drf 视图源码详解

mixin类和Generic类
GenericAPIView 通用的apiview
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'})),