drf之视图类与路由

视图

Django REST framwork 提供的视图的主要作用:

  • 控制序列化器的执行(检验、保存、转换数据)
  • 控制数据库查询的执行

2个视图基类

APIView

rest_framework.views.APIView
APIViewView
APIViewView
RequestHttpRequesetResponseAPIException

支持定义的属性

  • authentication_classes 列表或元祖,身份认证类
  • permissoin_classes 列表或元祖,权限检查类
  • throttle_classes 列表或元祖,流量控制类
APIView

举例:

from rest_framework.views import APIView
from rest_framework.response import Response

url(r‘^books/$’, views.BookListView.as_view()),

class BookListView(APIView):

def get(self, request):<br/>
    books = BookInfo.objects.all()<br/>
    serializer = BookInfoSerializer(books, many=True)<br/>
    return Response(serializer.data)<br/>

GenericAPIView[通用视图类]

rest_framework.generics.GenericAPIView
APIVIew

提供的关于序列化器使用的属性与方法

def get_serializer_class(self):

if self.request.user.is_staff:<br/>
    return FullAccountSerializer<br/>
return BasicAccountSerializer<br/>

提供的关于数据库查询的属性与方法

def get_queryset(self):

user = self.request.user<br/>
return user.accounts.all()<br/>

# url(r‘^books/(?P&lt;pk&gt;\d+)/$’, views.BookDetailView.as_view()),
class BookDetailView(GenericAPIView):

queryset = BookInfo.objects.all()<br/>
serializer_class = BookInfoSerializer

def get(self, request, pk):

    book = self.get_object() # get_object()方法根据pk参数查找queryset中的数据对象<br/>
    serializer = self.get_serializer(book)<br/>
    return Response(serializer.data)<br/>

其他可以设置的属性

  • pagination_class 指明分页控制类
  • filter_backends 指明过滤控制后端

5个视图扩展类

作用:

提供了几种后端视图(对数据资源进行曾删改查)处理流程的实现,如果需要编写的视图属于这五种,则视图可以通过继承相应的扩展类来复用代码,减少自己编写的代码量。

这五个扩展类需要搭配GenericAPIView父类,因为五个扩展类的实现需要调用GenericAPIView提供的序列化器与数据库查询的方法。

1)ListModelMixin

list(request, *args, **kwargs)

该Mixin的list方法会对数据进行过滤和分页。

源代码:

class ListModelMixin(object):

&#34;&#34;&#34;<br/>
List a queryset.<br/>
&#34;&#34;&#34;<br/>
def list(self, request, *args, **kwargs):<br/>
    # 过滤<br/>
    queryset = self.filter_queryset(self.get_queryset())<br/>
    # 分页<br/>
    page = self.paginate_queryset(queryset)<br/>
    if page is not None:<br/>
        serializer = self.get_serializer(page, many=True)<br/>
        return self.get_paginated_response(serializer.data)<br/>
    # 序列化<br/>
    serializer = self.get_serializer(queryset, many=True)<br/>
    return Response(serializer.data)<br/>

举例:

from rest_framework.mixins import ListModelMixin
class BookListView(ListModelMixin, GenericAPIView):

queryset = BookInfo.objects.all()<br/>
serializer_class = BookInfoSerializer

def get(self, request):

    return self.list(request)<br/>

2)CreateModelMixin

create(request, *args, **kwargs)

如果序列化器对前端发送的数据验证失败,返回400错误。

源代码:

class CreateModelMixin(object):

&#34;&#34;&#34;<br/>
Create a model instance.<br/>
&#34;&#34;&#34;<br/>
def create(self, request, *args, **kwargs):<br/>
    # 获取序列化器<br/>
    serializer = self.get_serializer(data=request.data)<br/>
    # 验证<br/>
    serializer.is_valid(raise_exception=True)<br/>
    # 保存<br/>
    self.perform_create(serializer)<br/>
    headers = self.get_success_headers(serializer.data)<br/>
    return Response(serializer.data, status=status.HTTP_201_CREATED, headers=headers)

def perform_create(self, serializer):

    serializer.save()

def get_success_headers(self, data):

    try:<br/>
        return {&#39;Location&#39;: str(data[api_settings.URL_FIELD_NAME])}<br/>
    except (TypeError, KeyError):<br/>
        return {}<br/>

3) RetrieveModelMixin

retrieve(request, *args, **kwargs)

如果存在,返回200, 否则返回404。

源代码:

class RetrieveModelMixin(object):

&#34;&#34;&#34;<br/>
Retrieve a model instance.<br/>
&#34;&#34;&#34;<br/>
def retrieve(self, request, *args, **kwargs):<br/>
    # 获取对象,会检查对象的权限<br/>
    instance = self.get_object()<br/>
    # 序列化<br/>
    serializer = self.get_serializer(instance)<br/>
    return Response(serializer.data)<br/>

举例:

class BookDetailView(RetrieveModelMixin, GenericAPIView):

queryset = BookInfo.objects.all()<br/>
serializer_class = BookInfoSerializer

def get(self, request, pk):

    return self.retrieve(request)<br/>

4)UpdateModelMixin

update(request, *args, **kwargs)
partial_update(request, *args, **kwargs)

成功返回200,序列化器校验数据失败时,返回400错误。

源代码:

class UpdateModelMixin(object):

&#34;&#34;&#34;<br/>
Update a model instance.<br/>
&#34;&#34;&#34;<br/>
def update(self, request, *args, **kwargs):<br/>
    partial = kwargs.pop(&#39;partial&#39;, False)<br/>
    instance = self.get_object()<br/>
    serializer = self.get_serializer(instance, data=request.data, partial=partial)<br/>
    serializer.is_valid(raise_exception=True)<br/>
    self.perform_update(serializer)

if getattr(instance, ‘_prefetched_objects_cache’, None):

        # If &#39;prefetch_related&#39; has been applied to a queryset, we need to<br/>
        # forcibly invalidate the prefetch cache on the instance.<br/>
        instance._prefetched_objects_cache = {}

return Response(serializer.data) def perform_update(self, serializer):

    serializer.save()

def partial_update(self, request, *args, **kwargs):

    kwargs[&#39;partial&#39;] = True<br/>
    return self.update(request, *args, **kwargs)<br/>

5)DestroyModelMixin

destroy(request, *args, **kwargs)

成功返回204,不存在返回404。

源代码:

class DestroyModelMixin(object):

&#34;&#34;&#34;<br/>
Destroy a model instance.<br/>
&#34;&#34;&#34;<br/>
def destroy(self, request, *args, **kwargs):<br/>
    instance = self.get_object()<br/>
    self.perform_destroy(instance)<br/>
    return Response(status=status.HTTP_204_NO_CONTENT)

def perform_destroy(self, instance):

    instance.delete()<br/>

几个子类视图

1)CreateAPIView

提供 post 方法

继承自: GenericAPIView、CreateModelMixin

2)ListAPIView

提供 get 方法

继承自:GenericAPIView、ListModelMixin

3)RetrieveAPIView

提供 get 方法

继承自: GenericAPIView、RetrieveModelMixin

4)DestoryAPIView

提供 delete 方法

继承自:GenericAPIView、DestoryModelMixin

5)UpdateAPIView

提供 put 和 patch 方法

继承自:GenericAPIView、UpdateModelMixin

6)RetrieveUpdateAPIView

提供 get、put、patch方法

继承自: GenericAPIView、RetrieveModelMixin、UpdateModelMixin

7)RetrieveUpdateDestoryAPIView

提供 get、put、patch、delete方法

继承自:GenericAPIView、RetrieveModelMixin、UpdateModelMixin、DestoryModelMixin

视图集ViewSet

使用视图集ViewSet,可以将一系列逻辑相关的动作放到一个类中:

  • list() 提供一组数据
  • retrieve() 提供单个数据
  • create() 创建数据
  • update() 保存数据
  • destory() 删除数据

ViewSet视图集类不再实现get()、post()等方法,而是实现动作 action 如 list() 、create() 等。

视图集只在使用as_view()方法的时候,才会将action动作与具体请求方式对应上。如:

class BookInfoViewSet(viewsets.ViewSet):
def list(self, request):

    books = BookInfo.objects.all()<br/>
    serializer = BookInfoSerializer(books, many=True)<br/>
    return Response(serializer.data)

def retrieve(self, request, pk=None):

    try:<br/>
        books = BookInfo.objects.get(id=pk)<br/>
    except BookInfo.DoesNotExist:<br/>
        return Response(status=status.HTTP_404_NOT_FOUND)<br/>
    serializer = BookInfoSerializer(books)<br/>
    return Response(serializer.data)<br/>

在设置路由时,我们可以如下操作

urlpatterns = [

url(r&#39;^books/$&#39;, BookInfoViewSet.as_view({&#39;get&#39;:&#39;list&#39;}),<br/>
url(r&#39;^books/(?P&lt;pk&gt;\d+)/$&#39;, BookInfoViewSet.as_view({&#39;get&#39;: &#39;retrieve&#39;})<br/>

]

常用视图集父类

1) ViewSet

APIViewViewSetMixin

ViewSet主要通过继承ViewSetMixin来实现在调用as_view()时传入字典(如{‘get’:‘list’})的映射处理工作。

在ViewSet中,没有提供任何动作action方法,需要我们自己实现action方法。

2)GenericViewSet

GenericAPIViewGenericAPIView
GenericAPIViewViewSetMixin{‘get’:‘list’}GenericAPIView

举例:

from rest_framework import mixins
from rest_framework.viewsets import GenericViewSet
from rest_framework.decorators import action class BookInfoViewSet(mixins.ListModelMixin, mixins.RetrieveModelMixin, GenericViewSet):

queryset = BookInfo.objects.all()<br/>
serializer_class = BookInfoSerializer<br/>

url的定义

urlpatterns = [

url(r&#39;^books/$&#39;, views.BookInfoViewSet.as_view({&#39;get&#39;: &#39;list&#39;})),<br/>
url(r&#39;^books/(?P&lt;pk&gt;\d+)/$&#39;, views.BookInfoViewSet.as_view({&#39;get&#39;: &#39;retrieve&#39;})),<br/>

]

3)ModelViewSet

GenericViewSet

4)ReadOnlyModelViewSet

GenericViewSet

视图集中定义附加action动作

在视图集中,除了上述默认的方法动作外,还可以添加自定义动作。

举例:

from rest_framework import mixins
from rest_framework.viewsets import GenericViewSet
from rest_framework.decorators import action class BookInfoViewSet(mixins.ListModelMixin, mixins.RetrieveModelMixin, GenericViewSet):

queryset = BookInfo.objects.all()<br/>
serializer_class = BookInfoSerializer

def latest(self, request):

    &#34;&#34;&#34;<br/>
    返回最新的图书信息<br/>
    &#34;&#34;&#34;<br/>
    book = BookInfo.objects.latest(&#39;id&#39;)<br/>
    serializer = self.get_serializer(book)<br/>
    return Response(serializer.data)

def read(self, request, pk):

    &#34;&#34;&#34;<br/>
    修改图书的阅读量数据<br/>
    &#34;&#34;&#34;<br/>
    book = self.get_object()<br/>
    book.bread = request.data.get(&#39;read&#39;)<br/>
    book.save()<br/>
    serializer = self.get_serializer(book)<br/>
    return Response(serializer.data)<br/>

url的定义

urlpatterns = [

url(r&#39;^books/$&#39;, views.BookInfoViewSet.as_view({&#39;get&#39;: &#39;list&#39;})),<br/>
url(r&#39;^books/latest/$&#39;, views.BookInfoViewSet.as_view({&#39;get&#39;: &#39;latest&#39;})),<br/>
url(r&#39;^books/(?P&lt;pk&gt;\d+)/$&#39;, views.BookInfoViewSet.as_view({&#39;get&#39;: &#39;retrieve&#39;})),<br/>
url(r&#39;^books/(?P&lt;pk&gt;\d+)/read/$&#39;, views.BookInfoViewSet.as_view({&#39;put&#39;: &#39;read&#39;})),<br/>

]

action属性

在视图集中,我们可以通过action对象属性来获取当前请求视图集时的action动作是哪个。

例如:

from rest_framework.viewsets import ModelViewSet,ReadOnlyModelViewSet
from booktest.models import BookInfo
from .serializers import BookInfoModelSerializer
from rest_framework.response import Response
class BookInfoModelViewSet(ModelViewSet):

queryset = BookInfo.objects.all()<br/>
serializer_class = BookInfoModelSerializer

def get_top_5(self,request):

    &#34;&#34;&#34;获取评论值最多的5条数据&#34;&#34;&#34;<br/>
    # 操作数据库<br/>
    print(self.action) # 获取本次请求的视图方法名

通过路由访问到当前方法中.可以看到本次的action就是请求的方法名

路由Routers

对于视图集ViewSet,我们除了可以自己手动指明请求方式与动作action之间的对应关系外,还可以使用Routers来帮助我们快速实现路由信息。

REST framework提供了两个router

  • SimpleRouter
  • DefaultRouter

使用方法

1) 创建router对象,并注册视图集,例如

from rest_framework import routers
router = routers.SimpleRouter()
router.register(r‘books’, BookInfoViewSet, base_name=‘book’)

register(prefix, viewset, base_name)

  • prefix 该视图集的路由前缀
  • viewset 视图集
  • base_name 路由名称的前缀

如上述代码会形成的路由如下:

^books/\(    name: book-list<br/>
^books/{pk}/\)   name: book-detail

2)添加路由数据

可以有两种方式:

urlpatterns = [

...<br/>

]
urlpatterns += router.urls

urlpatterns = [

...<br/>
url(r&#39;^&#39;, include(router.urls))<br/>

]

视图集中附加action的声明

rest_framework.decorators.action

以action装饰器装饰的方法名会作为action动作名,与list、retrieve等同。

action装饰器可以接收两个参数:

xxx/&lt;pk&gt;/action方法名/

举例:

from rest_framework import mixins
from rest_framework.viewsets import GenericViewSet
from rest_framework.decorators import action class BookInfoViewSet(mixins.ListModelMixin, mixins.RetrieveModelMixin, GenericViewSet):

queryset = BookInfo.objects.all()<br/>
serializer_class = BookInfoSerializer

detail为False 表示路径名格式应该为 books/latest/

@action(methods=[&#39;get&#39;], detail=False)<br/>
def latest(self, request):<br/>
    &#34;&#34;&#34;<br/>
    返回最新的图书信息<br/>
    &#34;&#34;&#34;<br/>
    ...

detail为True,表示路径名格式应该为 books/{pk}/read/

@action(methods=[&#39;put&#39;], detail=True)<br/>
def read(self, request, pk):<br/>
    &#34;&#34;&#34;<br/>
    修改图书的阅读量数据<br/>
    &#34;&#34;&#34;<br/>
    ...<br/>

由路由器自动为此视图集自定义action方法形成的路由会是如下内容:

^books/latest/\(    name: book-latest<br/>
^books/{pk}/read/\)  name: book-read

路由router形成URL的方式

1) SimpleRouter

2)DefaultRouter

DefaultRouter与SimpleRouter的区别是,DefaultRouter会多附带一个默认的API根视图,返回一个包含所有列表视图的超链接响应数据。