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

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==1.8.8djangorestframework==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=headersclass 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 CourseSerializerdef 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。