DRF-(4)

内容概览

• DRF之请求与响应
• DRF之视图组件
• DRF之视图集

DRF之请求与响应

Request和Response类

• Request类
  继承APIView后，传入视图的request对象就不再是Django默认的HttpResponse对象了；而是drf扩展扩展之后的Request类的对象
  使用request.data可以获取POST、PUT、PATCH等传入的数据；在原来的request中，put提交的数据在POST中无法获取
  使用request.query_params获取GET请求携带的数据
  其余方法与原来的request使用方法一致，底层原理是使用了__getattr__返回原来request中的方法
  
• Response类

"""Response中有多个参数"""
data=None  # 字典,列表;序列化成json格式字符串,返回给前端
status=None  # http响应的状态码,默认是200;导入rest_framework.status修改
headers=None  # http响应头,可以以字典的形式往里边添加数据
"""django想要在响应头中添加数据要先获取JsonResponse对象再添加
res=JsonResponse()
res['xxx']='yyy'
return res"""
template_name=None  # 指定的模板,可以在浏览器中看到喊看的页面
content_type=None  # 响应的编码格式

drf能够解析的请求编码与响应编码

• 请求编码

"""默认能够解析"""
urlencoded、form-data、json

"""通过drf内置的配置文件,默认配置好了可以解析的请求编码,所以没有在配置文件(settings.py)中配置也可以使用
在drf的配置文件中,使用的DEFAULT_PARSER_CLASSES(默认的解析类)"""
'rest_framework.parsers.JSONParser',  # 可以解析json格式
'rest_framework.parsers.FormParser',  # 可以解析urlencoded格式
'rest_framework.parsers.MultiPartParser'  # 可以解析form-data格式


"""如果想要让接口只能接收指定格式,有两种修改方式"""
1. 全局配置:修改项目配置文件,指定项目中所有接口都遵循这个配置
	settings.py:
	REST_FRAMEWORK = {
				'DEFAULT_PARSER_CLASSES': [
					'rest_framework.parsers.JSONParser',
					# 'rest_framework.parsers.FormParser',
					# 'rest_framework.parsers.MultiPartParser',
                ],
            }
2. 局部配置:在视图类中配置
	class PublishView(APIView):
	    parser_classes = ['JSONParser', 'FormParser', 'MultiParParser']

"""解析类的使用顺序:优先使用视图类中的,其次是项目配置文件中的(settings.py),最后是内置的配置"""

• 响应编码

"""默认情况下,响应的编码是根据客户端类型决定的"""
全局配置:
REST_FRAMEWORK = {
		'DEFAULT_RENDERER_CLASSES': [
			# 'rest_framework.renderers.JSONRenderer', # json格式
			'rest_framework.renderers.BrowsableAPIRenderer', #浏览器的格式
        ]
    }

局部配置
class TestView(APIView):
	renderer_classes = [JSONRenderer,]

"""实际编码中,响应编码一般不用配置,使用默认即可"""

DRF之视图组件

drf提供了一个顶层的视图类APIView，我们可以通过继承APIView写视图类
后期要写的代码可能重复代码比较多，就可以使用到面向对象的继承与封装

两个视图基类

1. APIView
   是drf提供的所有视图的基类，继承自Django的View
2. GenericAPIView
   继承自APIView，主要增加了操作序列化和数据查询的方法

   类属性:
   	queryset = User.objects.all()  # queryset对象
   	serializer_class = Userserializer  # serializer类
   	"""了解"""
   	lookup_field  # get_object通过该属性的值,获取单个对象查询的值,默认为pk
   	filter_backends  # 过滤类
   	pagination_class  # 分页类
   方法:
   	self.get_queryset()  # 获取所有要序列化的数据
   	self.get_serializer_class()  # 获取所有要使用的序列化类
   	self.get_serializer  # 获取序列化类,需要加括号调用
   	self.get_object()  # 根据pk获取单个数据
   	"""了解"""
   	filter_queryset  # 过滤相关
   	paginate_xxx  # 分页相关
   

基于APIView写5个接口

class BookView(APIView):
    def get(self, request):
        book_obj = models.Book.objects.all()
        res = BookModelSerializer(instance=book_obj, many=True)
        return Response(res.data)

    def post(self, request):
        res = BookModelSerializer(data=request.data)
        if res.is_valid():
            res.save()
            return Response({'code': 100, 'msg': res.data})
        else:
            return Response({'code': 101, 'msg': res.errors})


class BookDetailView(APIView):
    def get(self, request, pk):
        book_obj = models.Book.objects.filter(pk=pk).first()
        res = BookModelSerializer(instance=book_obj)
        return Response(res.data)

    def put(self, request, pk):
        book_obj = models.Book.objects.filter(pk=pk).first()
        res = BookModelSerializer(instance=book_obj, data=request.data)
        if res.is_valid():
            res.save()
            return Response({'code': 100, 'msg': res.data})
        else:
            return Response({'code': 101, 'msg': res.errors})

    def delete(self, request, pk):
        models.Book.objects.filter(pk=pk).delete()
        return Response()

基于GenericAPIView写5个接口

class BookView(GenericAPIView):
    queryset = models.Book.objects.all()
    serializer_class = BookModelSerializer

    def get(self, request):
        book_obj = self.get_queryset()
        res = self.get_serializer(instance=book_obj, many=True)
        return Response(res.data)

    def post(self, request):
        res = self.get_serializer(data=request.data)
        if res.is_valid():
            res.save()
            return Response({'code': 100, 'msg': res.data})
        else:
            return Response({'code': 101, 'msg': res.errors})


class BookDetailView(GenericAPIView):
    queryset = models.Book.objects.all()
    serializer_class = BookModelSerializer

    def get(self, request, pk):
        book_obj = self.get_object()
        res = self.get_serializer(instance=book_obj)
        return Response(res.data)

    def put(self, request, pk):
        book_obj = self.get_object()
        res = self.get_serializer(instance=book_obj, data=request.data)
        if res.is_valid():
            res.save()
            return Response({'code': 100, 'msg': res.data})
        else:
            return Response({'code': 101, 'msg': res.errors})

    def delete(self, request, pk):
        self.get_queryset().filter(pk=pk).delete()
        return Response()

练习

"""使用面向对象，写5个父类， 继承GenericAPIView+某几个父类后，就有某几个接口"""
class ListModelMixin():
    def get(self, request):
        book_obj = self.get_queryset()
        res = self.get_serializer(instance=book_obj, many=True)
        return Response(res.data)


class CreateModelMixin():
    def post(self, request):
        res = self.get_serializer(data=request.data)
        if res.is_valid():
            res.save()
            return Response({'code': 100, 'msg': res.data})
        else:
            return Response({'code': 101, 'msg': res.errors})


class RetrieveModelMixin():
    def get(self, request, pk):
        book_obj = self.get_object()
        res = self.get_serializer(instance=book_obj)
        return Response(res.data)


class UpdateModelMixin():
    def put(self, request, pk):
        book_obj = self.get_object()
        res = self.get_serializer(instance=book_obj, data=request.data)
        if res.is_valid():
            res.save()
            return Response({'code': 100, 'msg': res.data})
        else:
            return Response({'code': 101, 'msg': res.errors})


class DestroyModelMixin():
    def delete(self, request, pk):
        self.get_queryset().filter(pk=pk).delete()
        return Response()


class BookView(GenericAPIView, ListModelMixin, CreateModelMixin):
    queryset = models.Book.objects.all()
    serializer_class = BookModelSerializer


class BookDetailView(GenericAPIView, RetrieveModelMixin, UpdateModelMixin, DestroyModelMixin):
    queryset = models.Book.objects.all()
    serializer_class = BookModelSerializer

"""9个视图子类"""

class CreateAPIView(GenericAPIView, CreateModelMixin):
    pass


class ListAPIView(GenericAPIView, ListModelMixin):
    pass


class RetrieveAPIView(GenericAPIView, RetrieveModelMixin):
    pass


class DestroyAPIView(GenericAPIView, DestroyModelMixin):
    pass


class UpdateAPIView(GenericAPIView, UpdateModelMixin):
    pass


class RetrieveUpdateAPIView(GenericAPIView, RetrieveModelMixin, UpdateModelMixin):
    pass


class UpdateDestroyAPIView(GenericAPIView, UpdateModelMixin, DestroyModelMixin):
    pass


class RetrieveDestroyAPIView(GenericAPIView, RetrieveModelMixin, DestroyModelMixin):
    pass


class RetrieveUpdateDestroyAPIView(GenericAPIView, RetrieveModelMixin, UpdateModelMixin, DestroyModelMixin):
    pass

class BookView(ListAPIView, CreateAPIView):
    queryset = models.Book.objects.all()
    serializer_class = BookModelSerializer


class BookDetailView(RetrieveUpdateDestroyAPIView):
    queryset = models.Book.objects.all()
    serializer_class = BookModelSerializer

5个视图扩展类

• 基于GenericAPIView+5个视图扩展类写接口

from rest_framework.mixins import ListModelMixin, CreateModelMixin, RetrieveModelMixin, UpdateModelMixin, DestroyModelMixin

class BookView(GenericAPIView, ListModelMixin, CreateModelMixin):
    queryset = models.Book.objects.all()
    serializer_class = BookModelSerializer

    def get(self, request, *args, **kwargs):
        return self.list(request, *args, **kwargs)

    def post(self, request, *args, **kwargs):
        return self.create(request, *args, **kwargs)


class BookDetailView(GenericAPIView, RetrieveModelMixin, UpdateModelMixin, DestroyModelMixin):
    queryset = models.Book.objects.all()
    serializer_class = BookModelSerializer

    def get(self, request, *args, **kwargs):
        return self.retrieve(request, *args, **kwargs)

    def put(self, request, *args, **kwargs):
        return self.update(request, *args, **kwargs)

    def delete(self, request, *args, **kwargs):
        return self.destroy(request, *args, **kwargs)

"""
必须配合GenericAPIView使用,不能配合APIView使用(使用到了GenericAPIView中的方法)
RetrieveModelMixin:写了一个Create方法，就是原来post中的代码
RetrieveModelMixin：retrieve，就是原来的get
UpdateModelMixin：update方法，就是原来的put
ListModelMixin：list方法，就是原来的get
DestroyModelMixin：destroy方法，就是原来的delete
"""

9个视图子类

• 基于9个视图子类写接口

from rest_framework.generics import ListAPIView, CreateAPIView, ListCreateAPIView, RetrieveAPIView, UpdateAPIView, DestroyAPIView, RetrieveUpdateAPIView, RetrieveDestroyAPIView, RetrieveUpdateDestroyAPIView


class BookView(ListCreateAPIView):
    queryset = models.Book.objects.all()
    serializer_class = BookModelSerializer


class BookDetailView(RetrieveUpdateDestroyAPIView):
    queryset = models.Book.objects.all()
    serializer_class = BookModelSerializer

"""
class ListAPIView(mixins.ListModelMixin,
                  GenericAPIView):
    def get(self, request, *args, **kwargs):
        return self.list(request, *args, **kwargs)
将重复的代码再次帮我们封装了,需要哪一些接口直接继承一个类即可
注意没有Retrieve与Destroy结合的类
"""

视图集

继承ModelViewSet编写5个接口

from rest_framework.viewsets import ModelViewSet, ReadOnlyModelViewSet  
# ModelViewSet有五个接口
# ReadOnlyModelViewSet之有create与retrieve接口,使用路由也需要修改
"""只需要写一个视图类即可"""
class BookView(ModelViewSet):
    queryset = models.Book.objects.all()
    serializer_class = BookModelSerializer

"""需要修改路由"""
    path('books/', views.BookView.as_view({'get': 'list', 'post': 'create'})),
    path('books//', views.BookDetailView.as_view({'get': 'retrieve', 'put': 'update', 'delete': 'destroy'})),

源码分析ViewSetMixin

@classonlymethod
def as_view(cls, actions=None, **initkwargs):
    # 路由中as_view中必须传参数，必须传字典：{'get': 'list', 'post': 'create'}
    if not actions: 
        raise TypeError("The `actions` argument must be provided when "
                        "calling `.as_view()` on a ViewSet. For example "
                        "`.as_view({'get': 'list'})`")
	# 路由匹配成功，执行view(request)，request是老的request
    def view(request, *args, **kwargs):
	    # actions={'get': 'list', 'post': 'create'}
        for method, action in actions.items():
            # method:get      action:list
            # self 是视图类的对象中通过反射，查找list，
            # handler视图类中的list方法
            handler = getattr(self, action)
            # 向视图类的对象中，反射 method:get,handler:list方法
            # self.get=list
            setattr(self, method, handler)
        return self.dispatch(request, *args, **kwargs)
    return csrf_exempt(view)


# 只要继承了ViewSetMixin，以后路由写法变量，都要协程：views.UserView.as_view({'get': 'list', 'post': 'create'}))
# 这样写好以后，对应的请求方式来了，就会执行配置的方法


# 扩展：
	-以后只要继承了ViewSetMixin，视图类中可以写任意名字的方法，不用非得写get，post，delete

"""总结
APIView：as_view,dispatch
GenericAPIView：继承APIView,有queryset/serializer_class类属性
	get_object/get_queryset/get_serializer方法
5个视图扩展类：ListModelMixin/CreateModelMixin/RetrieveModelMixin/UpdateModelMixin/DestroyModelMixin,需要配合GenericAPIVIew使用
9个视图子类：5个视图扩展类与GenericAPIView的组合
视图集：
	ViewSetMixin：重写了as_view，继承时需要注意查找顺序，先继承该类
	ViewSet：继承了ViewSetMixin与APIView
	GenericAPIViewSet：继承了ViewSetMixin与GenericAPIView
	ModelViewSet：继承了5个视图扩展类与GenericAPIViewSet
	ReadOnlyModelViewSet：继承了2个视图扩展类与GenericAPIViewSet
"""

练习

• 视图中所有类：继承关系画出来，有哪些常用属性或方法写出来