drf 视图源码详解

mixin类和Generic类
- 导入
GenericAPIView 通用的apiview
- get_queryset(self):
generics 里面组合了mixins里面方法和GenericAPIView
ModelViewSet 多种请求映射
- 导入：
- 为什么可以可以做到请求映射？
自定义ViewSetMixin类

mixin类和Generic类

导入

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

from rest_framework.generics import GenericAPIView

CreateModelMixin 创建

源码路径为 rest_framework —> mixing.py —>CreateModelMixin

class CreateModelMixin(object):

    """

    Create a model instance.

    """

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

        # 传入前端传入的数据，进行反序列化

        serializer = self.get_serializer(data=request.data)

        # 判断是否全部都校验通过 通过了就执行下面语句

        # raise_exception=True 不通过直接报错，下面也不会执行

        serializer.is_valid(raise_exception=True)

        # 执行perform_create 实际就是.save() 保存

        self.perform_create(serializer)

        # 头部信息忽略

        headers = self.get_success_headers(serializer.data)

        # 遵循规范返回创建对象的数据

        # status 状态信息，对应的是一个个状态码

        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 {}

视图使用-post

class PublishView(CreateModelMixin,GenericAPIView):

  	queryset = models.Publish.objects.all()

  	# 内部执行的时候CreateModelMixin调用了serializer_class

    serializer_class = PublishSerializers

  		# 执行post请求就说明要添加数据

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

      # 执行create 自己没有就执行CreateModelMixin

      # 也就是上面的CreateModelMixin源码解析

        return self.create(request, *args, **kwargs)

ListModelMixin - 查看多条数据

源码路径为 rest_framework —> mixing.py —>ListModelMixin

class ListModelMixin(object):

    """

    List a queryset.

    """

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

        # 过滤相关

        # 这个时候调用了GenericAPIView内的get_queryset

        queryset = self.filter_queryset(self.get_queryset())

        # 分页相关

        page = self.paginate_queryset(queryset)

        # page不为空的情况下

        if page is not None:

            # 序列化多条

            serializer = self.get_serializer(page, many=True)

            # 返回序列化的数据

            return self.get_paginated_response(serializer.data)

        serializer = self.get_serializer(queryset, many=True)

        return Response(serializer.data)

视图-get-取所有数据

class PublishView(ListModelMixin,GenericAPIView):

  	queryset = models.Publish.objects.all()

    serializer_class = PublishSerializers

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

        return self.list(request, *args, **kwargs)

RetrieveModelMixin 获取单条数据

源码路径为 rest_framework —> mixing.py—>RetrieveModelMixin

class RetrieveModelMixin(object):

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

        # 获取单条

        instance = self.get_object()

        # 获取到序列化返回

        serializer = self.get_serializer(instance)

        return Response(serializer.data)

视图-get-取指定数据

class PublishDetailView(RetrieveModelMixin, UpdateModelMixin, DestroyModelMixin, GenericAPIView):

    queryset = models.Publish.objects.all()

    serializer_class = PublishSerializers

    # 获取指定一条

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

        return self.retrieve(request, *args, **kwargs)

UpdateModelMixin 更新单条数据

源码路径为 rest_framework —> mixing.py—>UpdateModelMixin

class UpdateModelMixin(object):

    """

    Update a model instance.

    """

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

        partial = kwargs.pop('partial', False)  

        # 要序列化单条数据

        instance = self.get_object()

        # 序列化

        serializer = self.get_serializer(instance, data=request.data, partial=partial)

        # 校验是否全部通过

        serializer.is_valid(raise_exception=True)

        # 直接保存

        self.perform_update(serializer)

        if getattr(instance, '_prefetched_objects_cache', None):

            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)

视图 - put- 更新指定数据

class PublishDetailView(RetrieveModelMixin, UpdateModelMixin, DestroyModelMixin, GenericAPIView):

    queryset = models.Publish.objects.all()

    serializer_class = PublishSerializers

    # 更新指定数据

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

        return self.update(request, *args, **kwargs)

DestroyModelMixin - 删除指定数据

class DestroyModelMixin(object):

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

        # 获取要删除的数据

        instance = self.get_object()

        # 直接执行删除

        self.perform_destroy(instance)

        # 返回信息

        return Response(status=status.HTTP_204_NO_CONTENT)

    def perform_destroy(self, instance):

        instance.delete()

视图 - delete- 删除指定数据

class PublishDetailView(RetrieveModelMixin, UpdateModelMixin, DestroyModelMixin, GenericAPIView):

    queryset = models.Publish.objects.all()

    serializer_class = PublishSerializers

    # 删除指定数据

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

        return self.destroy(request, *args, **kwargs)

GenericAPIView 通用的apiview

get_queryset(self):

def get_queryset(self):

    assert self.queryset is not None, (

        "'%s' should either include a `queryset` attribute, "

        "or override the `get_queryset()` method."

        % self.__class__.__name__

    )

    # 这个时候的queryset 是传递进来的queryset对象

    queryset = self.queryset

    # 判断是否是QuerySet，不是QuerySet 自动.all()

    # 说明queryset可以直接给它传递一个对象如 models.Publish.objects

    if isinstance(queryset, QuerySet):

        # Ensure queryset is re-evaluated on each request.

        queryset = queryset.all()

        # 返回queryset对象

    return queryset

generics 里面组合了mixins里面方法和GenericAPIView

导入

from rest_framework.generics import ListCreateAPIView,RetrieveUpdateDestroyAPIView

url

url(r'^publish/$', views.publishView.as_view()),

url(r'^publish/(?P<pk>\d+)/$', views.PublishDetailView.as_view())

ListCreateAPIView源码创建与查询多条

class ListCreateAPIView(mixins.ListModelMixin,

                        mixins.CreateModelMixin,

                        GenericAPIView):

  	# 获取多条

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

        return self.list(request, *args, **kwargs)

		# 创建数据

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

        return self.create(request, *args, **kwargs)

RetrieveUpdateDestroyAPIView源码查询单条更新删除

class RetrieveUpdateDestroyAPIView(mixins.RetrieveModelMixin,

                                   mixins.UpdateModelMixin,

                                   mixins.DestroyModelMixin,

                                   GenericAPIView):

		# 获取指定数据

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

        return self.retrieve(request, *args, **kwargs)

		# 更新全部

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

        return self.update(request, *args, **kwargs)

		# 局部更新

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

        return self.partial_update(request, *args, **kwargs)

		# 删除

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

        return self.destroy(request, *args, **kwargs)

视图

from rest_framework.generics import ListCreateAPIView,RetrieveUpdateDestroyAPIView

class publishView(ListCreateAPIView):

    queryset=models.Publish.objects.all()

    serializer_class=PublishSerializers

class PublishDetailView(RetrieveUpdateDestroyAPIView):

    queryset=models.Publish.objects.all()

    serializer_class=PublishSerializers

ModelViewSet 多种请求映射

导入：

from rest_framework.viewsets import ModelViewSet

路由：

    url(r'^publish/$', views.PublishView.as_view({'get':'list','post':'create'})),

    url(r'^publish/(?P<pk>\d+)/$', views.PublishView.as_view({'get':'retrieve','put':'update','delete':'destroy'})),

视图：

from rest_framework.viewsets import ModelViewSet

class PublishView(ModelViewSet):

    queryset=models.Publish.objects.all()

    serializer_class=PublishSerializers

# 这里面虽然可以满足方法的请求但是有时候我们会更具业务的需要，去修改，我们可以重写指定的方法，如create等

为什么可以可以做到请求映射？

主要是重写了as_view方法

1.ModelViewSet中唯一不通的就是继承了GenericViewSet,上面的方法中继承的是GenericAPIView 俩者不同

class ModelViewSet(mixins.CreateModelMixin,

                   mixins.RetrieveModelMixin,

                   mixins.UpdateModelMixin,

                   mixins.DestroyModelMixin,

                   mixins.ListModelMixin,

                   GenericViewSet):

    pass

2.GenericViewSet中pass??,继承了之前的GenericAPIView，但是多继承了一个ViewSetMixin

class GenericViewSet(ViewSetMixin, generics.GenericAPIView):

    pass

3.ViewSetMixin中仔细看as_view 和原生的Django.views.View.as_view的区别,多了一个参数

Django.views.View.as_view

def as_view(cls, **initkwargs):

  	pass

ViewSetMixin.as_view

def as_view(cls, actions=None, **initkwargs):

  	pass

4.所以路由中配置的字典{'get': 'list', 'post': 'create'}给了actions

 url(r'^publish/$', views.PublishView.as_view({'get': 'list', 'post': 'create'})),

 url(r'^publish/(?P<pk>\d+)/$',

        views.PublishView.as_view({'get': 'retrieve', 'put': 'update', 'delete': 'destroy'})),

5.ViewSetMixin.as_view 源码中如果可以看出如果继承了ViewSetMixin没有传递actions直接就会异常

if not actions:

    raise TypeError("The `actions` argument must be provided when "

                    "calling `.as_view()` on a ViewSet. For example "

                    "`.as_view({'get': 'list'})`")

6.ViewSetMixin.as_view核心代码,也就是这一段代码让我们的请求直接执行对应的执行函数

def view(request, *args, **kwargs):

    self = cls(**initkwargs)

    # 调用了传入的actions 赋值给了action_map

    self.action_map = actions

    # {'get': 'list', 'post': 'create'}

    # 解压赋值 请求给了method 处理参数给了action

    for method, action in actions.items():

        # self是自定义的那个路由函数的对象

        # 通过反射去对象中找action

        # handler就相当于 那个执行方法的内存地址

        handler = getattr(self, action)

        # 反射设置值 把执行方法的内存地址覆盖了请求，每次来请求执行的就是对于的执行函数

        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)

自定义ViewSetMixin类

相当于映射指定请求来了执行指定方法

from rest_framework.viewsets import ViewSetMixin

from rest_framework.views import APIView

# 要注意继承的顺序如果APIView继承在前按照mro列表先执行它里面的as_views,所以要放在前面

class Test(ViewSetMixin, APIView):

    def test(self, request, pk):

        print('自定义请求收到参数:', pk)

        return Response()

url

url(r'^test/(?P<pk>\d+)/$', views.Test.as_view({'get': 'test'})),