django-rest-framework/djangorestframework/request.py

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"""
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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.
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The wrapped request then offers a richer API, in particular :
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- content automatically parsed according to `Content-Type` header,
and available as :meth:`.DATA<Request.DATA>`
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- full support of PUT method, including support for file uploads
- form overloading of HTTP method, content type and content
"""
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from djangorestframework import status
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from djangorestframework.utils.mediatypes import is_form_media_type
from StringIO import StringIO
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__all__ = ('Request',)
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class Empty:
pass
def _hasattr(obj, name):
return not getattr(obj, name) is Empty
class Request(object):
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"""
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Wrapper allowing to enhance a standard `HttpRequest` instance.
Kwargs:
- request(HttpRequest). The original request instance.
- parsers(list/tuple). The parsers to use for parsing the request content.
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"""
_USE_FORM_OVERLOADING = True
_METHOD_PARAM = '_method'
_CONTENTTYPE_PARAM = '_content_type'
_CONTENT_PARAM = '_content'
def __init__(self, request=None, parsers=None):
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self._request = request
self.parsers = parsers or ()
self._data = Empty
self._files = Empty
self._method = Empty
self._content_type = Empty
self._stream = Empty
def get_parsers(self):
"""
Instantiates and returns the list of parsers the request will use.
"""
return [parser() for parser in self.parsers]
@property
def method(self):
"""
Returns the HTTP method.
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This allows the `method` to be overridden by using a hidden `form`
field on a form POST request.
"""
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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.
"""
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if not _hasattr(self, '_content_type'):
self._load_method_and_content_type()
return self._content_type
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@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 DATA(self):
"""
Parses the request body and returns the data.
Similar to ``request.POST``, except that it handles arbitrary parsers,
and also works on methods other than POST (eg PUT).
"""
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if not _hasattr(self, '_data'):
self._load_data_and_files()
return self._data
@property
def FILES(self):
"""
Parses the request body and returns the files.
Similar to ``request.FILES``, except that it handles arbitrary parsers,
and also works on methods other than POST (eg PUT).
"""
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if not _hasattr(self, '_files'):
self._load_data_and_files()
return self._files
def _load_data_and_files(self):
"""
Parses the request content into self.DATA and self.FILES.
"""
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if not _hasattr(self, '_content_type'):
self._load_method_and_content_type()
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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()
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# if the HTTP method was not overloaded, we take the raw HTTP method
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if not _hasattr(self, '_method'):
self._method = self._request.method
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def _load_stream(self):
try:
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content_length = int(self.META.get('CONTENT_LENGTH',
self.META.get('HTTP_CONTENT_LENGTH')))
except (ValueError, TypeError):
content_length = 0
if content_length == 0:
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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):
"""
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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.
"""
# We only need to use form overloading on form POST requests.
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if (not self._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.
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self._data = self._request.POST
self._files = self._request.FILES
# Method overloading - change the method and remove the param from the content.
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if self._METHOD_PARAM in self._data:
# NOTE: `pop` on a `QueryDict` returns a list of values.
self._method = self._data.pop(self._METHOD_PARAM)[0].upper()
# Content overloading - modify the content type, and re-parse.
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if (self._CONTENT_PARAM in self._data and
self._CONTENTTYPE_PARAM in self._data):
self._content_type = self._data.pop(self._CONTENTTYPE_PARAM)[0]
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self._stream = StringIO(self._data.pop(self._CONTENT_PARAM)[0])
(self._data, self._files) = self._parse()
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def _parse(self):
"""
Parse the request content.
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May raise a 415 ImmediateResponse (Unsupported Media Type), or a
400 ImmediateResponse (Bad Request).
"""
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if self.stream is None or self.content_type is None:
return (None, None)
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for parser in self.get_parsers():
if parser.can_handle_request(self.content_type):
return parser.parse(self.stream, self.META, self.upload_handlers)
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self._raise_415_response(self._content_type)
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def _raise_415_response(self, content_type):
"""
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Raise a 415 response if we cannot parse the given content type.
"""
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from djangorestframework.response import ImmediateResponse
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raise ImmediateResponse(
{
'error': 'Unsupported media type in request \'%s\'.'
% content_type
},
status=status.HTTP_415_UNSUPPORTED_MEDIA_TYPE)
def __getattr__(self, name):
"""
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Proxy other attributes to the underlying HttpRequest object.
"""
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return getattr(self._request, name)