374 lines
14 KiB
Python
374 lines
14 KiB
Python
import asyncio
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import logging
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import types
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from asgiref.sync import async_to_sync, iscoroutinefunction, sync_to_async
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from django.conf import settings
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from django.core.exceptions import ImproperlyConfigured, MiddlewareNotUsed
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from django.core.signals import request_finished
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from django.db import connections, transaction
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from django.urls import get_resolver, set_urlconf
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from django.utils.log import log_response
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from django.utils.module_loading import import_string
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from .exception import convert_exception_to_response
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logger = logging.getLogger("django.request")
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class BaseHandler:
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_view_middleware = None
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_template_response_middleware = None
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_exception_middleware = None
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_middleware_chain = None
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def load_middleware(self, is_async=False):
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"""
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Populate middleware lists from settings.MIDDLEWARE.
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Must be called after the environment is fixed (see __call__ in subclasses).
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"""
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self._view_middleware = []
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self._template_response_middleware = []
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self._exception_middleware = []
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get_response = self._get_response_async if is_async else self._get_response
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handler = convert_exception_to_response(get_response)
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handler_is_async = is_async
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for middleware_path in reversed(settings.MIDDLEWARE):
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middleware = import_string(middleware_path)
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middleware_can_sync = getattr(middleware, "sync_capable", True)
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middleware_can_async = getattr(middleware, "async_capable", False)
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if not middleware_can_sync and not middleware_can_async:
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raise RuntimeError(
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"Middleware %s must have at least one of "
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"sync_capable/async_capable set to True." % middleware_path
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)
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elif not handler_is_async and middleware_can_sync:
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middleware_is_async = False
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else:
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middleware_is_async = middleware_can_async
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try:
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# Adapt handler, if needed.
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adapted_handler = self.adapt_method_mode(
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middleware_is_async,
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handler,
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handler_is_async,
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debug=settings.DEBUG,
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name="middleware %s" % middleware_path,
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)
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mw_instance = middleware(adapted_handler)
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except MiddlewareNotUsed as exc:
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if settings.DEBUG:
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if str(exc):
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logger.debug("MiddlewareNotUsed(%r): %s", middleware_path, exc)
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else:
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logger.debug("MiddlewareNotUsed: %r", middleware_path)
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continue
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else:
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handler = adapted_handler
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if mw_instance is None:
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raise ImproperlyConfigured(
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"Middleware factory %s returned None." % middleware_path
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)
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if hasattr(mw_instance, "process_view"):
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self._view_middleware.insert(
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0,
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self.adapt_method_mode(is_async, mw_instance.process_view),
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)
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if hasattr(mw_instance, "process_template_response"):
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self._template_response_middleware.append(
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self.adapt_method_mode(
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is_async, mw_instance.process_template_response
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),
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)
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if hasattr(mw_instance, "process_exception"):
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# The exception-handling stack is still always synchronous for
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# now, so adapt that way.
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self._exception_middleware.append(
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self.adapt_method_mode(False, mw_instance.process_exception),
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)
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handler = convert_exception_to_response(mw_instance)
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handler_is_async = middleware_is_async
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# Adapt the top of the stack, if needed.
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handler = self.adapt_method_mode(is_async, handler, handler_is_async)
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# We only assign to this when initialization is complete as it is used
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# as a flag for initialization being complete.
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self._middleware_chain = handler
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def adapt_method_mode(
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self,
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is_async,
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method,
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method_is_async=None,
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debug=False,
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name=None,
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):
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"""
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Adapt a method to be in the correct "mode":
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- If is_async is False:
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- Synchronous methods are left alone
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- Asynchronous methods are wrapped with async_to_sync
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- If is_async is True:
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- Synchronous methods are wrapped with sync_to_async()
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- Asynchronous methods are left alone
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"""
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if method_is_async is None:
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method_is_async = iscoroutinefunction(method)
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if debug and not name:
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name = name or "method %s()" % method.__qualname__
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if is_async:
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if not method_is_async:
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if debug:
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logger.debug("Synchronous handler adapted for %s.", name)
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return sync_to_async(method, thread_sensitive=True)
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elif method_is_async:
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if debug:
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logger.debug("Asynchronous handler adapted for %s.", name)
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return async_to_sync(method)
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return method
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def get_response(self, request):
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"""Return an HttpResponse object for the given HttpRequest."""
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# Setup default url resolver for this thread
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set_urlconf(settings.ROOT_URLCONF)
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response = self._middleware_chain(request)
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response._resource_closers.append(request.close)
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if response.status_code >= 400:
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log_response(
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"%s: %s",
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response.reason_phrase,
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request.path,
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response=response,
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request=request,
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)
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return response
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async def get_response_async(self, request):
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"""
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Asynchronous version of get_response.
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Funneling everything, including WSGI, into a single async
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get_response() is too slow. Avoid the context switch by using
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a separate async response path.
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"""
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# Setup default url resolver for this thread.
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set_urlconf(settings.ROOT_URLCONF)
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response = await self._middleware_chain(request)
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response._resource_closers.append(request.close)
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if response.status_code >= 400:
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await sync_to_async(log_response, thread_sensitive=False)(
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"%s: %s",
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response.reason_phrase,
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request.path,
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response=response,
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request=request,
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)
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return response
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def _get_response(self, request):
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"""
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Resolve and call the view, then apply view, exception, and
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template_response middleware. This method is everything that happens
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inside the request/response middleware.
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"""
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response = None
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callback, callback_args, callback_kwargs = self.resolve_request(request)
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# Apply view middleware
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for middleware_method in self._view_middleware:
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response = middleware_method(
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request, callback, callback_args, callback_kwargs
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)
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if response:
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break
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if response is None:
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wrapped_callback = self.make_view_atomic(callback)
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# If it is an asynchronous view, run it in a subthread.
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if iscoroutinefunction(wrapped_callback):
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wrapped_callback = async_to_sync(wrapped_callback)
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try:
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response = wrapped_callback(request, *callback_args, **callback_kwargs)
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except Exception as e:
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response = self.process_exception_by_middleware(e, request)
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if response is None:
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raise
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# Complain if the view returned None (a common error).
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self.check_response(response, callback)
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# If the response supports deferred rendering, apply template
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# response middleware and then render the response
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if hasattr(response, "render") and callable(response.render):
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for middleware_method in self._template_response_middleware:
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response = middleware_method(request, response)
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# Complain if the template response middleware returned None
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# (a common error).
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self.check_response(
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response,
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middleware_method,
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name="%s.process_template_response"
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% (middleware_method.__self__.__class__.__name__,),
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)
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try:
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response = response.render()
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except Exception as e:
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response = self.process_exception_by_middleware(e, request)
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if response is None:
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raise
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return response
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async def _get_response_async(self, request):
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"""
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Resolve and call the view, then apply view, exception, and
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template_response middleware. This method is everything that happens
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inside the request/response middleware.
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"""
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response = None
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callback, callback_args, callback_kwargs = self.resolve_request(request)
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# Apply view middleware.
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for middleware_method in self._view_middleware:
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response = await middleware_method(
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request, callback, callback_args, callback_kwargs
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)
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if response:
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break
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if response is None:
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wrapped_callback = self.make_view_atomic(callback)
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# If it is a synchronous view, run it in a subthread
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if not iscoroutinefunction(wrapped_callback):
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wrapped_callback = sync_to_async(
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wrapped_callback, thread_sensitive=True
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)
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try:
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response = await wrapped_callback(
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request, *callback_args, **callback_kwargs
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)
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except Exception as e:
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response = await sync_to_async(
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self.process_exception_by_middleware,
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thread_sensitive=True,
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)(e, request)
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if response is None:
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raise
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# Complain if the view returned None or an uncalled coroutine.
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self.check_response(response, callback)
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# If the response supports deferred rendering, apply template
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# response middleware and then render the response
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if hasattr(response, "render") and callable(response.render):
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for middleware_method in self._template_response_middleware:
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response = await middleware_method(request, response)
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# Complain if the template response middleware returned None or
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# an uncalled coroutine.
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self.check_response(
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response,
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middleware_method,
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name="%s.process_template_response"
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% (middleware_method.__self__.__class__.__name__,),
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)
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try:
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if iscoroutinefunction(response.render):
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response = await response.render()
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else:
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response = await sync_to_async(
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response.render, thread_sensitive=True
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)()
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except Exception as e:
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response = await sync_to_async(
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self.process_exception_by_middleware,
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thread_sensitive=True,
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)(e, request)
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if response is None:
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raise
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# Make sure the response is not a coroutine
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if asyncio.iscoroutine(response):
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raise RuntimeError("Response is still a coroutine.")
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return response
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def resolve_request(self, request):
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"""
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Retrieve/set the urlconf for the request. Return the view resolved,
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with its args and kwargs.
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"""
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# Work out the resolver.
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if hasattr(request, "urlconf"):
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urlconf = request.urlconf
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set_urlconf(urlconf)
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resolver = get_resolver(urlconf)
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else:
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resolver = get_resolver()
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# Resolve the view, and assign the match object back to the request.
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resolver_match = resolver.resolve(request.path_info)
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request.resolver_match = resolver_match
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return resolver_match
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def check_response(self, response, callback, name=None):
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"""
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Raise an error if the view returned None or an uncalled coroutine.
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"""
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if not (response is None or asyncio.iscoroutine(response)):
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return
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if not name:
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if isinstance(callback, types.FunctionType): # FBV
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name = "The view %s.%s" % (callback.__module__, callback.__name__)
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else: # CBV
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name = "The view %s.%s.__call__" % (
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callback.__module__,
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callback.__class__.__name__,
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)
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if response is None:
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raise ValueError(
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"%s didn't return an HttpResponse object. It returned None "
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"instead." % name
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)
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elif asyncio.iscoroutine(response):
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raise ValueError(
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"%s didn't return an HttpResponse object. It returned an "
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"unawaited coroutine instead. You may need to add an 'await' "
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"into your view." % name
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)
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# Other utility methods.
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def make_view_atomic(self, view):
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non_atomic_requests = getattr(view, "_non_atomic_requests", set())
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for alias, settings_dict in connections.settings.items():
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if settings_dict["ATOMIC_REQUESTS"] and alias not in non_atomic_requests:
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if iscoroutinefunction(view):
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raise RuntimeError(
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"You cannot use ATOMIC_REQUESTS with async views."
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)
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view = transaction.atomic(using=alias)(view)
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return view
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def process_exception_by_middleware(self, exception, request):
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"""
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Pass the exception to the exception middleware. If no middleware
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return a response for this exception, return None.
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"""
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for middleware_method in self._exception_middleware:
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response = middleware_method(request, exception)
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if response:
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return response
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return None
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def reset_urlconf(sender, **kwargs):
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"""Reset the URLconf after each request is finished."""
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set_urlconf(None)
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request_finished.connect(reset_urlconf)
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