Django—基本视图-View

• 根视图View类

  ---

  @classonlymethod
   def as_view(cls, **initkwargs):
   """Main entry point for a request-response process."""
   # 参数检查
   for key in initkwargs:
   if key in cls.http_method_names: # 参数名不能是指定http的方法名
   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): # 参数名必须是类已有属性
   raise TypeError("%s() received an invalid keyword %r. as_view "
   "only accepts arguments that are already "
   "attributes of the class." % (cls.__name__, key))
   # 视图处理函数
   def view(request, *args, **kwargs):
   self = cls(**initkwargs) # 实例化当前类的对象
   if hasattr(self, 'get') and not hasattr(self, 'head'):
   self.head = self.get
   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__
   )
   # 方法派发
   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 # 返回视图函数

  ---

  def dispatch(self, request, *args, **kwargs):
   #检查请求方法是不是在http_method_names中包含
   #http_method_names包括八种方法：['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: #不在调用http_method_not_allowed报错
   handler = self.http_method_not_allowed
   #调用和请求方法同名的实例方法处理用户请求，实例方法需要用户自己定义
   return handler(request, *args, **kwargs)

  ---

  from django.views import View
  class IndexView(View):
   def get(self,request):
   return HttpResponse("get")
   def post(self,request):
   return HttpResponse("post")
   def put(self,request):
   return HttpResponse("put")
   def delete(self,request):
   return HttpResponse("delete")