django 之(二) --- 源码分析

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CBV类视图继承

CBV：继承自View；注册的时候使用的as_view()
入口
- 不能使用请求方法的名字作为参数的名字
- 只能接受已经存在的属性对应的参数
- 定义了一个view
  - 创建了一个类视图对象
  - 保留，拷贝传递进来的属性和参数
  - 调用dispatch方法
    - 分发
    - 如果请求方法在我们的允许的列表中
      - 从自己这个对象中获取请求方法名字小写对应的属性，如果没有找到，会给一个默认http_method_not_allowded
    - 如果请求方法不在我们允许的列表中，直接就是http_method_not_allowed
    - 之后将参数传递，调用函数
默认实现了options
- 获取接口信息，可以获取接口都允许什么请求

类视图继承自View；注册时使用as_view()

 from django.conf.urls import url

 from CBV import views

 urlpatterns = [

     url(r'^hello/', views.HelloCBV.as_view(msg='Sleeping'), name='hello'),

     url(r'^books/', views.BooksCBV.as_view(), name='books'),

 ]

as_view 源码(base.py文件中)
流程：as_view --> dispatch分发 --> 调用实现请求方法对应的函数名

 class View(object):

     """

     Intentionally simple parent class for all views. Only implements

     dispatch-by-method and simple sanity checking.

     """

 　　 # 允许的请求方法

     http_method_names = ['get', 'post', 'put', 'patch', 'delete', 'head', 'options', 'trace']

     def __init__(self, **kwargs):

         """

         Constructor. Called in the URLconf; can contain helpful extra

         keyword arguments, and other things.

         """

         # Go through keyword arguments, and either save their values to our

         # instance, or raise an error.

         for key, value in six.iteritems(kwargs):

             setattr(self, key, value)

     @classonlymethod

     def as_view(cls, **initkwargs):

         """

         Main entry point for a request-response process.

         """

         for key in initkwargs:
　　　　　　　　　　# 判断，不可以使用请求方法的名字作为参数名字

             if key in cls.http_method_names:

                 raise TypeError("You tried to pass in the %s method name as a "

                                 "keyword argument to %s(). Don't do that."

                                 % (key, cls.__name__))
　　　　　　　　　　# 只能接收类视图中已经存在的属性作为参数名（路由中的变量名要和视图函数中的属性名相同）

             if not hasattr(cls, key):

                 raise TypeError("%s() received an invalid keyword %r. as_view "

                                 "only accepts arguments that are already "

                                 "attributes of the class." % (cls.__name__, key))

 　　　　　# 定义了一个view

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

             self = cls(**initkwargs)

             if hasattr(self, 'get') and not hasattr(self, 'head'):

                 self.head = self.get # 默认get请求和head请求方式一样；支持get就支持head请求

             self.request = request   # 将请求的参数，属性记录下来(三行)

             self.args = args

             self.kwargs = kwargs
　　　　　　　　　 # 返回时调用dispatch方法

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

         view.view_class = cls

         view.view_initkwargs = initkwargs

         # take name and docstring from class

         update_wrapper(view, cls, updated=())

         # and possible attributes set by decorators

         # like csrf_exempt from dispatch

         update_wrapper(view, cls.dispatch, assigned=())

         return view

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

         # Try to dispatch to the right method; if a method doesn't exist,

         # defer to the error handler. Also defer to the error handler if the

         # request method isn't on the approved list.
　　　　　　　# 将请求方法名变为小写，并判断请求方法名是否在允许的请求列表中

         if request.method.lower() in self.http_method_names:
　　　　　　　　　 # 如果在允许的请求列表中，从自己的对象中去获取请求方法名字小写的属性，没有找到给变量一个默认值

             handler = getattr(self, request.method.lower(), self.http_method_not_allowed)

         else: # 如果请求方法不在被允许的请求列表中，则http_method_not_allowd给变量

             handler = self.http_method_not_allowed

         return handler(request, *args, **kwargs)

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

         logger.warning(

             'Method Not Allowed (%s): %s', request.method, request.path,

             extra={'status_code': 405, 'request': request}

         )

         return http.HttpResponseNotAllowed(self._allowed_methods())

 
　　　　# 获取接口信息，获取接口都允许接收什么请求

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

         """

         Handles responding to requests for the OPTIONS HTTP verb.

         """

         response = http.HttpResponse()

         response['Allow'] = ', '.join(self._allowed_methods())

         response['Content-Length'] = ''

         return response

     def _allowed_methods(self):

         return [m.upper() for m in self.http_method_names if hasattr(self, m)]

类视图子类

[这些子类和模版是高度耦合的，在前后端分离中不会被使用。Mixin：只要继承中有此单词，就表示混合多继承]

TemplateView是多继承的子类，继承自：

View：分发函数：dispatch

ContextMixin：接收上下文(从视图函数传递到模板的内容)。函数：get_context_data

TemplateResponseMixin：将内容渲染到模板中。属性：template_name、template_engine、response_class、content_type。函数：render_to_response

base.py 源码分析

 # TemplateView

 class TemplateView(TemplateResponseMixin, ContextMixin, View):

     """

     A view that renders a template.  This view will also pass into the context

     any keyword arguments passed by the URLconf.

     """

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

         context = self.get_context_data(**kwargs)

         return self.render_to_response(context)

views.py 使用

 from django.views.generic import TemplateView

 # CBV继承TemplateView，实现了get请求，继承自：TemplateResponseMixin, ContextMixin, View(实现请求分发)

 class HelloTemplateView(TemplateView):

     template_name = 'hello.html'

ListView是多继承子类。继承自：

MultipleObjectTemplateResponseMixin
- TemplateResponseMixin
- 获取模板名字，首先根据template_name获取；如果没找到，自己根据应用的名字，关联模型的名字，_list.html 去查找，App/book_list.html
BaseListView
- MultipleObjectMixin
  - ContextMixin、get_queryset、model
- View：默认实现了get，渲染成了response

views.py 使用

 from django.views.generic import ListView

 from App.models import Book

 # CBV继承ListView，实现了get请求。获取一个集合数据

 # ListView继承自：MultipleObjectTemplateResponseMixin, BaseListView

 class HelloListView(ListView):

     template_name = 'BookList.html'

     model = Book

book.html

 <body>

     <ul>

         {% for book in object_list %}

             <li><a href="{% url 'cbv:single' pk=book.id %}">{{ book.b_name }}</a></li>

         {% endfor %}

     </ul>

 </body>

DetailView是多继承子类。继承自：

SingleObjectTemplateResponseMixin

- TemplateResponseMixin：重写了获取模板名字的方法

BaseDetailView

- View、SingleObjectMixin

views.py 使用

 from django.views.generic import DetailView

 from App.models import Book

 # CBV继承DetailView。继承自SingleObjectTemplateResponseMixin, BaseDetailView

 class HeDetailView(DetailView):

     # template_name = 'Book.html'  #. 如果不指定模版，自动去查找名字为：book_detail.html的模版

     # model = Book

     queryset = Book.objects.all()

urls.py

 from django.conf.urls import url

 from App import views

 urlpatterns = [ # 单一实例：pk、slug

     url(r'^single/(?P<pk>\d+)/', views.HeDetailView.as_view(), name='single'),

 ]

APIView源码分析

APIView源码封装的类及用途

renderer_classes：渲染的类

parser_classes：解析转换的类

authentication_classes：认证的类

throttle_classes：节流的类、控制请求频率的[此接口每分钟请求多少次]

permission_classes：权限的类

content_negotiation_class：内容过滤类

metadata_class：元信息的类

versioning_class：版本控制的类

as_view( )方法：调用父类中的as_view。对dispatch重写，主要做dispatch分发。
- 重写的dispatch方法中的 initialize_request 方法初始化一个新的request。
- 使用django的request构建了一个REST中的Request，
- 将Django中的Request作为了自己的一个私有属性 _request
- (若在rest_formwork中获取django的request，需要request._reuqest)
  - initial 初始化。获取接受的渲染、获取接受的类型、版本是否支持
    - perform_authentication：
      - 执行用户认证。request.user[.user中将方法改为属性，并进行认证]
        
        遍历用户认证器，如果认证成功会返回一个元组
        
        元组中的第一个元素就是 user
        
        第二个元素就是 auth [token]
    - check_permissions
      - 检查用户权限
        
        遍历权限检测器
        
        只要有一个权限检测没通过就直接显示权限被拒绝
        
        只有所有权限都满足，才算是拥有权限
    - check_throttles
      - 检测访问频率
        
        遍历频率限制器
        
        如果验证不通过，就需要等待
csrf_exempt
- 所有APIView的子类都是csrf豁免的

Request源码分析

Request
- 它是rest_framework的request。(rest_framework.request)
- 将Django中的Request作为了自己的一个属性 _request
- 属性和方法
  - content_type：传输内容的类型
  - stream：流
  - query_params：查询参数。[可以在post请求中获取GET参数][将Django中的request.GET方法改名为query_params]
  - data：处理任意数据，同时兼容 POST,PUT,PATCH
  - user：可以直接在请求上获取用户。[相当于在请求上添加一个用户对象属性]
  - auth：认证。相当于请求上添加了一个属性，属性值是token
  - successful_authenticator：认证成功

Response源码分析

Response
- 依然是HttpResponse的子类。只要类视图继承自APIView后，
- Response自己封装的data 直接接受字典转换成JSON [ Response(data=request.data, status(状态码)=201) ]
- 属性和方法
  - rendered_content：渲染的内容
  - status_text：状态码转成常量
    - 封装 status模块中，实际上就是一个常量类

针对视图函数的包装

REST框架提供了两种可用于编写API视图的包装器(wrappers)

- CBV：APIView
- FBV：添加 @api_view装饰器；必须手动指定允许的请求方法
  - @api_view(http_method_names=['GET', 'POST'])

 from rest_framework import status

 from rest_framework.decorators import api_view

 from rest_framework.response import Response

 from RestSerializers.serializers import BookSerializer

 @api_view(http_method_names=['GET', 'POST'])

 def books(request):

     print(type(request))

     if request.method == "GET":

         return Response(data={"msg": "get ok"})

     elif request.method == "POST":

         print(request.data)

         book_serializer = BookSerializer(data=request.data)

         if book_serializer.is_valid():

             book_serializer.save()

             return Response(data=book_serializer.data)

         return Response(data={'msg': 'error'}, status=status.HTTP_400_BAD_REQUEST)

APIView类视图子类

GenericAPIView继承自APIView；GenericAPIView是一个基类

generics包中。子类：
- GenericAPIView
  - 增加的模型的获取操作
  - get_queryset：获取查询结果集
  - get_object：获取单个对象。lookup_field 默认pk
  - get_serializer：序列化实例
  - get_serializer_class：获取序列化类
  - get_serializer_context：获取序列化上下文内容
  - filter_queryset：对查询结果集过滤
  - paginator：　　直接构件的分页器
  - paginate_queryset：对查询结果集分页
  - get_paginated_response：获取分页后的结果
- CreateAPIView
  - 创建的类视图。实现了post进行创建
  - 继承自GenericAPIView
  - 继承自CreateModelMixin
- ListAPIView
  - 列表的类视图。实现了get
  - 继承自GenericAPIView
  - 继承自ListModelMixin
- RetrieveAPIView
  - 查询单个数据的类视图。实现了get
  - 继承自GenericAPIView
  - 继承自RetrieveModelMixin
- DestroyAPIView
  - 销毁数据的类视图，删除数据的类视图。实现了delete
  - 继承自GenericAPIView
  - 继承自DestroyModelMixin
- UpdateAPIView
  - 更新数据的类视图。实现了put、patch
  - 继承自GenericAPIView
  - 继承自UpdateModelMixin
- ListCreateAPIView
  - 获取列表数据，创建数据的类视图。实现了get、post
  - 继承自GenericAPIView
  - 继承自ListModelMixin
  - 继承自CreateModelMixin
- RetrieveUpdateAPIView
  - 获取单个数据，更新单个数据的类视图。实现了get、put、patch
  - 继承自GenericAPIView
  - 继承自RetrieveModelMixin
  - 继承自UpdateModelMixin
- RetrieveDestroyAPIView
  - 获取单个数据，删除单个数据。实现了get、delete
  - 继承自GenericAPIView
  - 继承自RetrieveModelMixin
  - 继承自DestroyModelMixin
- RetrieveUpdateDestroyAPIView
  - 获取单个数据，更新单个数据，删除单个数据的类视图。实现了get、put、patch、delete
  - 继承自GenericAPIView
  - 继承自RetrieveModelMixin
  - 继承自UpdateModelMixin
  - 继承自DestroyModelMixin
mixins
- CreateModelMixin
  - create
  - perform_create
  - get_success_headers
- ListModelMixin
  - list：查询结果集，添加分页，帮你序列化
- RetrieveModelMixin
  - retrieve：获取单个对象并进行序列化
- DestroyModelMixin
  - destroy：
    - 获取单个对象
    - 调用执行删除
    - 返回Respon 状态码204
  - perform_destroy
    - 默认是模型的delete
    - 如果说数据的逻辑删除。重写进行保存
- UpdateModelMixin
  - update：获取对象，合法验证；执行更新
  - perform_update
  - partial_update：差量更新，对应的就是patch
viewsets继承自：
- ViewSetMixin：
  - 重写as_view。添加过滤和反向解析
- GenericViewSet
  - 继承自GenericAPIView
  - 继承自ViewSetMixin
- ViewSet
  - 继承自APIView
  - 继承自ViewSetMixin
  - 默认啥都不支持，需要自己手动实现
- ReadOnlyModelViewSet
  - 只读的模型的视图集合
  - 继承自RetrieveModelMixin
  - 继承自ListModelMixin
  - 继承自GenericViewSet
- ModelViewSet
  - 直接封装对象的所有操作
  - 继承自GenericViewSet
  - 继承自CreateModelMixin
  - 继承自RetrieveModelMixin
  - 继承自UpdateModelMixin
  - 继承自DestroyModelMixin
  - 继承自ListModelMixin

封装使用1：

user/serializers.py

 from rest_framework import serializers

 from user.models import User

 # ModelSerializer没有超链接的序列化

 class SingleUserSerializer(serializers.ModelSerializer):

     class Meta:

         model = User

         fields = ['id', 'username', 'password', 'phone',]

user/models.py

 from django.db import models

 class User(models.Model):

     username = models.CharField(max_length=20, unique=True)

     password = models.CharField(max_length=128)

     phone = models.CharField(max_length=11)

     add_time = models.DateTimeField(auto_now=True)

     class Meta:

         db_table = 'user'

     def __str__(self):

         return self.username

user/views.py

from rest_framework.generics import ListCreateAPIView, RetrieveUpdateDestroyAPIView

from user.models import User

from user.serializers import SingleUserSerializer

class UserResouce(ListCreateAPIView):

    # 操作的模型

    queryset = User.objects.all()

    # 此模型对应的序列化类

    serializer_class = SingleUserSerializer

class UserResourcePro(RetrieveUpdateDestroyAPIView):

    queryset = User.objects.all()

    serializer_class = SingleUserSerializer

user/urls.py

 from django.urls import path

 from user.views import UserResouce, UserResourcePro 

 app_name = 'user'

 urlpatterns = [

     path('single', UserResouce.as_view(), name='single'),

     path('singlepro/<int:pk>', UserResourcePro.as_view(), name='singlepro'),

 ]

终极封装：

user/views.py

 from rest_framework.viewsets import ModelViewSet

 from user.models import User

 from user.serializers import SingleUserSerializer

 class UserResourceVPro(ModelViewSet):

     queryset = User.objects.all()

     serializer_class = SingleUserSerializer

user/urls.py

 from django.urls import path, include

 from rest_framework.routers import DefaultRouter

 from user.views import UserResourceVPro

 router = DefaultRouter()

 router.register(r'single', UserResourceVPro)

 # 此方式也可以获取单个对象：http://127.0.0.1:8000/user/single/2/

   # 主路由中
 8 urlpatterns = [

     path('', include(router.urls))

 ]

封装使用2：

urls.py

 from django.conf.urls import url, include

 from django.contrib import admin

 from App.urls import router

 urlpatterns = [

     url(r'^admin/', admin.site.urls),

     url(r'^app/', include('App.urls')),

     url(r'^app/', include(router.urls)),

 ]

App/urls.py

 from django.conf.urls import url

 from rest_framework.routers import DefaultRouter

 from App import views

 from App.views import GameModelViewSet

 urlpatterns = [

     url(r'^games/$', views.GamesView.as_view()),

     url(r'^games/(?P<pk>\d+)/$', views.GameView.as_view(), name='game-detail'),

 ]

11 router = DefaultRouter()

12 router.register(r'progames', GameModelViewSet)

App/models.py

 from django.db import models

 class Game(models.Model):

     g_name = models.CharField(max_length=32)

     g_price = models.FloatField(default=0)

App/serializers.py

 from rest_framework import serializers

 from App.models import Game

 # HyperlinkedModelSerializer带超链接的序列化

 class GameSerializer(serializers.HyperlinkedModelSerializer):

     class Meta:

         model = Game

         fields = ('url', 'id', 'g_name', 'g_price')

App/views.py

 from rest_framework.generics import ListCreateAPIView, RetrieveUpdateDestroyAPIView

 from rest_framework.viewsets import ModelViewSet

 from App.models import Game

 from App.serializers import GameSerializer

 class GamesView(ListCreateAPIView):

     serializer_class = GameSerializer

     queryset = Game.objects.all()

 class GameView(RetrieveUpdateDestroyAPIView):

     serializer_class = GameSerializer

     queryset = Game.objects.all()

 class GameModelViewSet(ModelViewSet):

     serializer_class = GameSerializer

     queryset = Game.objects.all()