drf view component

Python之drf视图组件

一、Local verification Global verification source code analysis

截取一段views.py里的代码

def post(self, request):
    back_dic = {
    'code': 200, 'msg': '新增成功', 'result': ''}
    result = BookModelSerializer(data=request.data)
    if  not result.is_valid():
        return Response(result.errors)
    result.save()  # 保存数据
    back_dic['result'] = result.data
    return Response(back_dic)

Inside the serialized class object pointis_valid(),It is to verify the validity of the deserialized data

…………

二、Serialization component source code analysis

序列化组件,先调用__new__方法,如果many=True,生成ListSerializer对象,如果为False,生成Serializer对象
序列化对象.data方法--调用父类data方法---调用对象自己的to_representation（自定义的序列化类无此方法,去父类找）
Aerializer类里有to_representation方法,for循环执行attribute = field.get_attribute(instance)
再去Field类里去找get_attribute方法,self.source_attrs就是被切分的source,然后执行get_attribute方法,source_attrs
当参数传过去,判断是方法就加括号执行,是属性就把值取出来

三、请求与响应

1、Request

REST framework 传入视图的request对象不再是Django默认的HttpRequest对象,而是REST framework提供的扩展了HttpRequest类的Request类的对象.

REST framework 提供了Parser解析器,在接收到请求后会自动根据Content-Type指明的请求数据类型（如JSON、表单等）将请求数据进行parse解析,解析为类字典[QueryDict]对象保存到Request对象中.

Request对象的数据是自动根据前端发送数据的格式进行解析之后的结果

无论前端发送的哪种格式的数据,我们都可以以统一的方式读取数据.

1）.data

request.data 返回解析之后的请求体数据.类似于Django中标准的request.POST和 request.FILES属性,但提供如下特性：

• 包含了解析之后的文件和非文件数据
• 包含了对POST、PUT、PATCH请求方式解析后的数据
• 利用了REST framework的parsers解析器,不仅支持表单类型数据,也支持JSON数据

2）.query_params

request.query_params与Django标准的request.GET相同,只是更换了更正确的名称而已.

3）drfConfigure the request format

# 通过配置,Set the encoding format supported by the backend interface,Three are supported by default
# 1、可以在项目的settings.py配置文件中配置,Call it this“全局配置”
REST_FRAMEWORK = {
    
    'DEFAULT_PARSER_CLASSES': [
            'rest_framework.parsers.JSONParser',  # json
           	'rest_framework.parsers.FormParser',  # urlencoded
            'rest_framework.parsers.MultiPartParser'  # form-data文件格式
        ]
}

# 2、局部配置,Write class properties in the view class
from rest_framework.parsers import  JSONParser,FormParser,MultiPartParser
parser_classes = [JSONParser,] # Local configuration defaults to this method only acceptedjson格式数据

2、Response

from rest_framework.response import Response

Response(data, status=None, template_name=None, headers=None, content_type=None)

1）返回数据

data数据不要是render处理之后的数据,只需传递python的内建类型数据即可,REST framework会使用renderer渲染器处理data.

data不能是复杂结构的数据,如Django的模型类对象,对于这样的数据我们可以使用Serializer序列化器序列化处理后（转为了Python字典类型）再传递给data参数.

参数说明：

• data: 为响应准备的序列化处理后的数据;
• status: 状态码,默认200;
• template_name: 模板名称,如果使用HTMLRenderer 时需指明;
• headers: 用于存放响应头信息的字典;
• content_type: 响应数据的Content-Type,通常此参数无需传递,REST framework会根据前端所需类型数据来设置该参数.

Status codes can be written with numbers,can also be importedstatus包,Write a constant for the status code

from rest_framework import status

# 如下使用
return Response(back_dic,status=status.HTTP_200_OK)
return Response(back_dic,status=status.HTTP_404_NOT_FOUND)

2）drf配置响应格式

REST framework提供了一个响应类Response,使用该类构造响应对象时,响应的具体数据内容会被转换（render渲染）成符合前端需求的类型.

REST framework提供了Renderer 渲染器,用来根据请求头中的Accept（接收数据类型声明）来自动转换响应数据到对应格式.如果前端请求中未进行Accept声明,则会采用默认方式处理响应数据,我们可以通过配置来修改默认响应格式.

可以在rest_framework.settings查找所有的drf默认配置项

# 全局配置
REST_FRAMEWORK = {
    
    'DEFAULT_RENDERER_CLASSES': [ # 默认响应渲染类
        'rest_framework.renderers.JSONRenderer',  # json渲染器
        'rest_framework.renderers.BrowsableAPIRenderer',  # 浏览API渲染器
    ]  
}

3）自己封装Response对象

1、In the future, I will use my own custom packageresponse
class APIResponse(Response):
    def __init__(self, code=100, msg='成功', data=None, status=None, headers=None, content_type=None, **kwargs):
        dic = {
    'code': code, 'msg': msg}
        if data:
            dic['data'] = data

        dic.update(kwargs) # 这里使用update
        super(APIResponse,self).__init__(data=dic, status=status,
                         template_name=None, headers=headers,
                         exception=False, content_type=content_type)

2、使用
 return APIResponse(code=100,msg='查询成功',data=ser.data,count=200,next='http://xxx.com')

四、两个视图基类

1、APIView

from rest_framework.views import APIView

APIView是REST framework提供的所有视图的基类,继承自Django的View父类.

APIView与View的不同之处在于：

• 传入到视图方法中的是REST framework的Request对象,而不是Django的HttpRequeset对象;
• 视图方法可以返回REST framework的Response对象,视图会为响应数据设置（render）符合前端要求的格式;
• 任何APIException异常都会被捕获到,并且处理成合适的响应信息;
• 在进行dispatch()分发前,会对请求进行身份认证、权限检查、流量控制.

在APIView中仍以常规的类视图定义方法来实现get() 、post() 或者其他请求方式的方法.

class publish(APIView):
    # 获取所有出版社接口
    def get(self,request):
        back_dic = {
    'code':200,'msg':'查询成功','result':''}
        res = models.Publish.objects.all()
        result = PublishModelSerializer(instance=res,many=True)
        back_dic['result'] = result.data
        return Response(back_dic)

2、GenericAPIView[通用视图类]

from rest_framework.generics import GenericAPIView

继承自APIVIew,主要增加了操作序列化器和数据库查询的方法,作用是为下面Mixin扩展类的执行提供方法支持.通常在使用时,可搭配一个或多个Mixin扩展类.

''' There are two class properties queryset = Book.objects.all() # The data you want to serialize serializer_class = serializer.BookSerializer # The serialization class you want to use 三个方法 get_queryset() # 获取要序列化的数据 get_serializer() # Get the serialization class to use get_object() # 获取单条数据（一定要用pk,如果你想改,重写类属性lookup_field） '''

# 使用GenericAPIView 通用视图类
from rest_framework.generics import GenericAPIView

 # 书籍 无参
class Book(GenericAPIView):
    queryset = models.Book.objects.all()   # 获取所有数据的queryset对象
    serializer_class = BookModelSerializer  # Get the serialized class to be used
    # 获取所有图书接口
    def get(self, request):
        back_dic = {
    'code': 200, 'msg': '查询成功', 'result': ''}
        res = self.get_queryset() # 获取所有数据
        result = self.get_serializer(instance=res, many=True)  # 使用BookModelSerializer序列化类

        back_dic['result'] = result.data
        return Response(back_dic)

    def post(self, request):
        back_dic = {
    'code': 200, 'msg': '新增成功', 'result': ''}
        result = self.get_serializer(data=request.data)

        if  not result.is_valid():
            return Response(result.errors)

        result.save()  # 保存数据
        back_dic['result'] = result.data
        return Response(back_dic)


class Book_param(GenericAPIView):
    queryset = models.Book.objects.all()  # 获取所有数据的queryset对象
    serializer_class = BookModelSerializer  # Get the serialized class to be used
    def get(self,request,**kwargs):
        back_dic = {
    'code': 200, 'msg': '查询成功', 'result': ''}
        res = self.get_object() # 获取单条数据
        result = self.get_serializer(instance=res)

        back_dic['result'] = result.data
        return Response(back_dic)

    def delete(self,request,**kwargs):
        back_dic = {
    'code': 200, 'msg': '删除成功'}
        models.Book.objects.filter(**kwargs).delete()
        return Response(back_dic)

    def put(self,request,**kwargs):
        back_dic = {
    'code': 200, 'msg': '修改成功', 'result': ''}
        res = self.get_object()
        result = self.get_serializer(instance=res,data=request.data)

        if  result.is_valid() ==False:
            return Response(result.errors)

        result.save()
        back_dic['result'] = result.data
        return Response(back_dic)

五、五个视图扩展类

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.

1、ListModelMixin

列表视图扩展类,提供list(request, *args, **kwargs)方法快速实现列表视图,返回200状态码.

该Mixin的list方法会对数据进行过滤和分页.

This method is to get all objects

源码：

class ListModelMixin:
    """ List a queryset. """
    def list(self, request, *args, **kwargs):
        # 过滤
        queryset = self.filter_queryset(self.get_queryset())
		# 分页
        page = self.paginate_queryset(queryset)
        if page is not None:
            serializer = self.get_serializer(page, many=True)
            return self.get_paginated_response(serializer.data)
		# 序列化
        serializer = self.get_serializer(queryset, many=True)
        return Response(serializer.data)

2、CreateModelMixin

创建视图扩展类,提供create(request, *args, **kwargs)方法快速实现创建资源的视图,成功返回201状态码.

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:
    """ Create a model instance. """
    def create(self, request, *args, **kwargs):
        # 获取序列化qi
        serializer = self.get_serializer(data=request.data)
        # 数据校验
        serializer.is_valid(raise_exception=True)
        # 调用perform_create方法保存,Other requirements can be rewritten laterperform_create方法
        self.perform_create(serializer)
        headers = self.get_success_headers(serializer.data)
        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:
            return {
    'Location': str(data[api_settings.URL_FIELD_NAME])}
        except (TypeError, KeyError):
            return {
    }

3、RetrieveModelMixin

详情视图扩展类,提供retrieve(request, *args, **kwargs)方法,可以快速实现返回一个存在的数据对象.

如果存在,返回200, 否则返回404.

源代码：

class RetrieveModelMixin:
    """ Retrieve a model instance. """
    def retrieve(self, request, *args, **kwargs):
        # 获取单个对象,会检查对象的权限
        instance = self.get_object()
        # 序列化
        serializer = self.get_serializer(instance)
        return Response(serializer.data)

4、UpdateModelMixin

UPDATE Tried to extend the class,提供update(self, request, *args, **kwargs)方法,可以快速实现更新一个存在的数据对象

同时也提供partial_update(request, *args, **kwargs)方法,可以实现局部更新.

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:
    """ Update a model instance. """
    def update(self, request, *args, **kwargs):
        partial = kwargs.pop('partial', False)
        # 获取单个对象,会检查对象的权限
        instance = self.get_object()
        # 序列化
        serializer = self.get_serializer(instance, data=request.data, partial=partial)
        # 校验数据
        serializer.is_valid(raise_exception=True)
        # 调用perform_update方法保存数据,It can be rewritten later according to business needsperform_update方法
        self.perform_update(serializer)

        if getattr(instance, '_prefetched_objects_cache', None):
            # If 'prefetch_related' has been applied to a queryset, we need to
            # forcibly invalidate the prefetch cache on the instance.
            instance._prefetched_objects_cache = {
    }

        return Response(serializer.data)

    def perform_update(self, serializer):
        serializer.save()

    def partial_update(self, request, *args, **kwargs):
        kwargs['partial'] = True
        return self.update(request, *args, **kwargs)

5、DestroyModelMixin

删除视图扩展类,提供destroy(request, *args, **kwargs)方法,可以快速实现删除一个存在的数据对象.

成功返回204,不存在返回404.

源代码：

class DestroyModelMixin:
    """ Destroy a model instance. """
    def destroy(self, request, *args, **kwargs):
        # 获取单个对象,会检查对象的权限
        instance = self.get_object()
         # 调用perform_destroy方法删除数据,It can be rewritten later according to business needsperform_update方法
        self.perform_destroy(instance)
        # 返回状态码
        return Response(status=status.HTTP_204_NO_CONTENT)

    def perform_destroy(self, instance):
        instance.delete()

6、综合

# 使用GenericAPIView 通用视图类
from rest_framework.generics import GenericAPIView
# Use five attempts to extend the class
from rest_framework.mixins import ListModelMixin,CreateModelMixin,RetrieveModelMixin,UpdateModelMixin,DestroyModelMixin

 # 书籍 无参
class Book(GenericAPIView,ListModelMixin,CreateModelMixin):
    queryset = models.Book.objects.all()   # 获取所有数据的queryset对象
    serializer_class = BookModelSerializer  # Get the serialized class to be used
    # 获取所有图书接口
    def get(self, request):
        # back_dic = {'code': 200, 'msg': '查询成功', 'result': ''}
        # res = self.get_queryset() # 获取所有数据
        # result = self.get_serializer(instance=res, many=True) # 使用BookModelSerializer序列化类
        #
        # back_dic['result'] = result.data
        return self.list(request)

    def post(self, request):
        return self.create(request)


class Book_param(GenericAPIView,RetrieveModelMixin,UpdateModelMixin,DestroyModelMixin):
    queryset = models.Book.objects.all()  # 获取所有数据的queryset对象
    serializer_class = BookModelSerializer  # Get the serialized class to be used
    def get(self,request,**kwargs):
        return self.retrieve(self,request,**kwargs)

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

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

六、GenericAPIView九个视图子类

1、ListAPIView

提供get方法（获取所有）

继承自：GenericAPIView,ListModelMixin

2、CreateAPIView

提供post方法

继承自：GenericAPIView,CreateModelMixin

3、RetrieveAPIView

提供get方法（获取单个）

继承自：GenericAPIView,RetrieveModelMixin

4、UpdateAPIView

提供update方法

继承自：GenericAPIView,UpdateModelMixin

5、DestroyAPIView

提供delete方法

继承自：GenericAPIView,DestroyModelMixin

6、ListCreateAPIView

提供get,put,patch方法

继承自：GenericAPIView,ListModelMixin,RetrieveModelMixin

7、RetrieveDestroyAPIView

提供get,delete方法

继承自：GenericAPIView,DestroyModelMixin

8、RetrieveUpdateAPIView

提供get,put,patch方法

继承自：GenericAPIView,RetrieveModelMixin,UpdateModelMixin

9、 RetrieveUpdateDestoryAPIView

提供get,put,patch,delete方法

继承自：GenericAPIView,RetrieveModelMixin,UpdateModelMixin,DestroyModelMixin

10、总结

# 使用GenericAPIView 通用视图类
# from rest_framework.generics import GenericAPIView
# Extend the class with nine views
from rest_framework.generics import ListAPIView,CreateAPIView,RetrieveAPIView,UpdateAPIView,DestroyAPIView,ListCreateAPIView,RetrieveUpdateAPIView,RetrieveUpdateDestroyAPIView


 # 书籍 无参
class Book(ListCreateAPIView):
    queryset = models.Book.objects.all()   # 获取所有数据的queryset对象
    serializer_class = BookModelSerializer  # Get the serialized class to be used



class Book_param(RetrieveUpdateDestroyAPIView):
    queryset = models.Book.objects.all()  # 获取所有数据的queryset对象
    serializer_class = BookModelSerializer  # Get the serialized class to be used

七、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()
        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 = [
    path('books/', BookInfoViewSet.as_view({
    'get':'list'}),
    path('books/<int:pk>', BookInfoViewSet.as_view({
    'get': 'retrieve'})
]

1、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、GenericAPIView

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.

from rest_framework.viewsets import GenericViewSet
from rest_framework.mixins import ListModelMixin,CreateModelMixin,RetrieveModelMixin,UpdateModelMixin,DestroyModelMixin
class Student4ViewSet(GenericViewSet,ListModelMixin,CreateModelMixin,RetrieveModelMixin,UpdateModelMixin,DestroyModelMixin):
    queryset = Student.objects.all()
    serializer_class = StudentModelSerializer

url的定义

urlpatterns = [
    path("students7/", views.Student4ViewSet.as_view({
    "get": "list", "post": "create"})),
    re_path("students7/(?P<pk>\d+)/", views.Student4ViewSet.as_view({
    "get": "retrieve","put":"update","delete":"destroy"})),

]

3、ModelViewSet

继承自GenericViewSet,同时包括了ListModelMixin、RetrieveModelMixin、CreateModelMixin、UpdateModelMixin、DestoryModelMixin.（五个视图扩展类）

4、ReadOnlyModelViewSet

继承自GenericViewSet,同时包括了ListModelMixin、RetrieveModelMixin.

2、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.

from rest_framework.viewsets import ModelViewSet,ReadOnlyModelViewSet
class StudentModelViewSet(ModelViewSet):
    queryset = Student.objects.all()
    serializer_class = StudentModelSerializer

    def login(self,request):
        """学生登录功能"""
        return Response({
    "message":"登录成功"})

url的定义

urlpatterns = [
    path("students8/", views.StudentModelViewSet.as_view({
    "get": "list", "post": "create"})),
    re_path("students8/(?P<pk>\d+)/",
            views.StudentModelViewSet.as_view({
    "get": "retrieve", "put": "update", "delete": "destroy"})),

    path("stu/login/",views.StudentModelViewSet.as_view({
    "get":"login"})) # 自定义action动作

]

八、总结

#两个基类
APIView
GenericAPIView：有关数据库操作
类属性：queryset 和serializer_class
方法：self.get_queryset(),self.get_serializer()和self.get_object()

#5个视图扩展类(rest_framework.mixins)
CreateModelMixin：create方法创建一条
DestroyModelMixin：destory方法删除一条
ListModelMixin：list方法获取所有
RetrieveModelMixin：retrieve获取一条
UpdateModelMixin：update修改一条

#9个子类视图(rest_framework.generics)
CreateAPIView:继承CreateModelMixin,GenericAPIView,有post方法,新增数据
DestroyAPIView：继承DestroyModelMixin,GenericAPIView,有delete方法,删除数据
ListAPIView：继承ListModelMixin,GenericAPIView,有get方法获取所有
UpdateAPIView：继承UpdateModelMixin,GenericAPIView,有put和patch方法,修改数据
RetrieveAPIView：继承RetrieveModelMixin,GenericAPIView,有get方法,获取一条


ListCreateAPIView：继承ListModelMixin,CreateModelMixin,GenericAPIView,有get获取所有,post方法新增
RetrieveDestroyAPIView：继承RetrieveModelMixin,DestroyModelMixin,GenericAPIView,有get方法获取一条,delete方法删除
RetrieveUpdateAPIView：继承RetrieveModelMixin,UpdateModelMixin,GenericAPIView,有get获取一条,put,patch修改
RetrieveUpdateDestroyAPIView：继承RetrieveModelMixin,UpdateModelMixin,DestroyModelMixin,GenericAPIView,有get获取一条,put,patch修改,delete删除

#视图集
ViewSetMixin：重写了as_view 
ViewSet：     继承ViewSetMixin和APIView

GenericViewSet：继承ViewSetMixin, generics.GenericAPIView
ModelViewSet：继承mixins.CreateModelMixin,mixins.RetrieveModelMixin,mixins.UpdateModelMixin,mixins.DestroyModelMixin,mixins.ListModelMixin,GenericViewSet
ReadOnlyModelViewSet：继承mixins.RetrieveModelMixin,mixins.ListModelMixin,GenericViewSet