/
request.py
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/
request.py
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"""
The :mod:`request` module provides a :class:`Request` class used to wrap the standard `request`
object received in all the views.
The wrapped request then offers a richer API, in particular :
- content automatically parsed according to `Content-Type` header,
and available as :meth:`.DATA<Request.DATA>`
- full support of PUT method, including support for file uploads
- form overloading of HTTP method, content type and content
"""
from StringIO import StringIO
from django.http.multipartparser import parse_header
from rest_framework import exceptions
from rest_framework.settings import api_settings
def is_form_media_type(media_type):
"""
Return True if the media type is a valid form media type.
"""
base_media_type, params = parse_header(media_type)
return (base_media_type == 'application/x-www-form-urlencoded' or
base_media_type == 'multipart/form-data')
class Empty(object):
"""
Placeholder for unset attributes.
Cannot use `None`, as that may be a valid value.
"""
pass
def _hasattr(obj, name):
return not getattr(obj, name) is Empty
def clone_request(request, method):
"""
Internal helper method to clone a request, replacing with a different
HTTP method. Used for checking permissions against other methods.
"""
ret = Request(request._request,
request.parsers,
request.authenticators,
request.parser_context)
ret._data = request._data
ret._files = request._files
ret._content_type = request._content_type
ret._stream = request._stream
ret._method = method
if hasattr(request, '_user'):
ret._user = request._user
if hasattr(request, '_auth'):
ret._auth = request._auth
return ret
class Request(object):
"""
Wrapper allowing to enhance a standard `HttpRequest` instance.
Kwargs:
- request(HttpRequest). The original request instance.
- parsers_classes(list/tuple). The parsers to use for parsing the
request content.
- authentication_classes(list/tuple). The authentications used to try
authenticating the request's user.
"""
_METHOD_PARAM = api_settings.FORM_METHOD_OVERRIDE
_CONTENT_PARAM = api_settings.FORM_CONTENT_OVERRIDE
_CONTENTTYPE_PARAM = api_settings.FORM_CONTENTTYPE_OVERRIDE
def __init__(self, request, parsers=None, authenticators=None,
negotiator=None, parser_context=None):
self._request = request
self.parsers = parsers or ()
self.authenticators = authenticators or ()
self.negotiator = negotiator or self._default_negotiator()
self.parser_context = parser_context
self._data = Empty
self._files = Empty
self._method = Empty
self._content_type = Empty
self._stream = Empty
if self.parser_context is None:
self.parser_context = {}
self.parser_context['request'] = self
def _default_negotiator(self):
return api_settings.DEFAULT_CONTENT_NEGOTIATION_CLASS()
@property
def method(self):
"""
Returns the HTTP method.
This allows the `method` to be overridden by using a hidden `form`
field on a form POST request.
"""
if not _hasattr(self, '_method'):
self._load_method_and_content_type()
return self._method
@property
def content_type(self):
"""
Returns the content type header.
This should be used instead of `request.META.get('HTTP_CONTENT_TYPE')`,
as it allows the content type to be overridden by using a hidden form
field on a form POST request.
"""
if not _hasattr(self, '_content_type'):
self._load_method_and_content_type()
return self._content_type
@property
def stream(self):
"""
Returns an object that may be used to stream the request content.
"""
if not _hasattr(self, '_stream'):
self._load_stream()
return self._stream
@property
def QUERY_PARAMS(self):
"""
More semantically correct name for request.GET.
"""
return self._request.GET
@property
def DATA(self):
"""
Parses the request body and returns the data.
Similar to usual behaviour of `request.POST`, except that it handles
arbitrary parsers, and also works on methods other than POST (eg PUT).
"""
if not _hasattr(self, '_data'):
self._load_data_and_files()
return self._data
@property
def FILES(self):
"""
Parses the request body and returns any files uploaded in the request.
Similar to usual behaviour of `request.FILES`, except that it handles
arbitrary parsers, and also works on methods other than POST (eg PUT).
"""
if not _hasattr(self, '_files'):
self._load_data_and_files()
return self._files
@property
def user(self):
"""
Returns the user associated with the current request, as authenticated
by the authentication classes provided to the request.
"""
if not hasattr(self, '_user'):
self._user, self._auth = self._authenticate()
return self._user
@user.setter
def user(self, value):
"""
Sets the user on the current request. This is necessary to maintain
compatilbility with django.contrib.auth where the user proprety is
set in the login and logout functions.
"""
self._user = value
@property
def auth(self):
"""
Returns any non-user authentication information associated with the
request, such as an authentication token.
"""
if not hasattr(self, '_auth'):
self._user, self._auth = self._authenticate()
return self._auth
@auth.setter
def auth(self, value):
"""
Sets any non-user authentication information associated with the
request, such as an authentication token.
"""
self._auth = value
def _load_data_and_files(self):
"""
Parses the request content into self.DATA and self.FILES.
"""
if not _hasattr(self, '_content_type'):
self._load_method_and_content_type()
if not _hasattr(self, '_data'):
self._data, self._files = self._parse()
def _load_method_and_content_type(self):
"""
Sets the method and content_type, and then check if they've
been overridden.
"""
self._content_type = self.META.get('HTTP_CONTENT_TYPE',
self.META.get('CONTENT_TYPE', ''))
self._perform_form_overloading()
# if the HTTP method was not overloaded, we take the raw HTTP method
if not _hasattr(self, '_method'):
self._method = self._request.method
def _load_stream(self):
"""
Return the content body of the request, as a stream.
"""
try:
content_length = int(self.META.get('CONTENT_LENGTH',
self.META.get('HTTP_CONTENT_LENGTH')))
except (ValueError, TypeError):
content_length = 0
if content_length == 0:
self._stream = None
elif hasattr(self._request, 'read'):
self._stream = self._request
else:
self._stream = StringIO(self.raw_post_data)
def _perform_form_overloading(self):
"""
If this is a form POST request, then we need to check if the method and
content/content_type have been overridden by setting them in hidden
form fields or not.
"""
USE_FORM_OVERLOADING = (
self._METHOD_PARAM or
(self._CONTENT_PARAM and self._CONTENTTYPE_PARAM)
)
# We only need to use form overloading on form POST requests.
if (not USE_FORM_OVERLOADING
or self._request.method != 'POST'
or not is_form_media_type(self._content_type)):
return
# At this point we're committed to parsing the request as form data.
self._data = self._request.POST
self._files = self._request.FILES
# Method overloading - change the method and remove the param from the content.
if (self._METHOD_PARAM and
self._METHOD_PARAM in self._data):
self._method = self._data[self._METHOD_PARAM].upper()
# Content overloading - modify the content type, and force re-parse.
if (self._CONTENT_PARAM and
self._CONTENTTYPE_PARAM and
self._CONTENT_PARAM in self._data and
self._CONTENTTYPE_PARAM in self._data):
self._content_type = self._data[self._CONTENTTYPE_PARAM]
self._stream = StringIO(self._data[self._CONTENT_PARAM])
self._data, self._files = (Empty, Empty)
def _parse(self):
"""
Parse the request content, returning a two-tuple of (data, files)
May raise an `UnsupportedMediaType`, or `ParseError` exception.
"""
stream = self.stream
media_type = self.content_type
if stream is None or media_type is None:
return (None, None)
parser = self.negotiator.select_parser(self, self.parsers)
if not parser:
raise exceptions.UnsupportedMediaType(media_type)
parsed = parser.parse(stream, media_type, self.parser_context)
# Parser classes may return the raw data, or a
# DataAndFiles object. Unpack the result as required.
try:
return (parsed.data, parsed.files)
except AttributeError:
return (parsed, None)
def _authenticate(self):
"""
Attempt to authenticate the request using each authentication instance in turn.
Returns a two-tuple of (user, authtoken).
"""
for authenticator in self.authenticators:
user_auth_tuple = authenticator.authenticate(self)
if not user_auth_tuple is None:
return user_auth_tuple
return self._not_authenticated()
def _not_authenticated(self):
"""
Return a two-tuple of (user, authtoken), representing an
unauthenticated request.
By default this will be (AnonymousUser, None).
"""
if api_settings.UNAUTHENTICATED_USER:
user = api_settings.UNAUTHENTICATED_USER()
else:
user = None
if api_settings.UNAUTHENTICATED_TOKEN:
auth = api_settings.UNAUTHENTICATED_TOKEN()
else:
auth = None
return (user, auth)
def __getattr__(self, attr):
"""
Proxy other attributes to the underlying HttpRequest object.
"""
return getattr(self._request, attr)