drf 源码分析之 ModelViewSet五层演进之路(含详细图解)

博主： Michael
发布时间：2020 年 10 月 14 日
560次浏览
10028字数
分类： python Django

## 先总结:

drf的核心是ModelViewSet类的演变, 所以懂了它基本上drf就可以毕业了

1. APIView (继承Django的View)
   * 去除csrf, 数据放到.data中, 执行三大认证
     🆑🆑🆑🆑第二层🆑🆑🆑🆑
2. GenericAPIView(继承APIView)
   * 封装orm的instance 与 serializer 到属性中, 以方法形式供调用
     🆑🆑🆑🆑第三层🆑🆑🆑🆑
3. 引入 xxxModelMixin
   * 封装*每个执行过程* 到list/create/update/retrieve/destroy方法属性中
     * ListModelMixin
     * CreateModelMixin
     * UpdateModelMixin
     * RetrieveModelMixin
     * DestroyModelMixin

```python
# 直接执行对应方法即可
class BooksGenericAPIView(GenericAPIView,
                          ListModelMixin,
                          CreateModelMixin,):
    queryset = models.Book.objects
    serializer_class = serializers.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)
```

🆑🆑🆑🆑第四层🆑🆑🆑🆑
4.  整个2与3成为 xxxAPIView (继承2, 组合继承3中任意几个)

* *进一步将get/post/put/delete方法封装并实现*, *无需实现get..等方法*
* 提供上面5个基础接口类+4个组合接口类 共 9个

```五个基础接口类
CreateAPIView  = GenericAPIView + CreateModelMixin
DestroyAPIView = GenericAPIView + DestroyModelMixin
ListAPIView    = GenericAPIView + ListModelMixin
UpdateAPIView  = GenericAPIView + UpdateModelMixin
RetrieveAPIView = GenericAPIView + RetrieveModelMixin
```

```4个组合接口类 (继承原理同上)
ListCreateAPIView
RetrieveUpdateAPIView
RetrieveDestroyAPIView
RetrieveUpdateDestroyAPIView
```

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

# get/put/delete
class BookGetPutDeleteAPIView(RetrieveUpdateDestroyAPIView):
    queryset = models.Book.objects
    serializer_class = serializers.BookModelSerializer

# get/post
class BookGetsPostAPIView(ListCreateAPIView):
    queryset = models.Book.objects
    serializer_class = serializers.BookModelSerializer
```

🆑🆑🆑🆑第五层🆑🆑🆑🆑
引入ViewSetMixin (重写as_view), ViewSet(继承APIView, ViewSetMixin)

* 让get/post/等http请求在view里与actions(create/update…)进行映射
  dispatch时直接执行self.actions方法

引入GenericViewSet(继承ViewSetMixin, GenericAPIView)

* as_view可以映射请求
* 封装了instance/serializer

5. ModelViewSet (继承上两个, 同时再继承xxModelMixin)
   * xxModelMixin提供self.actions方法,
   * ViewSetMixin 一一作了映射,
   * GenericAPIView 对instance/serializer作了封装

> 最终实现 ->  *一个类实现5个接口且无需写任何方法*

## 上完整代码

```python
# 终极写法: (仅适用于ORM操作数据库)
from rest_framework.viewsets import ModelViewSet
from rest_framework.generics import ListCreateAPIView, RetrieveUpdateDestroyAPIView

class BookModelViewSet(ModelViewSet):
    queryset = models.Book.objects
    serializer_class = serializers.BookModelSerializer
```

```
'''
=========第一层: 使用APIView==========
'''
from rest_framework.generics import GenericAPIView
from rest_framework import status

class BookGenericAPIView(views.APIView):

def get(self, request, *args, **kwargs):
        obj_list = models.Book.objects.all()
        ser = serializers.BookModelSerializer(instance=obj_list, many=True)
        return response.Response(ser.data, status=status.HTTP_200_OK)

def post(self, request, *args, **kwargs):
        ser = serializers.BookModelSerializer(data=request.data)
        if ser.is_valid():
            ser.save()
            return response.Response(data=ser.data, status=status.HTTP_200_OK)
        else:
            return response.Response(data=ser.errors, status=status.HTTP_400_BAD_REQUEST)

def put(self, request, *args, **kwargs):
        obj = models.Book.objects.filter(pk=kwargs.get('id')).first()
        ser = serializers.BookModelSerializer(instance=obj, data=request.data)
        if ser.is_valid():
            ser.save()
            return response.Response(data=ser.data, status=status.HTTP_200_OK)
        else:
            return response.Response(data=ser.errors, status=status.HTTP_406_NOT_ACCEPTABLE)

def delete(self, request, *args, **kwargs):
        obj = models.Book.objects.filter(pk=kwargs.get('id')).delete()
        if obj:
            return response.Response(data='删除成功', status=status.HTTP_200_OK)
        else:
            return response.Response(data='不存在', status=status.HTTP_200_OK)

'''
=========第二层: 无需定义对象与序列化器 =========================
        使用GenericAPIView(它继承自APIView)
=========GenericAPIView把instance和serializer进行封装=============
'''
from rest_framework.generics import GenericAPIView
from rest_framework import status

class BooksGenericAPIView(GenericAPIView):
    queryset = models.Book.objects
    serializer_class = serializers.BookModelSerializer

# 查多条
    def get(self, request, *args, **kwargs):
        obj_list = self.get_queryset()
        ser = self.get_serializer(instance=obj_list, many=True)
        return response.Response(ser.data, status=status.HTTP_200_OK)
    # 增一条
    def post(self, request, *args, **kwargs):
        print(request.data)
        ser = self.get_serializer(data=request.data)
        if ser.is_valid():
            ser.save()
            return response.Response(data=ser.data, status=status.HTTP_200_OK)
        else:
            return response.Response(data=ser.errors, status=status.HTTP_400_BAD_REQUEST)

class BookGenericAPIView(GenericAPIView):
    queryset = models.Book.objects
    serializer_class = serializers.BookModelSerializer
    # 查一条
    def get(self, request, *args, **kwargs):
        obj = self.get_object()
        ser = self.get_serializer(instance=obj)
        return response.Response(data=ser.data, status=status.HTTP_200_OK)
    # 改一条
    def put(self, request, *args, **kwargs):
        obj = self.get_object()
        ser = self.get_serializer(instance=obj, data=request.data)
        if ser.is_valid():
            ser.save()
            return response.Response(data=ser.data, status=status.HTTP_200_OK)
        else:
            return response.Response(data=ser.errors, status=status.HTTP_406_NOT_ACCEPTABLE)
    # 删一条
    def delete(self, request, *args, **kwargs):
        obj = self.get_object().delete()
        if obj:
            return response.Response(data='删除成功', status=status.HTTP_200_OK)
        else:
            return response.Response(data='不存在', status=status.HTTP_200_OK)

'''
=========第三层: 无需写执行步骤 + (需要写get/post..方法) ============
    使用GenericAPIView的同时集成xxxModelMixin(List/Create/..)
    在对象和序列化器被GenericAPIView包装的基础上
===============ModelMixin把第二层中的执行步骤进行封装================
'''
from rest_framework.generics import GenericAPIView
from rest_framework.mixins import \
    ListModelMixin, CreateModelMixin, DestroyModelMixin, UpdateModelMixin, RetrieveModelMixin

class BooksGenericAPIView(GenericAPIView,
                          ListModelMixin,
                          CreateModelMixin,):
    queryset = models.Book.objects
    serializer_class = serializers.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 BookGenericAPIView(GenericAPIView, RetrieveModelMixin,
                         UpdateModelMixin, DestroyModelMixin):
    queryset = models.Book.objects
    serializer_class = serializers.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)

'''
==================第四层: 无需写get/post..方法 ===================
    把上面的类继续封装(属性封装+方法封装) + 内部实现get/post/put/delete方法
================组合出9个xxxAPIView(同时继承Generic+xxModelMixin)==============
CreateAPIView, DestroyAPIView, ListAPIView, UpdateAPIView, RetrieveAPIView
ListCreateAPIView, RetrieveUpdateAPIView, RetrieveDestroyAPIView
RetrieveUpdateDestroyAPIView
'''
from rest_framework.generics import CreateAPIView,ListAPIView,\
    DestroyAPIView,UpdateAPIView,RetrieveAPIView,\
    ListCreateAPIView, RetrieveDestroyAPIView, RetrieveUpdateAPIView, \
    RetrieveUpdateDestroyAPIView

# get/put/delete
class BookGetPutDeleteAPIView(RetrieveUpdateDestroyAPIView):
    queryset = models.Book.objects
    serializer_class = serializers.BookModelSerializer

# get/post
class BookGetsPostAPIView(ListCreateAPIView):
    queryset = models.Book.objects
    serializer_class = serializers.BookModelSerializer

'''
=================第五层: 一个类实现5个接口 ====================
ViewSet         -> ViewSetMixin + APIView                 | 映射
GenericViewSet  -> ViewSetMixin + GenericAPIView          | 映射 + 属性封装
        ModelViewSet    -> 5中ModelMixin + GenericViewSet | 映射 + 属性封装 + 方法封装并实现get/post等方法
=================对请求方式与执行方法映射的一层封装================
ViewSetMixin: 
1.This is the magic.
2.APIView基础上重写as_view
    to create a concrete view binding the 'GET' and 'POST' methods
    to the 'list' and 'create' actions...
    view = BookViewSet.as_view({'get': 'list', 'post': 'create'})
=============================

'''
from rest_framework.viewsets import ViewSet,GenericViewSet, ModelViewSet
from rest_framework.generics import ListCreateAPIView, RetrieveUpdateDestroyAPIView

# 如下写法与第四层实现逻辑并无差别, 这就是第五层么? --不是! 第五层把下面两个类可以合二为一
class BookViewSet(RetrieveUpdateDestroyAPIView, ViewSet):
    queryset = models.Book.objects
    serializer_class = serializers.BookModelSerializer

class BooksViewSet(ListCreateAPIView, ViewSet):
    queryset = models.Book.objects
    serializer_class = serializers.BookModelSerializer

# 终极写法: (仅适用于ORM操作数据库)
class BookModelViewSet(ModelViewSet):
    queryset = models.Book.objects
    serializer_class = serializers.BookModelSerializer
```

> 上图:

![rest_framework.png](http://michael001.cn/usr/uploads/2021/04/4095575280.png)

drf 源码分析之 ModelViewSet五层演进之路(含详细图解)

Michael • 2020 年 10 月 14 日