Django REST framework的各种技巧——4.Generic View

generic view是django神奇的地方，而restframework遵循了这个powerful的机制

Django REST framework的各种技巧【目录索引】

写在上面

所有的代码都是在下面的两个版本来做的

django==1.8.8
djangorestframework==3.2.5

一个之前的blog，解释django generic view
Django generics view 以及看源码为什么这么重要

一组标准的api的实现实现

例如有一个课程类的api，支持增删改查

url

url(r'^courses/$', CoursesView.as_view(), name='course-list'),
url(r'^course/(?P<pk>\d+)/$', CourseDetailView.as_view(), name='course-detail'),

view

class CoursesView(ListCreateAPIView):

filter_backends = (SchoolPermissionFilterBackend, filters.DjangoFilterBackend, filters.SearchFilter)
permission_classes = (IsAuthenticated, ModulePermission)
queryset = Course.objects.filter(is_active=True).order_by('-id')
filter_fields = ('term',)
search_fields = ('name', 'teacher', 'school__name')
module_perms = ['course.course']

def get_serializer_class(self):
if self.request.method in SAFE_METHODS:
return CourseFullMessageSerializer
else:
return CourseSerializer

def get_queryset(self):
return Course.objects.select_related('school', ).filter(
is_active=True, school__is_active=True, term__is_active=True).order_by('-id')

@POST('school', validators='required')
def create(self, request, school, *args, **kwargs):
if not SchoolPermissionFilterBackend().has_school_permission(request.user, school):
raise Error(errors.PermissionDenied, err_message=u'没有对应学校的权限', message=u'没有对应学校的权限')
serializer = self.get_serializer(data=request.data)
serializer.is_valid(raise_exception=True)
self.perform_create(serializer)
headers = self.get_success_headers(serializer.data)
return Response(CourseFullMessageSerializer(serializer.instance).data, status=status.HTTP_201_CREATED, headers=headers

class CourseDetailView(UnActiveModelMixin, DeleteForeignObjectRelModelMixin, RetrieveUpdateDestroyAPIView):

filter_backends = [SchoolPermissionFilterBackend,]
serializer_class = CourseSerializer
permission_classes = (IsAuthenticated, ModulePermission)
queryset = Course.objects.filter(is_active=True).order_by('-id')
module_perms = ['course.course']

def get_serializer_class(self):
if self.request.method in SAFE_METHODS:
return CourseFullMessageSerializer
else:
return CourseSerializer
def retrieve(self, request, *args, **kwargs):
instance = self.get_object()
school = instance.school
if not SchoolPermissionFilterBackend().has_school_permission(request.user, school):
raise Error(errors.PermissionDenied, err_message=u'没有对应学校的权限', message=u'没有对应学校的权限')
serializer = self.get_serializer(instance)
return Response(serializer.data)

@POST('school', validators='required')
def update(self, request, school, *args, **kwargs):
if not SchoolPermissionFilterBackend().has_school_permission(request.user, school):
raise Error(errors.PermissionDenied, err_message=u'没有对应学校的权限', message=u'没有对应学校的权限')
partial = kwargs.pop('partial', False)
instance = self.get_object()
serializer = self.get_serializer(instance, data=request.data, partial=partial)
serializer.is_valid(raise_exception=True)
self.perform_update(serializer)
return Response(CourseFullMessageSerializer(serializer.instance).data)

def destroy(self, request, *args, **kwargs):
instance = self.get_object()
school = instance.school
if not SchoolPermissionFilterBackend().has_school_permission(request.user, school):
raise Error(errors.PermissionDenied, err_message=u'没有对应学校的权限', message=u'没有对应学校的权限')
return super(CourseDetailView, self).destroy(request, *args, **kwargs)

怎么知道重写什么方法？

可以看到我根据需求重写了一些方法，那么到底应该重写那些方法呢？
cd 你的virtualevn/local/lib/python2.7/site-packages/rest_framework
请看下面两个文件
generics.py
mixins.py

根据继承关系可以先看下ListCreateAPIView,可以看到他提供了get post两个方法，你当然可以直接重写这两个方法，然而就不能用他很多内置的东东，所以重写这里并不好，而应该看他对应的mixin

class ListCreateAPIView(mixins.ListModelMixin,
mixins.CreateModelMixin,
GenericAPIView):
"""
Concrete view for listing a queryset or creating a model instance.
"""
def get(self, request, *args, **kwargs):
return self.list(request, *args, **kwargs)

def post(self, request, *args, **kwargs):
return self.create(request, *args, **kwargs)

我们已get为例，get中return self.list(request, *args, **kwargs)，而这个东东是mixins.ListModelMixin里面的方法

class ListModelMixin(object):
"""
List a queryset.
"""
def list(self, request, *args, **kwargs):
queryset = self.filter_queryset(self.get_queryset())

page = self.paginate_queryset(queryset)
if page is not None:
serializer = self.get_serializer(page, many=True)
return self.get_paginated_response(serializer.data)

serializer = self.get_serializer(queryset, many=True)
return Response(serializer.data)

所以在这里你就知道为嘛restframework在class上要定义一个queryset或者实现get_queryset方法（请继续看generic view的代码部分，我不贴了），为嘛class上定义一个filter_backends可以实现继续的filter

其他的各种mixin各位同学自己看代码就知道了，举一反三我不再赘述。