(content, trailing):
"""
Strip trailing component `trailing` from `content` if it exists.
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Used when generating names from view classes.
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"""
if content.endswith(trailing) and content != trailing:
return content[:-len(trailing)]
return content
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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))
return re.sub(re.compile(whitespace_pattern, re.MULTILINE), '', content)
return content
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def _camelcase_to_spaces(content):
"""
Translate 'CamelCaseNames' to 'Camel Case Names'.
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Used when generating names from view classes.
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"""
camelcase_boundry = '(((?<=[a-z])[A-Z])|([A-Z](?![A-Z]|$)))'
return re.sub(camelcase_boundry, ' \\1', content).strip()
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class APIView(_View):
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renderers = api_settings.DEFAULT_RENDERERS
parsers = api_settings.DEFAULT_PARSERS
authentication = api_settings.DEFAULT_AUTHENTICATION
throttle_classes = api_settings.DEFAULT_THROTTLES
permission_classes = api_settings.DEFAULT_PERMISSIONS
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@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
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information about the view when we do URL reverse lookups.
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"""
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view = super(APIView, cls).as_view(**initkwargs)
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view.cls_instance = cls(**initkwargs)
return view
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@property
def allowed_methods(self):
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"""
Return the list of allowed HTTP methods, uppercased.
"""
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return [method.upper() for method in self.http_method_names
if hasattr(self, method)]
@property
def default_response_headers(self):
return {
'Allow': ', '.join(self.allowed_methods),
'Vary': 'Authenticate, Accept'
}
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def get_name(self):
"""
Return the resource or view class name for use as this view's name.
Override to customize.
"""
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name = self.__class__.__name__
name = _remove_trailing_string(name, 'View')
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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.
"""
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description = self.__doc__ or ''
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description = _remove_leading_indent(description)
if html:
return self.markup_description(description)
return description
def markup_description(self, description):
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"""
Apply HTML markup to the description of this view.
"""
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if apply_markdown:
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description = apply_markdown(description)
else:
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description = escape(description).replace('\n', '<br />')
return mark_safe(description)
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def http_method_not_allowed(self, request, *args, **kwargs):
"""
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Called if `request.method` does not corrospond to a handler method.
"""
raise exceptions.MethodNotAllowed(request.method)
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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)
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@property
def _parsed_media_types(self):
"""
Return a list of all the media types that this view can parse.
"""
return [parser.media_type for parser in self.parsers]
@property
def _default_parser(self):
"""
Return the view's default parser class.
"""
return self.parsers[0]
@property
def _rendered_media_types(self):
"""
Return an list of all the media types that this response can render.
"""
return [renderer.media_type for renderer in self.renderers]
@property
def _rendered_formats(self):
"""
Return a list of all the formats that this response can render.
"""
return [renderer.format for renderer in self.renderers]
@property
def _default_renderer(self):
"""
Return the response's default renderer class.
"""
return self.renderers[0]
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def get_permissions(self):
"""
Instantiates and returns the list of permissions that this view requires.
"""
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 requires.
"""
return [throttle(self) for throttle in self.throttle_classes]
def check_permissions(self, request, obj=None):
"""
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Check if request should be permitted.
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"""
for permission in self.get_permissions():
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if not permission.check_permission(request, obj):
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self.permission_denied(request)
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def check_throttles(self, request):
"""
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Check if request should be throttled.
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"""
for throttle in self.get_throttles():
if not throttle.check_throttle(request):
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self.throttled(request, throttle.wait())
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def initialize_request(self, request, *args, **kargs):
"""
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Returns the initial request object.
"""
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return Request(request, parsers=self.parsers, authentication=self.authentication)
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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):
response.view = self
response.request = request
response.renderers = self.renderers
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if api_settings.FORMAT_SUFFIX_KWARG:
response.format = kwargs.get(api_settings.FORMAT_SUFFIX_KWARG, None)
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for key, value in self.headers.items():
response[key] = value
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return response
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def initial(self, request, *args, **kwargs):
"""
Runs anything that needs to occur prior to calling the method handlers.
"""
self.check_permissions(request)
self.check_throttles(request)
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def handle_exception(self, exc):
"""
Handle any exception that occurs, by returning an appropriate response,
or re-raising the error.
"""
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if isinstance(exc, exceptions.Throttled):
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)
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
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# Note: session based authentication is explicitly CSRF validated,
# all other authentication is CSRF exempt.
@csrf_exempt
def dispatch(self, request, *args, **kwargs):
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"""
`APIView.dispatch()` is pretty much the same as Django's regular
`View.dispatch()`, except that it includes hooks to:
* Initialize the request object.
* Finalize the response object.
* Handle exceptions that occur in the handler method.
* An initial hook for code such as permission checking that should
occur prior to running the method handlers.
"""
request = self.initialize_request(request, *args, **kwargs)
self.request = request
self.args = args
self.kwargs = kwargs
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self.headers = self.default_response_headers
try:
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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
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response = handler(request, *args, **kwargs)
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except Exception as exc:
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