DRF视图源码分析

本文主要是介绍DRF视图源码分析，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

DRF视图源码分析

1 APIView

class GenericAPIView(APIView):pass # 10功能class GenericViewSet(xxxx.View-2个功能, GenericAPIView):pass # 5功能能class UserView(GenericViewSet):def get(self,request):pass

APIView是drf中 “顶层” 的视图类，在他的内部主要实现drf基础的组件的使用，例如：版本、认证、权限、限流等。

# urls.pyfrom django.urls import path
from app01 import viewsurlpatterns = [path('api/users/', views.UserView.as_view()),path('api/users/<int:pk>/', views.UserDetailView.as_view()),
]

# views.pyfrom rest_framework.views import APIView
from rest_framework.response import Responseclass UserView(APIView):# 认证、权限、限流等def get(self, request):# 业务逻辑：查看列表return Response({"code": 0, 'data': "..."})def post(self, request):# 业务逻辑：新建return Response({'code': 0, 'data': "..."})class UserDetailView(APIView):# 认证、权限、限流等def get(self, request,pk):# 业务逻辑：查看某个数据的详细return Response({"code": 0, 'data': "..."})def put(self, request,pk):# 业务逻辑：全部修改return Response({'code': 0, 'data': "..."})def patch(self, request,pk):# 业务逻辑：局部修改return Response({'code': 0, 'data': "..."})def delete(self, request,pk):# 业务逻辑：删除return Response({'code': 0, 'data': "..."})

2 GenericAPIView

GenericAPIView 继承APIView，在APIView的基础上又增加了一些功能。例如：get_queryset、get_object等。

实际在开发中一般不会直接继承它，他更多的是担任 中间人的角色，为子类提供公共功能。

# urls.pyfrom django.urls import path
from app01 import viewsurlpatterns = [path('api/users/', views.UserView.as_view()),path('api/users/<int:pk>/', views.UserDetailView.as_view()),
]

# views.pyfrom rest_framework.generics import GenericAPIView
from rest_framework.response import Responseclass UserView(GenericAPIView):queryset = models.UserInfo.objects.filter(status=True)serializer_class = 序列化类def get(self, request):queryset = self.get_queryset()ser = self.get_serializer(intance=queryset,many=True)print(ser.data)return Response({"code": 0, 'data': "..."})

注意：最大的意义，将数据库查询、序列化类提取到类变量中，后期再提供公共的get/post/put/delete等方法，让开发者只定义类变量，自动实现增删改查。

3 GenericViewSet

在这里插入图片描述

GenericViewSet类中没有定义任何代码，他就是继承 ViewSetMixin 和 GenericAPIView，也就说他的功能就是将继承的两个类的功能继承到一起。

GenericViewSet在视图中的改变不大，但是在路由中写到的功能较多

GenericAPIView，将数据库查询、序列化类的定义提取到类变量中，便于后期处理。
ViewSetMixin，将 get/post/put/delete 等方法映射到 list、create、retrieve、update、partial_update、destroy方法中，让视图不再需要两个类。

# urls.pyfrom django.urls import path, re_path, include
from app01 import viewsurlpatterns = [path('api/users/', views.UserView.as_view({"get":"list","post":"create"})),path('api/users/<int:pk>/', views.UserView.as_view({"get":"retrieve","put":"update","patch":"partial_update","delete":"destory"})),
]

# views.pyfrom rest_framework.viewsets import GenericViewSet
from rest_framework.response import Responseclass UserView(GenericViewSet):# 认证、权限、限流等queryset = models.UserInfo.objects.filter(status=True)serializer_class = 序列化类def list(self, request):# 业务逻辑：查看列表queryset = self.get_queryset()ser = self.get_serializer(intance=queryset,many=True)print(ser.data)return Response({"code": 0, 'data': "..."})def create(self, request):# 业务逻辑：新建return Response({'code': 0, 'data': "..."})def retrieve(self, request,pk):# 业务逻辑：查看某个数据的详细return Response({"code": 0, 'data': "..."})def update(self, request,pk):# 业务逻辑：全部修改return Response({'code': 0, 'data': "..."})def partial_update(self, request,pk):# 业务逻辑：局部修改return Response({'code': 0, 'data': "..."})def destory(self, request,pk):# 业务逻辑：删除return Response({'code': 0, 'data': "..."})

注意：开发中一般也很少直接去继承他，因为他也属于是 中间人类，在原来 GenericAPIView 基础上又增加了一个映射而已。

4 五大类

在drf的为我们提供好了5个用于做增、删、改（含局部修改）、查列表、查单个数据的5个类（需结合 GenericViewSet 使用）。

# urls.pyfrom django.urls import path, re_path, include
from app01 import viewsurlpatterns = [path('api/users/', views.UserView.as_view({"get":"list","post":"create"})),path('api/users/<int:pk>/', views.UserView.as_view({"get":"retrieve","put":"update","patch":"partial_update","delete":"destroy"})),
]

# views.pyfrom rest_framework.viewsets import GenericViewSet
from rest_framework.mixins import (ListModelMixin, CreateModelMixin, RetrieveModelMixin, UpdateModelMixin,DestroyModelMixin, ListModelMixin
)class UserView(CreateModelMixin,RetrieveModelMixin, UpdateModelMixin, DestroyModelMixin,ListModelMixin,GenericViewSet):# 认证、权限、限流等queryset = models.UserInfo.objects.filter(status=True)serializer_class = 序列化类

在这个5个类中已帮我们写好了 list、create、retrieve、update、partial_update、destory 方法，我们只需要在根据写类变量：queryset、serializer_class即可。

示例1：

# urls.pyfrom django.urls import path
from app01 import viewsurlpatterns = [path('api/users/', views.UserView.as_view({"get": "list"})),path('api/users/<int:pk>/', views.UserView.as_view({"get": "retrieve"})),
]

# views.pyfrom rest_framework import serializers
from rest_framework.viewsets import GenericViewSet
from rest_framework import mixins
from app01 import modelsclass UserModelSerializer(serializers.ModelSerializer):level_text = serializers.CharField(source="get_level_display",read_only=True)extra = serializers.SerializerMethodField(read_only=True)class Meta:model = models.UserInfofields = ["username", "age", "email", "level_text", "extra"]def get_extra(self, obj):return 666class UserView(mixins.ListModelMixin, mixins.RetrieveModelMixin, GenericViewSet):queryset = models.UserInfo.objects.all()serializer_class = UserModelSerializer

示例2：

# urls.pyfrom django.urls import path
from app01 import viewsurlpatterns = [path('api/users/', views.UserView.as_view({"get": "list", "post": "create"})),path('api/users/<int:pk>/', views.UserView.as_view({"get": "retrieve"})),
]

# views.pyfrom rest_framework import serializers
from rest_framework.viewsets import GenericViewSet
from rest_framework import mixins
from app01 import modelsclass UserModelSerializer(serializers.ModelSerializer):level_text = serializers.CharField(source="get_level_display",read_only=True)extra = serializers.SerializerMethodField(read_only=True)class Meta:model = models.UserInfofields = ["username", "age", "email", "level_text", "extra"]def get_extra(self, obj):return 666class UserView(mixins.ListModelMixin, mixins.RetrieveModelMixin, mixins.CreateModelMixin, GenericViewSet):queryset = models.UserInfo.objects.all()serializer_class = UserModelSerializerdef perform_create(self, serializer):""" 序列化：对请求的数据校验成功后，执行保存。"""serializer.save(depart_id=1, password="123")

示例3：

# urls.pyfrom django.urls import path
from app01 import viewsurlpatterns = [path('api/users/', views.UserView.as_view({"get": "list", "post": "create"})),path('api/users/<int:pk>/', views.UserView.as_view({"get": "retrieve", "put": "update", "patch": "partial_update", "delete": "destroy"})),
]

# views.pyfrom rest_framework import serializers
from rest_framework.viewsets import GenericViewSet
from rest_framework import mixins
from app01 import modelsclass UserModelSerializer(serializers.ModelSerializer):level_text = serializers.CharField(source="get_level_display",read_only=True)extra = serializers.SerializerMethodField(read_only=True)class Meta:model = models.UserInfofields = ["username", "age", "email", "level_text", "extra"]def get_extra(self, obj):return 666class UserView(mixins.ListModelMixin,mixins.RetrieveModelMixin,mixins.CreateModelMixin,mixins.UpdateModelMixin,mixins.DestroyModelMixin,GenericViewSet):queryset = models.UserInfo.objects.all()serializer_class = UserModelSerializerdef perform_create(self, serializer):""" 序列化：对请求的数据校验成功后，执行保存。"""serializer.save(depart_id=1, password="123")def perform_update(self, serializer):serializer.save()def perform_destroy(self, instance):instance.delete()

示例4：

# urls.pyfrom django.urls import path
from app01 import viewsurlpatterns = [path('api/users/', views.UserView.as_view({"get": "list", "post": "create"})),path('api/users/<int:pk>/', views.UserView.as_view({"get": "retrieve", "put": "update", "patch": "partial_update", "delete": "destroy"})),
]

# views.py
from rest_framework import serializers
from rest_framework.viewsets import ModelViewSet
from app01 import modelsclass UserModelSerializer(serializers.ModelSerializer):level_text = serializers.CharField(source="get_level_display",read_only=True)extra = serializers.SerializerMethodField(read_only=True)class Meta:model = models.UserInfofields = ["username", "age", "email", "level_text", "extra"]def get_extra(self, obj):return 666class UserView(ModelViewSet):queryset = models.UserInfo.objects.all()serializer_class = UserModelSerializerdef perform_create(self, serializer):""" 序列化：对请求的数据校验成功后，执行保存。"""serializer.save(depart_id=1, password="123")

在开发过程中使用 五大类 或 ModelViewSet 是比较常见的，并且如果他们内部的某些功能不够用，还可以进行重新某些方法进行扩展。

问题：drf中提供了这么多视图，以后那个用的比较多？

接口与数据库操作无关，直接继承APIView
接口背后需要对数据库进行操作，一般：ModelViewSet 或 CreateModelMixin、ListModelMixin...
```
- 利用钩子自定义功能。
- 重写某个写方法，实现更加完善的功能。
```
根据自己公司的习惯，自定义：ModelViewSet 或 CreateModelMixin、ListModelMixin...

补充：权限

在之前定义权限类时，类中可以定义两个方法：has_permission 和 has_object_permission

has_permission ，在请求进入视图之前就会执行。
has_object_permission，当视图中调用 self.get_object时就会被调用（删除、更新、查看某个对象时都会调用），一般用于检查对某个对象是否具有权限进行操作。

class PermissionA(BasePermission):message = {"code": 1003, 'data': "无权访问"}def has_permission(self, request, view):exists = request.user.roles.filter(title="员工").exists()if exists:return Truereturn Falsedef has_object_permission(self, request, view, obj):return True