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"""
Basic building blocks for generic class based views.
We don't bind behaviour to http method handlers yet,
which allows mixin classes to be composed in interesting ways.
"""
from __future__ import unicode_literals
from django.http import Http404
from rest_framework import status
from rest_framework.response import Response
from rest_framework.request import clone_request
from rest_framework.settings import api_settings
def _get_validation_exclusions(obj, lookup_field=None):
"""
Given a model instance, and an optional pk and slug field,
return the full list of all other field names on that model.
For use when performing full_clean on a model instance,
so we only clean the required fields.
"""
if lookup_field == 'pk':
pk_field = obj._meta.pk
while pk_field.rel:
pk_field = pk_field.rel.to._meta.pk
lookup_field = pk_field.name
return [field.name for field in obj._meta.fields if field.name != lookup_field]
class CreateModelMixin(object):
"""
Create a model instance.
"""
def create(self, request, *args, **kwargs):
serializer = self.get_serializer(data=request.DATA)
if serializer.is_valid():
self.object = serializer.save()
headers = self.get_success_headers(serializer.data)
return Response(serializer.data, status=status.HTTP_201_CREATED,
headers=headers)
return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)
def get_success_headers(self, data):
try:
return {'Location': data[api_settings.URL_FIELD_NAME]}
except (TypeError, KeyError):
return {}
class ListModelMixin(object):
"""
List a queryset.
"""
def list(self, request, *args, **kwargs):
self.object_list = self.filter_queryset(self.get_queryset())
# Switch between paginated or standard style responses
page = self.paginate_queryset(self.object_list)
if page is not None:
serializer = self.get_pagination_serializer(page)
else:
serializer = self.get_serializer(self.object_list, many=True)
return Response(serializer.data)
class RetrieveModelMixin(object):
"""
Retrieve a model instance.
"""
def retrieve(self, request, *args, **kwargs):
self.object = self.get_object()
serializer = self.get_serializer(self.object)
return Response(serializer.data)
class UpdateModelMixin(object):
"""
Update a model instance.
"""
def update(self, request, *args, **kwargs):
partial = kwargs.pop('partial', False)
self.object = self.get_object_or_none()
serializer = self.get_serializer(self.object, data=request.DATA, partial=partial)
if not serializer.is_valid():
return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)
lookup_url_kwarg = self.lookup_url_kwarg or self.lookup_field
lookup_value = self.kwargs[lookup_url_kwarg]
extras = {self.lookup_field: lookup_value}
if self.object is None:
self.object = serializer.save(extras=extras)
return Response(serializer.data, status=status.HTTP_201_CREATED)
self.object = serializer.save(extras=extras)
return Response(serializer.data, status=status.HTTP_200_OK)
def partial_update(self, request, *args, **kwargs):
kwargs['partial'] = True
return self.update(request, *args, **kwargs)
def get_object_or_none(self):
try:
return self.get_object()
except Http404:
if self.request.method == 'PUT':
# For PUT-as-create operation, we need to ensure that we have
# relevant permissions, as if this was a POST request. This
# will either raise a PermissionDenied exception, or simply
# return None.
self.check_permissions(clone_request(self.request, 'POST'))
else:
# PATCH requests where the object does not exist should still
# return a 404 response.
raise
def pre_save(self, obj):
"""
Set any attributes on the object that are implicit in the request.
"""
lookup_url_kwarg = self.lookup_url_kwarg or self.lookup_field
lookup_value = self.kwargs[lookup_url_kwarg]
setattr(obj, self.lookup_field, lookup_value)
# Ensure we clean the attributes so that we don't eg return integer
# pk using a string representation, as provided by the url conf kwarg.
if hasattr(obj, 'full_clean'):
exclude = _get_validation_exclusions(obj, self.lookup_field)
obj.full_clean(exclude)
class DestroyModelMixin(object):
"""
Destroy a model instance.
"""
def destroy(self, request, *args, **kwargs):
obj = self.get_object()
self.pre_delete(obj)
obj.delete()
self.post_delete(obj)
return Response(status=status.HTTP_204_NO_CONTENT)
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