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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
def _get_validation_exclusions(obj, pk=None, slug_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.
"""
include = []
if pk:
pk_field = obj._meta.pk
while pk_field.rel:
pk_field = pk_field.rel.to._meta.pk
include.append(pk_field.name)
if slug_field:
include.append(slug_field)
return [field.name for field in obj._meta.fields if field.name not in include]
class CreateModelMixin(object):
"""
Create a model instance.
Should be mixed in with any `GenericAPIView`.
"""
def create(self, request, *args, **kwargs):
serializer = self.get_serializer(data=request.DATA, files=request.FILES)
if serializer.is_valid():
self.pre_save(serializer.object)
self.object = serializer.save(force_insert=True)
self.post_save(self.object, created=True)
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['url']}
except (TypeError, KeyError):
return {}
class ListModelMixin(object):
"""
List a queryset.
Should be mixed in with `MultipleObjectAPIView`.
"""
empty_error = "Empty list and '%(class_name)s.allow_empty' is False."
def list(self, request, *args, **kwargs):
queryset = self.get_queryset()
self.object_list = self.filter_queryset(queryset)
# Default is to allow empty querysets. This can be altered by setting
# `.allow_empty = False`, to raise 404 errors on empty querysets.
allow_empty = self.get_allow_empty()
if not allow_empty and not self.object_list:
class_name = self.__class__.__name__
error_msg = self.empty_error % {'class_name': class_name}
raise Http404(error_msg)
# Pagination size is set by the `.paginate_by` attribute,
# which may be `None` to disable pagination.
page_size = self.get_paginate_by(self.object_list)
if page_size:
packed = self.paginate_queryset(self.object_list, page_size)
paginator, page, queryset, is_paginated = packed
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.
Should be mixed in with `SingleObjectAPIView`.
"""
def retrieve(self, request, *args, **kwargs):
queryset = self.get_queryset()
filtered_queryset = self.filter_queryset(queryset)
self.object = self.get_object(filtered_queryset)
serializer = self.get_serializer(self.object)
return Response(serializer.data)
class UpdateModelMixin(object):
"""
Update a model instance.
Should be mixed in with `SingleObjectAPIView`.
"""
def update(self, request, *args, **kwargs):
partial = kwargs.pop('partial', False)
self.object = None
try:
self.object = self.get_object()
except Http404:
# If this is a PUT-as-create operation, we need to ensure that
# we have relevant permissions, as if this was a POST request.
self.check_permissions(clone_request(request, 'POST'))
created = True
save_kwargs = {'force_insert': True}
success_status_code = status.HTTP_201_CREATED
else:
created = False
save_kwargs = {'force_update': True}
success_status_code = status.HTTP_200_OK
serializer = self.get_serializer(self.object, data=request.DATA,
files=request.FILES, partial=partial)
if serializer.is_valid():
self.pre_save(serializer.object)
self.object = serializer.save(**save_kwargs)
self.post_save(self.object, created=created)
return Response(serializer.data, status=success_status_code)
return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)
def partial_update(self, request, *args, **kwargs):
kwargs['partial'] = True
return self.update(request, *args, **kwargs)
def pre_save(self, obj):
"""
Set any attributes on the object that are implicit in the request.
"""
# pk and/or slug attributes are implicit in the URL.
pk = self.kwargs.get(self.pk_url_kwarg, None)
slug = self.kwargs.get(self.slug_url_kwarg, None)
slug_field = slug and self.get_slug_field() or None
if pk:
setattr(obj, 'pk', pk)
if slug:
setattr(obj, slug_field, slug)
# 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, pk, slug_field)
obj.full_clean(exclude)
class DestroyModelMixin(object):
"""
Destroy a model instance.
Should be mixed in with `SingleObjectAPIView`.
"""
def destroy(self, request, *args, **kwargs):
obj = self.get_object()
obj.delete()
return Response(status=status.HTTP_204_NO_CONTENT)
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