视图家族之视图工具集viewsets
一、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，而是通过重写as_view函数进行映射实现动作 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：
# 视图工具集
from rest_framework import viewsets
class BookInfoViewSet(viewsets.ViewSet):
def list(self, request):
books = BookInfo.objects.all()
serializer = BookInfoSerializer(books, many=True)
return Response(serializer.data)
def retrieve(self, request, pk=None):
try:
books = BookInfo.objects.get(id=pk)
except BookInfo.DoesNotExist:
return Response(status=status.HTTP_404_NOT_FOUND)
serializer = BookInfoSerializer(books)
return Response(serializer.data)
在设置路由时，我们可以如下操作
urlpatterns = [
url(r'^books/$', BookInfoViewSet.as_view({'get':'list'}),
url(r'^books/(?P<pk>d+)/$', BookInfoViewSet.as_view({'get': 'retrieve'})
]
常用视图集父类
1） ViewSet
继承自APIView与ViewSetMixin，作用也与APIView基本类似，提供了身份认证、权限校验、流量管理等。
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
使用ViewSet通常并不方便，因为list、retrieve、create、update、destory等方法都需要自己编写，而这些方法与前面讲过的Mixin扩展类提供的方法同名，所以我们可以通过继承Mixin扩展类来复用这些方法而无需自己编写。但是Mixin扩展类依赖与GenericAPIView，所以还需要继承GenericAPIView。
GenericViewSet就帮助我们完成了这样的继承工作，继承自GenericAPIView与ViewSetMixin，在实现了调用as_view()时传入字典（如{'get':'list'}）的映射处理工作的同时，还提供了GenericAPIView提供的基础方法，可以直接搭配Mixin扩展类使用。
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()
serializer_class = BookInfoSerializer
url的定义
urlpatterns = [
url(r'^books/$', views.BookInfoViewSet.as_view({'get': 'list'})),
url(r'^books/(?P<pk>d+)/$', views.BookInfoViewSet.as_view({'get': 'retrieve'})),
]
3）ModelViewSet
继承自GenericViewSet，同时包括了ListModelMixin、RetrieveModelMixin、CreateModelMixin、UpdateModelMixin、DestoryModelMixin。
4）ReadOnlyModelViewSet
继承自GenericViewSet，同时包括了ListModelMixin、RetrieveModelMixin。
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()
serializer_class = BookInfoSerializer
def latest(self, request):
"""
返回最新的图书信息
"""
book = BookInfo.objects.latest('id')
serializer = self.get_serializer(book)
return Response(serializer.data)
def read(self, request, pk):
"""
修改图书的阅读量数据
"""
book = self.get_object()
book.bread = request.data.get('read')
book.save()
serializer = self.get_serializer(book)
return Response(serializer.data)
url的定义
urlpatterns = [
url(r'^books/$', views.BookInfoViewSet.as_view({'get': 'list'})),
url(r'^books/latest/$', views.BookInfoViewSet.as_view({'get': 'latest'})),
url(r'^books/(?P<pk>d+)/$', views.BookInfoViewSet.as_view({'get': 'retrieve'})),
url(r'^books/(?P<pk>d+)/read/$', views.BookInfoViewSet.as_view({'put': 'read'})),
]
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()
serializer_class = BookInfoModelSerializer
def get_top_5(self,request):
"""获取评论值最多的5条数据"""
# 操作数据库
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
二、总结
- 重写as_views（）方法通过反射机制实现对应功能的请求，as_views()完成了请求自定义映射，将所有请求方式与响应方法名，通过映射关系交给用户自己配置
- GenericViewSet类作为ReadOnlyModelViewSet的父类类作为ReadOnlyModelViewSet的父类，解决了单查和群查共存，实现继承工具类中的单查和群查的方法
- ViewSet和GenericViewSet类的区别：登录接口post不需要增
- 所以GenericViewSet标准的资源接口post请求一定会往数据库中增，ViewSet他是非资源接口post不需要数据库增数据的交互
- 可以实现自定义请求的方法
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 name and description initkwargs may be explicitly overridden for
# certain route configurations. eg, names of extra actions.
cls.name = None
cls.description = None
# The suffix initkwarg is reserved for displaying the viewset type.
# This initkwarg should have no effect if the name is provided.
# eg. 'List' or 'Instance'.
cls.suffix = None
# The detail initkwarg is reserved for introspecting the viewset type.
cls.detail = 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))
# name and suffix are mutually exclusive
if 'name' in initkwargs and 'suffix' in initkwargs:
raise TypeError("%s() received both `name` and `suffix`, which are "
"mutually exclusive arguments." % (cls.__name__))
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
# 设置具体执行函数响应
for method, action in actions.items():
handler = getattr(self, action)
setattr(self, method, handler)
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=())
update_wrapper(view, cls.dispatch, assigned=())
view.cls = cls
view.initkwargs = initkwargs
view.actions = actions
return csrf_exempt(view)