Django REST framework的各类技巧——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的各类技巧【目录索引】

写在上面

全部的代码都是在下面的两个版原本作的

django==1.8.8
djangorestframework==3.2.5

一个以前的blog，解释django generic view Django generics view 以及看源码为何这么重要

一组标准的api的实现实现

例若有一个课程类的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？

能够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

根据继承关系能够先看下ListCreateAPIView,能够看到他提供了get post两个方法，你固然能够直接重写这两个方法，然而就不能用他不少内置的东东，因此重写这里并很差，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)

咱们已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)

因此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能够实现继续的filter

其余的各类mixin各位同窗本身看代码就知道了，触类旁通我再也不赘述。