Django rest framework （视图类详解）

官网：https://www.django-rest-framework.org/api-guide/viewsets/

在django rest framework 视图中一共有N个类

第一类：APIview

class IndexView(APIView): def get(self,request,*args,**kwargs): pk = kwargs.get('pk') if pk: queryset = models.UserInfo.objects.get(pk=pk) ser = UserInfoSerializer(instance=queryset,many=False) else: queryset = models.UserInfo.objects.all() ser = UserInfoSerializer(instance=queryset,many=True) return Response(ser.data) #

这种直接继承了APIView，是最原始的。请求方式就是那五种，get,post,put,patch,delete

第二类 GenericAPIView

class IndexView(GenericAPIView): queryset = models.UserInfo.objects.all() serializer_class = UserInfoSerializer lookup_field = 'pk' def get(self,request,*args,**kwargs): pk = kwargs.get('pk') if pk: users = self.filter_queryset(queryset=models.UserInfo.objects.get(pk=pk)) ser = self.get_serializer(instance=users) else: users = self.get_queryset() ser = self.get_serializer(instance=users,many=True) return Response(ser.data)

在GenericAPIView中要重写一些字段和方法，不常用。

第三类 GenericViewSet

class IndexView(GenericViewSet): serializer_class = UserInfoSerializer queryset = models.UserInfo.objects.all() def create(self,request,*args,**kwargs): pass def list(self,request,*args,**kwargs): # 获取列表数据 users = models.UserInfo.objects.all() ser = UserInfoSerializer(instance=users,many=True) return Response(ser.data) def retrieve(self,request,*args,**kwargs): # 获取单条数据 pk = kwargs.get('pk') users = models.UserInfo.objects.get(pk=pk) ser = UserInfoSerializer(instance=users,many=False) return Response(ser.data) def destroy(self,request,*args,**kwargs): pass def update(self,request,*args,**kwargs): pass def partial_update(self,request,*args,**kwargs): pass

这个类继承了ViewSetMixin, generics.GenericAPIView，其中在ViewSetMixin中会重写as_view()方法，因此可以将URL中的请求方式与视图函数绑定到一起，在urls.py中以键值对的方式存在： urls.py

from django.conf.urls import url from django.contrib import admin from app01 import views urlpatterns = [ # url(r'^admin/', admin.site.urls), url(r'^hehe/', views.hehe), url(r'^index/$', views.IndexView.as_view({'get':'list','post':'create'})), url(r'^index/(?P<pk>\d+)/$', views.IndexView.as_view({'get':'retrieve','put':'update','patch':'partial_update','delete':'destroy'})), ]

ViewSetMixin源码部分：

class ViewSetMixin(object): """ This is the magic. Overrides `.as_view()` so that it takes an `actions` keyword that performs the binding of HTTP methods to actions on the Resource. For example, to create a concrete view binding the 'GET' and 'POST' methods to the 'list' and 'create' actions... view = MyViewSet.as_view({'get': 'list', 'post': 'create'}) """ @classonlymethod def as_view(cls, actions=None, **initkwargs): """ Because of the way class based views create a closure around the instantiated view, we need to totally reimplement `.as_view`, and slightly modify the view function that is created and returned. """ # The suffix initkwarg is reserved for displaying the viewset type. # eg. 'List' or 'Instance'. cls.suffix = None # Setting a basename allows a view to reverse its action urls. This # value is provided by the router through the initkwargs. cls.basename = None # actions must not be empty if not actions: raise TypeError("The `actions` argument must be provided when " "calling `.as_view()` on a ViewSet. For example " "`.as_view({'get': 'list'})`") # sanitize keyword arguments for key in initkwargs: if key in cls.http_method_names: raise TypeError("You tried to pass in the %s method name as a " "keyword argument to %s(). Don't do that." % (key, cls.__name__)) if not hasattr(cls, key): raise TypeError("%s() received an invalid keyword %r" % ( cls.__name__, key)) def view(request, *args, **kwargs): self = cls(**initkwargs) # We also store the mapping of request methods to actions, # so that we can later set the action attribute. # eg. `self.action = 'list'` on an incoming GET request. self.action_map = actions # Bind methods to actions # This is the bit that's different to a standard view for method, action in actions.items(): handler = getattr(self, action) # 通过反射获取请求方式 setattr(self, method, handler) # 绑定到视图函数中的方法 if hasattr(self, 'get') and not hasattr(self, 'head'): self.head = self.get self.request = request self.args = args self.kwargs = kwargs # And continue as usual return self.dispatch(request, *args, **kwargs) # take name and docstring from class update_wrapper(view, cls, updated=()) # and possible attributes set by decorators # like csrf_exempt from dispatch update_wrapper(view, cls.dispatch, assigned=()) # We need to set these on the view function, so that breadcrumb # generation can pick out these bits of information from a # resolved URL. view.cls = cls view.initkwargs = initkwargs view.suffix = initkwargs.get('suffix', None) view.actions = actions return csrf_exempt(view) def initialize_request(self, request, *args, **kwargs): """ Set the `.action` attribute on the view, depending on the request method. """ request = super(ViewSetMixin, self).initialize_request(request, *args, **kwargs) method = request.method.lower() if method == 'options': # This is a special case as we always provide handling for the # options method in the base `View` class. # Unlike the other explicitly defined actions, 'metadata' is implicit. self.action = 'metadata' else: self.action = self.action_map.get(method) return request def reverse_action(self, url_name, *args, **kwargs): """ Reverse the action for the given `url_name`. """ url_name = '%s-%s' % (self.basename, url_name) kwargs.setdefault('request', self.request) return reverse(url_name, *args, **kwargs)

第四类 ModelViewSet 继承了这个类，ModelViewSet继承了四个混入类和一个泛类，

将会获得增删改查的所有方法。

class IndexView(ModelViewSet): queryset = models.UserInfo.objects.all() serializer_class = UserInfoSerializer class ModelViewSet(mixins.CreateModelMixin, mixins.RetrieveModelMixin, mixins.UpdateModelMixin, mixins.DestroyModelMixin, mixins.ListModelMixin, GenericViewSet): """ A viewset that provides default `create()`, `retrieve()`, `update()`, `partial_update()`, `destroy()` and `list()` actions. """ pass

使用类视图的好处： 1、我们将各个HTTP请求方法之间，做了更好的分离。 2、可以很容易地，组成可重复使用的行为。