mirror of
https://github.com/encode/django-rest-framework.git
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655 lines
22 KiB
Python
655 lines
22 KiB
Python
"""
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The :mod:`mixins` module provides a set of reusable `mixin`
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classes that can be added to a `View`.
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"""
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from django.contrib.auth.models import AnonymousUser
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from django.core.paginator import Paginator
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from django.db.models.fields.related import ForeignKey
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from django.db.models.query import Q
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from django.http import HttpResponse
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from urlobject import URLObject
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from djangorestframework import status
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from djangorestframework.renderers import BaseRenderer
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from djangorestframework.resources import Resource, FormResource, ModelResource
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from djangorestframework.response import Response, ErrorResponse
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from djangorestframework.request import request_class_factory
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from djangorestframework.utils import as_tuple, MSIE_USER_AGENT_REGEX
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from djangorestframework.utils.mediatypes import is_form_media_type, order_by_precedence
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__all__ = (
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# Base behavior mixins
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'RequestMixin',
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'ResponseMixin',
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'AuthMixin',
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'ResourceMixin',
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# Reverse URL lookup behavior
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'InstanceMixin',
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# Model behavior mixins
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'ReadModelMixin',
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'CreateModelMixin',
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'UpdateModelMixin',
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'DeleteModelMixin',
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'ListModelMixin'
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)
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########## Request Mixin ##########
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class RequestMixin(object):
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"""
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`Mixin` class to provide request parsing behavior.
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"""
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_USE_FORM_OVERLOADING = True
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_METHOD_PARAM = '_method'
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_CONTENTTYPE_PARAM = '_content_type'
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_CONTENT_PARAM = '_content'
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parsers = ()
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"""
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The set of request parsers that the view can handle.
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Should be a tuple/list of classes as described in the :mod:`parsers` module.
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"""
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def get_request_class(self):
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"""
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Returns a custom subclass of Django's `HttpRequest`, providing new facilities
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such as direct access to the parsed request content.
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"""
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if not hasattr(self, '_request_class'):
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self._request_class = request_class_factory(self.request)
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self._request_class._USE_FORM_OVERLOADING = self._USE_FORM_OVERLOADING
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self._request_class._METHOD_PARAM = self._METHOD_PARAM
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self._request_class._CONTENTTYPE_PARAM = self._CONTENTTYPE_PARAM
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self._request_class._CONTENT_PARAM = self._CONTENT_PARAM
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self._request_class.parsers = self.parsers
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return self._request_class
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def get_request(self):
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"""
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Returns a custom request instance, with data and attributes copied from the
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original request.
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"""
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request_class = self.get_request_class()
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return request_class(self.request)
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########## ResponseMixin ##########
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class ResponseMixin(object):
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"""
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Adds behavior for pluggable `Renderers` to a :class:`views.View` class.
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Default behavior is to use standard HTTP Accept header content negotiation.
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Also supports overriding the content type by specifying an ``_accept=`` parameter in the URL.
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Ignores Accept headers from Internet Explorer user agents and uses a sensible browser Accept header instead.
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"""
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_ACCEPT_QUERY_PARAM = '_accept' # Allow override of Accept header in URL query params
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_IGNORE_IE_ACCEPT_HEADER = True
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renderers = ()
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"""
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The set of response renderers that the view can handle.
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Should be a tuple/list of classes as described in the :mod:`renderers` module.
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"""
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# TODO: wrap this behavior around dispatch(), ensuring it works
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# out of the box with existing Django classes that use render_to_response.
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def render(self, response):
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"""
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Takes a :obj:`Response` object and returns an :obj:`HttpResponse`.
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"""
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self.response = response
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try:
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renderer, media_type = self._determine_renderer(self.request)
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except ErrorResponse, exc:
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renderer = self._default_renderer(self)
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media_type = renderer.media_type
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response = exc.response
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# Set the media type of the response
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# Note that the renderer *could* override it in .render() if required.
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response.media_type = renderer.media_type
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# Serialize the response content
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if response.has_content_body:
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content = renderer.render(response.cleaned_content, media_type)
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else:
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content = renderer.render()
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# Build the HTTP Response
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resp = HttpResponse(content, mimetype=response.media_type, status=response.status)
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for (key, val) in response.headers.items():
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resp[key] = val
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return resp
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def _determine_renderer(self, request):
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"""
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Determines the appropriate renderer for the output, given the client's 'Accept' header,
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and the :attr:`renderers` set on this class.
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Returns a 2-tuple of `(renderer, media_type)`
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See: RFC 2616, Section 14 - http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html
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"""
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if self._ACCEPT_QUERY_PARAM and request.GET.get(self._ACCEPT_QUERY_PARAM, None):
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# Use _accept parameter override
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accept_list = [request.GET.get(self._ACCEPT_QUERY_PARAM)]
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elif (self._IGNORE_IE_ACCEPT_HEADER and
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'HTTP_USER_AGENT' in request.META and
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MSIE_USER_AGENT_REGEX.match(request.META['HTTP_USER_AGENT'])):
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# Ignore MSIE's broken accept behavior and do something sensible instead
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accept_list = ['text/html', '*/*']
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elif 'HTTP_ACCEPT' in request.META:
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# Use standard HTTP Accept negotiation
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accept_list = [token.strip() for token in request.META['HTTP_ACCEPT'].split(',')]
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else:
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# No accept header specified
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accept_list = ['*/*']
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# Check the acceptable media types against each renderer,
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# attempting more specific media types first
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# NB. The inner loop here isn't as bad as it first looks :)
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# Worst case is we're looping over len(accept_list) * len(self.renderers)
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renderers = [renderer_cls(self) for renderer_cls in self.renderers]
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for accepted_media_type_lst in order_by_precedence(accept_list):
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for renderer in renderers:
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for accepted_media_type in accepted_media_type_lst:
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if renderer.can_handle_response(accepted_media_type):
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return renderer, accepted_media_type
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# No acceptable renderers were found
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raise ErrorResponse(status.HTTP_406_NOT_ACCEPTABLE,
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{'detail': 'Could not satisfy the client\'s Accept header',
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'available_types': self._rendered_media_types})
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@property
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def _rendered_media_types(self):
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"""
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Return an list of all the media types that this view can render.
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"""
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return [renderer.media_type for renderer in self.renderers]
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@property
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def _rendered_formats(self):
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"""
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Return a list of all the formats that this view can render.
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"""
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return [renderer.format for renderer in self.renderers]
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@property
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def _default_renderer(self):
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"""
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Return the view's default renderer class.
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"""
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return self.renderers[0]
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########## Auth Mixin ##########
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class AuthMixin(object):
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"""
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Simple :class:`mixin` class to add authentication and permission checking to a :class:`View` class.
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"""
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authentication = ()
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"""
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The set of authentication types that this view can handle.
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Should be a tuple/list of classes as described in the :mod:`authentication` module.
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"""
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permissions = ()
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"""
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The set of permissions that will be enforced on this view.
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Should be a tuple/list of classes as described in the :mod:`permissions` module.
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"""
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@property
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def user(self):
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"""
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Returns the :obj:`user` for the current request, as determined by the set of
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:class:`authentication` classes applied to the :class:`View`.
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"""
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if not hasattr(self, '_user'):
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self._user = self._authenticate()
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return self._user
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def _authenticate(self):
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"""
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Attempt to authenticate the request using each authentication class in turn.
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Returns a ``User`` object, which may be ``AnonymousUser``.
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"""
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for authentication_cls in self.authentication:
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authentication = authentication_cls(self)
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user = authentication.authenticate(self.request)
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if user:
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return user
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return AnonymousUser()
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# TODO: wrap this behavior around dispatch()
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def _check_permissions(self):
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"""
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Check user permissions and either raise an ``ErrorResponse`` or return.
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"""
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user = self.user
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for permission_cls in self.permissions:
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permission = permission_cls(self)
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permission.check_permission(user)
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########## Resource Mixin ##########
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class ResourceMixin(object):
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"""
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Provides request validation and response filtering behavior.
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Should be a class as described in the :mod:`resources` module.
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The :obj:`resource` is an object that maps a view onto it's representation on the server.
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It provides validation on the content of incoming requests,
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and filters the object representation into a serializable object for the response.
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"""
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resource = None
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@property
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def CONTENT(self):
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"""
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Returns the cleaned, validated request content.
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May raise an :class:`response.ErrorResponse` with status code 400 (Bad Request).
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"""
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if not hasattr(self, '_content'):
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self._content = self.validate_request(self.request.DATA, self.request.FILES)
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return self._content
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@property
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def PARAMS(self):
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"""
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Returns the cleaned, validated query parameters.
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May raise an :class:`response.ErrorResponse` with status code 400 (Bad Request).
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"""
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return self.validate_request(self.request.GET)
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@property
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def _resource(self):
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if self.resource:
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return self.resource(self)
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elif getattr(self, 'model', None):
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return ModelResource(self)
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elif getattr(self, 'form', None):
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return FormResource(self)
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elif getattr(self, '%s_form' % self.request.method.lower(), None):
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return FormResource(self)
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return Resource(self)
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def validate_request(self, data, files=None):
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"""
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Given the request *data* and optional *files*, return the cleaned, validated content.
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May raise an :class:`response.ErrorResponse` with status code 400 (Bad Request) on failure.
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"""
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return self._resource.validate_request(data, files)
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def filter_response(self, obj):
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"""
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Given the response content, filter it into a serializable object.
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"""
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return self._resource.filter_response(obj)
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def get_bound_form(self, content=None, method=None):
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if hasattr(self._resource, 'get_bound_form'):
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return self._resource.get_bound_form(content, method=method)
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else:
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return None
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##########
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class InstanceMixin(object):
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"""
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`Mixin` class that is used to identify a `View` class as being the canonical identifier
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for the resources it is mapped to.
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"""
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@classmethod
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def as_view(cls, **initkwargs):
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"""
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Store the callable object on the resource class that has been associated with this view.
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"""
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view = super(InstanceMixin, cls).as_view(**initkwargs)
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resource = getattr(cls(**initkwargs), 'resource', None)
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if resource:
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# We do a little dance when we store the view callable...
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# we need to store it wrapped in a 1-tuple, so that inspect will treat it
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# as a function when we later look it up (rather than turning it into a method).
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# This makes sure our URL reversing works ok.
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resource.view_callable = (view,)
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return view
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########## Model Mixins ##########
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class ModelMixin(object):
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""" Implements mechanisms used by other classes (like *ModelMixin group) to
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define a query that represents Model instances the Mixin is working with.
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If a *ModelMixin is going to retrive an instance (or queryset) using args and kwargs
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passed by as URL arguments, it should provied arguments to objects.get and objects.filter
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methods wrapped in by `build_query`
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If a *ModelMixin is going to create/update an instance get_instance_data
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handles the instance data creation/preaparation.
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"""
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queryset = None
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def build_query(self, *args, **kwargs):
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""" Returns django.db.models.Q object to be used for the objects retrival.
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Arguments:
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- args: unnamed URL arguments
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- kwargs: named URL arguments
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If a URL passes any arguments to the view being the QueryMixin subclass
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build_query manages the arguments and provides the Q object that will be
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used for the objects retrival with filter/get queryset methods.
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Technically, neither args nor kwargs have to be provided, however the default
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behaviour is to map all kwargs as the query constructors so that if this
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method is not overriden only kwargs keys being model fields are valid.
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If positional args are provided, the last one argument is understood
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as the primary key. However this usage should be considered
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deperecated, and will be removed in a future version.
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"""
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tmp = dict(kwargs)
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# If the URLconf includes a .(?P<format>\w+) pattern to match against
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# a .json, .xml suffix, then drop the 'format' kwarg before
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# constructing the query.
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if BaseRenderer._FORMAT_QUERY_PARAM in tmp:
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del tmp[BaseRenderer._FORMAT_QUERY_PARAM]
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if args:
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# If we have any no kwargs then assume the last arg represents the
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# primrary key. Otherwise assume the kwargs uniquely identify the
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# model.
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tmp.update({'pk': args[-1]})
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return Q(**tmp)
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def get_instance_data(self, model, content, **kwargs):
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"""
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Returns the dict with the data for model instance creation/update query.
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Arguments:
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- model: model class (django.db.models.Model subclass) to work with
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- content: a dictionary with instance data
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- kwargs: a dict of URL provided keyword arguments
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The create/update queries are created basicly with the contet provided
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with POST/PUT HTML methods and kwargs passed in the URL. This methods
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simply merges the URL data and the content preaparing the ready-to-use
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data dictionary.
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"""
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tmp = dict(kwargs)
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for field in model._meta.fields:
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if isinstance(field, ForeignKey) and field.name in tmp:
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# translate 'related_field' kwargs into 'related_field_id'
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tmp[field.name + '_id'] = tmp[field.name]
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del tmp[field.name]
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all_kw_args = dict(content.items() + tmp.items())
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return all_kw_args
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def get_object(self, *args, **kwargs):
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"""
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Get the instance object for read/update/delete requests.
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"""
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model = self.resource.model
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return model.objects.get(self.build_query(*args, **kwargs))
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def get_queryset(self):
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"""
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Return the queryset for this view.
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"""
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return getattr(self.resource, 'queryset',
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self.resource.model.objects.all())
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def get_ordering(self):
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"""
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Return the ordering for this view.
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"""
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return getattr(self.resource, 'ordering', None)
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class ReadModelMixin(ModelMixin):
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"""
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Behavior to read a `model` instance on GET requests
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"""
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def get(self, request, *args, **kwargs):
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model = self.resource.model
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try:
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self.model_instance = self.get_object(*args, **kwargs)
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except model.DoesNotExist:
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raise ErrorResponse(status.HTTP_404_NOT_FOUND)
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return self.model_instance
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def build_query(self, *args, **kwargs):
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# Build query is overriden to filter the kwargs priori
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# to use them as build_query argument
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filtered_keywords = kwargs.copy()
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return super(ReadModelMixin, self).build_query(*args, **filtered_keywords)
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class CreateModelMixin(ModelMixin):
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"""
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Behavior to create a `model` instance on POST requests
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"""
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def post(self, request, *args, **kwargs):
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model = self.resource.model
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# Copy the dict to keep self.CONTENT intact
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content = dict(self.CONTENT)
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m2m_data = {}
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for field in model._meta.many_to_many:
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if field.name in content:
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m2m_data[field.name] = (
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field.m2m_reverse_field_name(), content[field.name]
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)
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del content[field.name]
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instance = model(**self.get_instance_data(model, content, *args, **kwargs))
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instance.save()
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for fieldname in m2m_data:
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manager = getattr(instance, fieldname)
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if hasattr(manager, 'add'):
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manager.add(*m2m_data[fieldname][1])
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else:
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data = {}
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data[manager.source_field_name] = instance
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for related_item in m2m_data[fieldname][1]:
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data[m2m_data[fieldname][0]] = related_item
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manager.through(**data).save()
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headers = {}
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if hasattr(instance, 'get_absolute_url'):
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headers['Location'] = self.resource(self).url(instance)
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return Response(status.HTTP_201_CREATED, instance, headers)
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class UpdateModelMixin(ModelMixin):
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"""
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Behavior to update a `model` instance on PUT requests
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"""
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def put(self, request, *args, **kwargs):
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model = self.resource.model
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# TODO: update on the url of a non-existing resource url doesn't work
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# correctly at the moment - will end up with a new url
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try:
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self.model_instance = self.get_object(*args, **kwargs)
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for (key, val) in self.CONTENT.items():
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setattr(self.model_instance, key, val)
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except model.DoesNotExist:
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self.model_instance = model(**self.get_instance_data(model, self.CONTENT, *args, **kwargs))
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self.model_instance.save()
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return self.model_instance
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class DeleteModelMixin(ModelMixin):
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"""
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Behavior to delete a `model` instance on DELETE requests
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"""
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def delete(self, request, *args, **kwargs):
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model = self.resource.model
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try:
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instance = self.get_object(*args, **kwargs)
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except model.DoesNotExist:
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raise ErrorResponse(status.HTTP_404_NOT_FOUND, None, {})
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instance.delete()
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return
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|
|
|
|
|
class ListModelMixin(ModelMixin):
|
|
"""
|
|
Behavior to list a set of `model` instances on GET requests
|
|
"""
|
|
|
|
def get(self, request, *args, **kwargs):
|
|
queryset = self.get_queryset()
|
|
ordering = self.get_ordering()
|
|
|
|
queryset = queryset.filter(self.build_query(**kwargs))
|
|
if ordering:
|
|
queryset = queryset.order_by(*ordering)
|
|
|
|
return queryset
|
|
|
|
|
|
########## Pagination Mixins ##########
|
|
|
|
class PaginatorMixin(object):
|
|
"""
|
|
Adds pagination support to GET requests
|
|
Obviously should only be used on lists :)
|
|
|
|
A default limit can be set by setting `limit` on the object. This will also
|
|
be used as the maximum if the client sets the `limit` GET param
|
|
"""
|
|
limit = 20
|
|
|
|
def get_limit(self):
|
|
"""
|
|
Helper method to determine what the `limit` should be
|
|
"""
|
|
try:
|
|
limit = int(self.request.GET.get('limit', self.limit))
|
|
return min(limit, self.limit)
|
|
except ValueError:
|
|
return self.limit
|
|
|
|
def url_with_page_number(self, page_number):
|
|
"""
|
|
Constructs a url used for getting the next/previous urls
|
|
"""
|
|
url = URLObject.parse(self.request.get_full_path())
|
|
url = url.add_query_param('page', page_number)
|
|
|
|
limit = self.get_limit()
|
|
if limit != self.limit:
|
|
url = url.add_query_param('limit', limit)
|
|
|
|
return url
|
|
|
|
def next(self, page):
|
|
"""
|
|
Returns a url to the next page of results (if any)
|
|
"""
|
|
if not page.has_next():
|
|
return None
|
|
|
|
return self.url_with_page_number(page.next_page_number())
|
|
|
|
def previous(self, page):
|
|
""" Returns a url to the previous page of results (if any) """
|
|
if not page.has_previous():
|
|
return None
|
|
|
|
return self.url_with_page_number(page.previous_page_number())
|
|
|
|
def serialize_page_info(self, page):
|
|
"""
|
|
This is some useful information that is added to the response
|
|
"""
|
|
return {
|
|
'next': self.next(page),
|
|
'page': page.number,
|
|
'pages': page.paginator.num_pages,
|
|
'per_page': self.get_limit(),
|
|
'previous': self.previous(page),
|
|
'total': page.paginator.count,
|
|
}
|
|
|
|
def filter_response(self, obj):
|
|
"""
|
|
Given the response content, paginate and then serialize.
|
|
|
|
The response is modified to include to useful data relating to the number
|
|
of objects, number of pages, next/previous urls etc. etc.
|
|
|
|
The serialised objects are put into `results` on this new, modified
|
|
response
|
|
"""
|
|
|
|
# We don't want to paginate responses for anything other than GET requests
|
|
if self.request.method.upper() != 'GET':
|
|
return self._resource.filter_response(obj)
|
|
|
|
paginator = Paginator(obj, self.get_limit())
|
|
|
|
try:
|
|
page_num = int(self.request.GET.get('page', '1'))
|
|
except ValueError:
|
|
raise ErrorResponse(status.HTTP_404_NOT_FOUND,
|
|
{'detail': 'That page contains no results'})
|
|
|
|
if page_num not in paginator.page_range:
|
|
raise ErrorResponse(status.HTTP_404_NOT_FOUND,
|
|
{'detail': 'That page contains no results'})
|
|
|
|
page = paginator.page(page_num)
|
|
|
|
serialized_object_list = self._resource.filter_response(page.object_list)
|
|
serialized_page_info = self.serialize_page_info(page)
|
|
|
|
serialized_page_info['results'] = serialized_object_list
|
|
|
|
return serialized_page_info
|