as_view() 源码解析

 @classonlymethod
    def as_view(cls, **initkwargs):   
        """Main entry point for a request-response process."""
        for key in initkwargs:
            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__))
            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))

        def view(request, *args, **kwargs):    #只是定义了一下并没有执行
　　　　　　#　cls LoginView的实例对象
            self = cls(**initkwargs)
            if hasattr(self, 'get') and not hasattr(self, 'head'):
                self.head = self.get
            self.request = request
            self.args = args
            self.kwargs = kwargs
　　　　　　　#分发
            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     #返回一个函数对象

 

 

 

 view函数并没有执行

 

 

用户  get请求访问Login

path('/login/,'执行view(request))

 

 

#self  调的distouch  但是LOginVIew没有dispatch  ,去父类里去找

#反射  getattr

     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.
　　　　　　#

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

        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)

 

 

 

from django.views import View

class LoginView(View):
　　# 如果自己定义 dispatch 一定要return 返回值
    def dispatch(self, request, *args, **kwargs):
        print("dispatch.....")
        ret=super().dispatch(request, *args, **kwargs)
        return ret


    def get(self,request):
        print("GET....")
        return render(request,"login.html")

    def post(self,request):
        print("post.....")
        return HttpResponse("OK")

    def delete(self,request):
        pass

    def put(self,request):
        pass