DRF终极封装ViewSet和Router附教程PDF源码

在DRF官方教程的学习过程中，一个很明显的感受是框架在不断地进行封装，我们自己写框架/工具/脚本/平台也可以模仿模仿，先完成底层代码，再做多层封装，让使用者很容易就上手操作。本文是教程的最后一篇，介绍ViewSets和Routers。

ViewSets

先看看之前在给User模型创建Endpoint时，我们新增的2个视图：

class UserList(generics.ListAPIView): queryset = User.objects.all() serializer_class = UserSerializer class UserDetail(generics.RetrieveAPIView): queryset = User.objects.all() serializer_class = UserSerializer

DRF提供了rest_framework.viewsets：

可以把它们合成一个视图。

set是集合的意思，ViewSets就是视图集合。

ReadOnlyModelViewSet

我们先使用ReadOnlyModelViewSet把UserList和UserDetail视图合并成一个UserViewSet：

from rest_framework import viewsets class UserViewSet(viewsets.ReadOnlyModelViewSet): """ This viewset automatically provides `list` and `retrieve` actions. """ queryset = User.objects.all() serializer_class = UserSerializer

viewsets.ReadOnlyModelViewSet是只读视图集合，源码如下：

class ReadOnlyModelViewSet(mixins.RetrieveModelMixin, mixins.ListModelMixin, GenericViewSet): """ A viewset that provides default `list()` and `retrieve()` actions. """ pass

它继承了mixins.RetrieveModelMixin、mixins.ListModelMixin和GenericViewSet：

mixins.RetrieveModelMixin

class RetrieveModelMixin: """ Retrieve a model instance. """ def retrieve(self, request, *args, **kwargs): instance = self.get_object() serializer = self.get_serializer(instance) return Response(serializer.data)

mixins.ListModelMixin

class ListModelMixin: """ 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)

viewsets.GenericViewSet

class GenericViewSet(ViewSetMixin, generics.GenericAPIView): """ The GenericViewSet class does not provide any actions by default, but does include the base set of generic view behavior, such as the `get_object` and `get_queryset` methods. """ pass

从源码可以看出，它提供了list()和retrieve()2个方法，正好对应UserList和UserDetail。

ModelViewSet

再使用ModelViewSet把SnippetList、SnippetDetail和SnippetHighlight视图合并成一个SnippetViewSet：

from rest_framework.decorators import action from rest_framework.response import Response from rest_framework import permissions class SnippetViewSet(viewsets.ModelViewSet): """ This viewset automatically provides `list`, `create`, `retrieve`, `update` and `destroy` actions. Additionally we also provide an extra `highlight` action. """ queryset = Snippet.objects.all() serializer_class = SnippetSerializer permission_classes = [permissions.IsAuthenticatedOrReadOnly, IsOwnerOrReadOnly] @action(detail=True, renderer_classes=[renderers.StaticHTMLRenderer]) def highlight(self, request, *args, **kwargs): snippet = self.get_object() return Response(snippet.highlighted) def perform_create(self, serializer): serializer.save(owner=self.request.user)

@action装饰器用来创建除了create/update/delete以外的action，默认为GET请求，如果想改为POST请求，可以添加参数methods，它的源码如下：

def action(methods=None, detail=None, url_path=None, url_name=None, **kwargs): """ Mark a ViewSet method as a routable action. `@action`-decorated functions will be endowed with a `mapping` property, a `MethodMapper` that can be used to add additional method-based behaviors on the routed action. :param methods: A list of HTTP method names this action responds to. Defaults to GET only. :param detail: Required. Determines whether this action applies to instance/detail requests or collection/list requests. :param url_path: Define the URL segment for this action. Defaults to the name of the method decorated. :param url_name: Define the internal (`reverse`) URL name for this action. Defaults to the name of the method decorated with underscores replaced with dashes. :param kwargs: Additional properties to set on the view. This can be used to override viewset-level *_classes settings, equivalent to how the `@renderer_classes` etc. decorators work for function- based API views. """ methods = ['get'] if (methods is None) else methods methods = [method.lower() for method in methods] assert detail is not None, ( "@action() missing required argument: 'detail'" ) # name and suffix are mutually exclusive if 'name' in kwargs and 'suffix' in kwargs: raise TypeError("`name` and `suffix` are mutually exclusive arguments.") def decorator(func): func.mapping = MethodMapper(func, methods) func.detail = detail func.url_path = url_path if url_path else func.__name__ func.url_name = url_name if url_name else func.__name__.replace('_', '-') # These kwargs will end up being passed to `ViewSet.as_view()` within # the router, which eventually delegates to Django's CBV `View`, # which assigns them as instance attributes for each request. func.kwargs = kwargs # Set descriptive arguments for viewsets if 'name' not in kwargs and 'suffix' not in kwargs: func.kwargs['name'] = pretty_name(func.__name__) func.kwargs['description'] = func.__doc__ or None return func return decorator