CBV和APIView源码分析

CBV源码分析

　　查看源码的方式，先查看自身，没有去找父类，父类没有就去找父父类。。。

自己定义的类

class Author(View):
    def get(self,request):
        back_dic = {'status_code': 100, 'msg': 'get ok'}
        return JsonResponse(back_dic)
 
    def post(self,request):
        back_dic = {'status_code': 102, 'msg': 'post ok'}
        return JsonResponse(back_dic)

我们看到自己定义的类中并没有这个as_view()方法，那么他只能是从我们继承的父类View中来的，那我们就点到View里面去看有没有as_view()这个方法

刚好就在这个里面，然后点开这个方法，看里面具体做了什么操作

    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):
            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
            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

CBV as_view()源码

简单分析，如图

我们看到，调用了as_view()实际上是走了view方法，然后再view方法中给我们返回了一个对象的dispatch方法，那么我们就得搞清楚，现在的self是谁~

self是View的对象，然后我们自定义的类继承了View，所以说self就是我们自己定义类的对象，那么就简单了，我们先去自己定义的类中找我们有没有写dispatch方法，没有再去找父类

父类中dispatch方法源码

    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.
        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)

源码分析

此时的handler就是我们发送的请求方式，比如GET，但是是小写的而已，然后再自己定义的类中与get对应上了，所以就会get请求走get，post请求走post。

此处的精髓通过反射取到请求方式