drf 前戏—CBV的使用及源码流程
参考文献:https://www.cnblogs.com/wupeiqi/articles/7805382.html
视图:django的视图分为FBV
与CBV
反射的相关知识:https://www.cnblogs.com/Blogwj123/p/15828380.html
getattr('对象','属性名')
1.django的CBV
urlpatterns = [
# path('admin/', admin.site.urls),
# path('index/',views.index)
path('index/',views.Index.as_view())
]
from django.shortcuts import render
from django.views import View
from django.http.response import JsonResponse
# Create your views here.
def index(request):
ret={'msg':'hello world'}
return JsonResponse(ret)
class Index(View):
def get(self,request):
ret = {'msg': 'CBV hello world'}
return JsonResponse(ret)
2.CBV源码
-
View中支持的请求方式
# 源码中的支持方式,http的请求方式 http_method_names = ['get', 'post', 'put', 'patch', 'delete', 'head', 'options', 'trace']
-
在django的路由系统中,一个路由对应一个函数;执行父类的:
as_view()
@classonlymethod def as_view(cls, **initkwargs): """Main entry point for a request-response process.""" for key in initkwargs: '''查看文件''' def view(request, *args, **kwargs): self = cls(**initkwargs)# 实例化Index对象 self.setup(request, *args, **kwargs) if not hasattr(self, 'request'): raise AttributeError( "%s instance has no 'request' attribute. Did you override " "setup() and forget to call super()?" % cls.__name__ ) return self.dispatch(request, *args, **kwargs) #执行dispatch方法 view.view_class = cls view.view_initkwargs = initkwargs update_wrapper(view, cls, updated=()) update_wrapper(view, cls.dispatch, assigned=()) return view #返回函数view
说明:通过执
as_view()
每个视图函数都会执行dispatch()
方法。def dispatch(self, request, *args, **kwargs): '''源码''' if request.method.lower() in self.http_method_names: handler = getattr(self, request.method.lower(), self.http_method_not_allowed) else: handler = self.http_method_not_allowed return handler(request, *args, **kwargs)
3.扩展源码功能
说明:当子类没有方法时执行父类的,子类有值的时候执行子类(当前对象)的方法。
class Index(View):
def dispatch(self, request, *args, **kwargs):
return HttpResponse("dispatch") # 返回dispatch
def get(self,request,*args,**kwargs):
self.dispatch()
ret = {'msg': 'CBV hello world'}
return JsonResponse(ret)
# Create your views here.
def index(request):
ret={'msg':'hello world'}
if request.method=='POST':#request.method会把请求字母变化为大写
pass
return JsonResponse(ret)
class Index(View):
def dispatch(self, request, *args, **kwargs):
'''自定义dispatch'''
func=getattr(self,request.method.lower())# self相当于对象。request.menthod获取当前请求的方式,使用反射
ret=func(request,*args,**kwargs) # 加括号执行改函数,
return ret
def get(self,request,*args,**kwargs):
# self.dispatch()
ret = {'msg': 'CBV hello world'}
return JsonResponse(ret)
def dispatch(self, request, *args, **kwargs):
print("执行前")
ret=super(Index,self).dispatch(request, *args, **kwargs)
print("执行后")
return ret
from django.shortcuts import render,HttpResponse
from django.views import View
from django.http.response import JsonResponse
# Create your views here.
class MyBaseView(object):
def dispatch(self, request, *args, **kwargs):
print("执行前")
ret=super(Index,self).dispatch(request, *args, **kwargs)
# super()指当前对象父类,并不是某个类的父类,抽取出来可以供其他类的视图调用
print("执行后")
return ret
def index(request):
ret={'msg':'hello world'}
if request.method=='POST':#request.method会把请求字母变化为大写
pass
return JsonResponse(ret)
class Index(MyBaseView,View):
def get(self,request,*args,**kwargs):
# self.dispatch()
ret = {'msg': 'CBV hello world'}
return JsonResponse(ret)
class StudentView(MyBaseView,View):
'''
MyBaseView写在左边才会生效,因为View中存在默认的dispatch()方法。
面向对象中多继承左面优先(特殊情况下按照C3算法的进行继承)
'''
pass
4.使用django开发接口
- 根据
method
不同做不同的操作;
4.1 基于FBV开发
urlpatterns = [
re_path(r'^order/', views.order),
]
# 根据不同的请求方式完成不同的操作
def order(request):
if request.method == 'GET':
return HttpResponse('获取订单')
elif request.method == 'POST':
return HttpResponse('创建订单')
elif request.method == 'PUT':
return HttpResponse('更新订单')
elif request.method == 'DELETE':
return HttpResponse('删除订单')
4.2 基于CBV
urlpatterns = [
re_path(r'^order/', views.OrderView.as_view()),
]
# 根据不同的请求方式完成不同的操作
class OrderView(View):
def get(self,request,*args,**kwargs):
return HttpResponse('获取订单')
def post(self,request,*args,**kwargs):
return HttpResponse('创建订单')
def put(self,request,*args,**kwargs):
return HttpResponse('更新订单')
def delete(self,request,*args,**kwargs):
return HttpResponse('删除订单')
说明:推荐使用CBV
进行开发。
5.drf 引入
5.1 安装
pip install djangorestframework
5.2 介绍
- REST与技术无关,代表的是一种软件架构风格,REST是Representational State Transfer的简称,中文翻译为表征状态转移。
- REST从资源的角度类审视整个网络,它将分布在网络中某个节点的资源通过
URL
进行标识,客户端应用通过URL
来获取资源的表征,获得这些表征致使这些应用转变状态; - 所有的数据,不过是通过网络获取的还是操作(增删改查)的数据,都是资源,将一切数据视为资源是REST区别与其他架构风格的最本质属性;
- 对于REST这种面向资源的架构风格,有人提出一种全新的结构理念,即:面向资源架构(ROA:Resource Oriented Architecture)
继续努力,终成大器!