개요
과정
1. urls.py에서 View 지정, as_view()
urlpatterns = [ path("/", MyView.as_view()) ]
class View: @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( "The method name %s is not accepted as a keyword argument " "to %s()." % (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) 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) view.view_class = cls view.view_initkwargs = initkwargs # __name__ and __qualname__ are intentionally left unchanged as # view_class should be used to robustly determine the name of the view # instead. view.__doc__ = cls.__doc__ view.__module__ = cls.__module__ view.__annotations__ = cls.dispatch.__annotations__ # Copy possible attributes set by decorators, e.g. @csrf_exempt, from # the dispatch method. view.__dict__.update(cls.dispatch.__dict__) # Mark the callback if the view class is async. if cls.view_is_async: markcoroutinefunction(view) return view class APIView(View): @classmethod def as_view(cls, **initkwargs): """ Store the original class on the view function. This allows us to discover information about the view when we do URL reverse lookups. Used for breadcrumb generation. """ if isinstance(getattr(cls, 'queryset', None), models.query.QuerySet): def force_evaluation(): raise RuntimeError( 'Do not evaluate the `.queryset` attribute directly, ' 'as the result will be cached and reused between requests. ' 'Use `.all()` or call `.get_queryset()` instead.' ) cls.queryset._fetch_all = force_evaluation view = super().as_view(**initkwargs) view.cls = cls view.initkwargs = initkwargs # Note: session based authentication is explicitly CSRF validated, # all other authentication is CSRF exempt. return csrf_exempt(view)
FBV(Function Based View)의 경우
def api_view(http_method_names=None): """ Decorator that converts a function-based view into an APIView subclass. Takes a list of allowed methods for the view as an argument. """ http_method_names = ['GET'] if (http_method_names is None) else http_method_names def decorator(func): WrappedAPIView = type( 'WrappedAPIView', (APIView,), {'__doc__': func.__doc__} ) # Note, the above allows us to set the docstring. # It is the equivalent of: # # class WrappedAPIView(APIView): # pass # WrappedAPIView.__doc__ = func.doc <--- Not possible to do this # api_view applied without (method_names) assert not isinstance(http_method_names, types.FunctionType), \ '@api_view missing list of allowed HTTP methods' # api_view applied with eg. string instead of list of strings assert isinstance(http_method_names, (list, tuple)), \ '@api_view expected a list of strings, received %s' % type(http_method_names).__name__ allowed_methods = set(http_method_names) | {'options'} WrappedAPIView.http_method_names = [method.lower() for method in allowed_methods] def handler(self, *args, **kwargs): return func(*args, **kwargs) for method in http_method_names: setattr(WrappedAPIView, method.lower(), handler) WrappedAPIView.__name__ = func.__name__ WrappedAPIView.__module__ = func.__module__ WrappedAPIView.renderer_classes = getattr(func, 'renderer_classes', APIView.renderer_classes) WrappedAPIView.parser_classes = getattr(func, 'parser_classes', APIView.parser_classes) WrappedAPIView.authentication_classes = getattr(func, 'authentication_classes', APIView.authentication_classes) WrappedAPIView.throttle_classes = getattr(func, 'throttle_classes', APIView.throttle_classes) WrappedAPIView.permission_classes = getattr(func, 'permission_classes', APIView.permission_classes) WrappedAPIView.schema = getattr(func, 'schema', APIView.schema) return WrappedAPIView.as_view() return decorator
FBV를 정의하는 @api_view() 데코레이터도 결국은 FBV를 APIView로 바꿔준 후 .as_view()를 실행해주는 방식으로 작동한다.
2. dispatch()
# View.dispatch()를 완전히 오버라이딩 한다 class APIView(View): def dispatch(self, request, *args, **kwargs): """ `.dispatch()` is pretty much the same as Django's regular dispatch, but with extra hooks for startup, finalize, and exception handling. """ self.args = args self.kwargs = kwargs request = self.initialize_request(request, *args, **kwargs) self.request = request self.headers = self.default_response_headers # deprecate? try: self.initial(request, *args, **kwargs) # Get the appropriate handler method 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 response = handler(request, *args, **kwargs) except Exception as exc: response = self.handle_exception(exc) self.response = self.finalize_response(request, response, *args, **kwargs) return self.response
self.request
self.request를 request로 지정해줘, handler에 request를 전달하지 않아도 APIView 에서는 언제든지 self.request로 접근이 가능하다.
그렇다면 왜 굳이 handler에 request를 전달해주는 걸까?
처음에는 FBV에서는 self.request가 따로 없을테니 그럴거라 생각했으나, FBV도 결국 APIView를 생성하는 방식으로 동작한다는 걸 알았다.
