import asyncio import logging from django.core.exceptions import ImproperlyConfigured from django.http import ( HttpResponse, HttpResponseGone, HttpResponseNotAllowed, HttpResponsePermanentRedirect, HttpResponseRedirect, ) from django.template.response import TemplateResponse from django.urls import reverse from django.utils.decorators import classonlymethod from django.utils.functional import classproperty logger = logging.getLogger("django.request") class ContextMixin: """ A default context mixin that passes the keyword arguments received by get_context_data() as the template context. """ extra_context = None def get_context_data(self, **kwargs): kwargs.setdefault("view", self) if self.extra_context is not None: kwargs.update(self.extra_context) return kwargs class View: """ Intentionally simple parent class for all views. Only implements dispatch-by-method and simple sanity checking. """ http_method_names = [ "get", "post", "put", "patch", "delete", "head", "options", "trace", ] def __init__(self, **kwargs): """ Constructor. Called in the URLconf; can contain helpful extra keyword arguments, and other things. """ # Go through keyword arguments, and either save their values to our # instance, or raise an error. for key, value in kwargs.items(): setattr(self, key, value) @classproperty def view_is_async(cls): handlers = [ getattr(cls, method) for method in cls.http_method_names if (method != "options" and hasattr(cls, method)) ] if not handlers: return False is_async = asyncio.iscoroutinefunction(handlers[0]) if not all(asyncio.iscoroutinefunction(h) == is_async for h in handlers[1:]): raise ImproperlyConfigured( f"{cls.__qualname__} HTTP handlers must either be all sync or all " "async." ) return is_async @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: view._is_coroutine = asyncio.coroutines._is_coroutine return view def setup(self, request, *args, **kwargs): """Initialize attributes shared by all view methods.""" if hasattr(self, "get") and not hasattr(self, "head"): self.head = self.get self.request = request self.args = args self.kwargs = kwargs 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) def http_method_not_allowed(self, request, *args, **kwargs): logger.warning( "Method Not Allowed (%s): %s", request.method, request.path, extra={"status_code": 405, "request": request}, ) response = HttpResponseNotAllowed(self._allowed_methods()) if self.view_is_async: async def func(): return response return func() else: return response def options(self, request, *args, **kwargs): """Handle responding to requests for the OPTIONS HTTP verb.""" response = HttpResponse() response.headers["Allow"] = ", ".join(self._allowed_methods()) response.headers["Content-Length"] = "0" if self.view_is_async: async def func(): return response return func() else: return response def _allowed_methods(self): return [m.upper() for m in self.http_method_names if hasattr(self, m)] class TemplateResponseMixin: """A mixin that can be used to render a template.""" template_name = None template_engine = None response_class = TemplateResponse content_type = None def render_to_response(self, context, **response_kwargs): """ Return a response, using the `response_class` for this view, with a template rendered with the given context. Pass response_kwargs to the constructor of the response class. """ response_kwargs.setdefault("content_type", self.content_type) return self.response_class( request=self.request, template=self.get_template_names(), context=context, using=self.template_engine, **response_kwargs, ) def get_template_names(self): """ Return a list of template names to be used for the request. Must return a list. May not be called if render_to_response() is overridden. """ if self.template_name is None: raise ImproperlyConfigured( "TemplateResponseMixin requires either a definition of " "'template_name' or an implementation of 'get_template_names()'" ) else: return [self.template_name] class TemplateView(TemplateResponseMixin, ContextMixin, View): """ Render a template. Pass keyword arguments from the URLconf to the context. """ def get(self, request, *args, **kwargs): context = self.get_context_data(**kwargs) return self.render_to_response(context) class RedirectView(View): """Provide a redirect on any GET request.""" permanent = False url = None pattern_name = None query_string = False def get_redirect_url(self, *args, **kwargs): """ Return the URL redirect to. Keyword arguments from the URL pattern match generating the redirect request are provided as kwargs to this method. """ if self.url: url = self.url % kwargs elif self.pattern_name: url = reverse(self.pattern_name, args=args, kwargs=kwargs) else: return None args = self.request.META.get("QUERY_STRING", "") if args and self.query_string: url = "%s?%s" % (url, args) return url def get(self, request, *args, **kwargs): url = self.get_redirect_url(*args, **kwargs) if url: if self.permanent: return HttpResponsePermanentRedirect(url) else: return HttpResponseRedirect(url) else: logger.warning( "Gone: %s", request.path, extra={"status_code": 410, "request": request} ) return HttpResponseGone() def head(self, request, *args, **kwargs): return self.get(request, *args, **kwargs) def post(self, request, *args, **kwargs): return self.get(request, *args, **kwargs) def options(self, request, *args, **kwargs): return self.get(request, *args, **kwargs) def delete(self, request, *args, **kwargs): return self.get(request, *args, **kwargs) def put(self, request, *args, **kwargs): return self.get(request, *args, **kwargs) def patch(self, request, *args, **kwargs): return self.get(request, *args, **kwargs)