【Django】handler实现

 handler = self.get_handler(*args, **options)

def get_handler(self, *args, **options):
    """Return the default WSGI handler for the runner."""
    return get_internal_wsgi_application()

from django.core.servers.basehttp import WSGIServer, get_internal_wsgi_application

def get_internal_wsgi_application():
    """
    Load and return the WSGI application as configured by the user in
    ``settings.WSGI_APPLICATION``. With the default ``startproject`` layout,
    this will be the ``application`` object in ``projectname/wsgi.py``.

    This function, and the ``WSGI_APPLICATION`` setting itself, are only useful
    for Django's internal server (runserver); external WSGI servers should just
    be configured to point to the correct application object directly.

    If settings.WSGI_APPLICATION is not set (is ``None``), return
    whatever ``django.core.wsgi.get_wsgi_application`` returns.
    """
    from django.conf import settings

    app_path = getattr(settings, "WSGI_APPLICATION")
    if app_path is None:
        return get_wsgi_application()

    try:
        return import_string(app_path)
    except ImportError as err:
        raise ImproperlyConfigured(
            "WSGI application '%s' could not be loaded; "
            "Error importing module." % app_path
        ) from err

WSGI_APPLICATION = 'myproject.wsgi.application'

return import_string(app_path)

import os

from django.core.wsgi import get_wsgi_application

os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'myproject.settings')

application = get_wsgi_application()

from django.core.handlers.wsgi import WSGIHandler

def get_wsgi_application():
    """
    The public interface to Django's WSGI support. Return a WSGI callable.

    Avoids making django.core.handlers.WSGIHandler a public API, in case the
    internal WSGI implementation changes or moves in the future.
    """
    django.setup(set_prefix=False)
    return WSGIHandler()

class WSGIHandler(base.BaseHandler):
    request_class = WSGIRequest

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.load_middleware()

    def __call__(self, environ, start_response):
        set_script_prefix(get_script_name(environ))
        signals.request_started.send(sender=self.__class__, environ=environ)
        request = self.request_class(environ)
        response = self.get_response(request)

        response._handler_class = self.__class__

        status = "%d %s" % (response.status_code, response.reason_phrase)
        response_headers = [
            *response.items(),
            *(("Set-Cookie", c.OutputString()) for c in response.cookies.values()),
        ]
        start_response(status, response_headers)
        if getattr(response, "file_to_stream", None) is not None and environ.get(
            "wsgi.file_wrapper"
        ):
            # If `wsgi.file_wrapper` is used the WSGI server does not call
            # .close on the response, but on the file wrapper. Patch it to use
            # response.close instead which takes care of closing all files.
            response.file_to_stream.close = response.close
            response = environ["wsgi.file_wrapper"](
                response.file_to_stream, response.block_size
            )
        return response

class BaseHandler:
    _view_middleware = None
    _template_response_middleware = None
    _exception_middleware = None
    _middleware_chain = None

    def load_middleware(self, is_async=False):
        """
        Populate middleware lists from settings.MIDDLEWARE.

        Must be called after the environment is fixed (see __call__ in
        subclasses).
        """
        self._view_middleware = []
        self._template_response_middleware = []
        self._exception_middleware = []

        get_response = self._get_response_async if is_async else self._get_response
        handler = convert_exception_to_response(get_response)
        handler_is_async = is_async
        for middleware_path in reversed(settings.MIDDLEWARE):
            middleware = import_string(middleware_path)
            middleware_can_sync = getattr(middleware, "sync_capable", True)
            middleware_can_async = getattr(middleware, "async_capable", False)
            if not middleware_can_sync and not middleware_can_async:
                raise RuntimeError(
                    "Middleware %s must have at least one of "
                    "sync_capable/async_capable set to True." % middleware_path
                )
            elif not handler_is_async and middleware_can_sync:
                middleware_is_async = False
            else:
                middleware_is_async = middleware_can_async
            try:
                # Adapt handler, if needed.
                adapted_handler = self.adapt_method_mode(
                    middleware_is_async,
                    handler,
                    handler_is_async,
                    debug=settings.DEBUG,
                    name="middleware %s" % middleware_path,
                )
                mw_instance = middleware(adapted_handler)
            except MiddlewareNotUsed as exc:
                if settings.DEBUG:
                    if str(exc):
                        logger.debug("MiddlewareNotUsed(%r): %s", middleware_path, exc)
                    else:
                        logger.debug("MiddlewareNotUsed: %r", middleware_path)
                continue
            else:
                handler = adapted_handler

            if mw_instance is None:
                raise ImproperlyConfigured(
                    "Middleware factory %s returned None." % middleware_path
                )

            if hasattr(mw_instance, "process_view"):
                self._view_middleware.insert(
                    0,
                    self.adapt_method_mode(is_async, mw_instance.process_view),
                )
            if hasattr(mw_instance, "process_template_response"):
                self._template_response_middleware.append(
                    self.adapt_method_mode(
                        is_async, mw_instance.process_template_response
                    ),
                )
            if hasattr(mw_instance, "process_exception"):
                # The exception-handling stack is still always synchronous for
                # now, so adapt that way.
                self._exception_middleware.append(
                    self.adapt_method_mode(False, mw_instance.process_exception),
                )

            handler = convert_exception_to_response(mw_instance)
            handler_is_async = middleware_is_async

        # Adapt the top of the stack, if needed.
        handler = self.adapt_method_mode(is_async, handler, handler_is_async)
        # We only assign to this when initialization is complete as it is used
        # as a flag for initialization being complete.
        self._middleware_chain = handler

self._view_middleware = []
self._template_response_middleware = []
self._exception_middleware = []

def convert_exception_to_response(get_response):
    """
    Wrap the given get_response callable in exception-to-response conversion.

    All exceptions will be converted. All known 4xx exceptions (Http404,
    PermissionDenied, MultiPartParserError, SuspiciousOperation) will be
    converted to the appropriate response, and all other exceptions will be
    converted to 500 responses.

    This decorator is automatically applied to all middleware to ensure that
    no middleware leaks an exception and that the next middleware in the stack
    can rely on getting a response instead of an exception.
    """
    if iscoroutinefunction(get_response):

        @wraps(get_response)
        async def inner(request):
            try:
                response = await get_response(request)
            except Exception as exc:
                response = await sync_to_async(
                    response_for_exception, thread_sensitive=False
                )(request, exc)
            return response

        return inner
    else:

        @wraps(get_response)
        def inner(request):
            try:
                response = get_response(request)
            except Exception as exc:
                response = response_for_exception(request, exc)
            return response

        return inner

        for middleware_path in reversed(settings.MIDDLEWARE):
            middleware = import_string(middleware_path)
            middleware_can_sync = getattr(middleware, "sync_capable", True)
            middleware_can_async = getattr(middleware, "async_capable", False)
            if not middleware_can_sync and not middleware_can_async:
                raise RuntimeError(
                    "Middleware %s must have at least one of "
                    "sync_capable/async_capable set to True." % middleware_path
                )
            elif not handler_is_async and middleware_can_sync:
                middleware_is_async = False
            else:
                middleware_is_async = middleware_can_async
            try:
                # Adapt handler, if needed.
                adapted_handler = self.adapt_method_mode(
                    middleware_is_async,
                    handler,
                    handler_is_async,
                    debug=settings.DEBUG,
                    name="middleware %s" % middleware_path,
                )
                mw_instance = middleware(adapted_handler)
            except MiddlewareNotUsed as exc:
                if settings.DEBUG:
                    if str(exc):
                        logger.debug("MiddlewareNotUsed(%r): %s", middleware_path, exc)
                    else:
                        logger.debug("MiddlewareNotUsed: %r", middleware_path)
                continue
            else:
                handler = adapted_handler

            if mw_instance is None:
                raise ImproperlyConfigured(
                    "Middleware factory %s returned None." % middleware_path
                )

            if hasattr(mw_instance, "process_view"):
                self._view_middleware.insert(
                    0,
                    self.adapt_method_mode(is_async, mw_instance.process_view),
                )
            if hasattr(mw_instance, "process_template_response"):
                self._template_response_middleware.append(
                    self.adapt_method_mode(
                        is_async, mw_instance.process_template_response
                    ),
                )
            if hasattr(mw_instance, "process_exception"):
                # The exception-handling stack is still always synchronous for
                # now, so adapt that way.
                self._exception_middleware.append(
                    self.adapt_method_mode(False, mw_instance.process_exception),
                )

            handler = convert_exception_to_response(mw_instance)
            handler_is_async = middleware_is_async

# Adapt the top of the stack, if needed.
        handler = self.adapt_method_mode(is_async, handler, handler_is_async)
        # We only assign to this when initialization is complete as it is used
        # as a flag for initialization being complete.
        self._middleware_chain = handler

application(environ,start_response)

    def __call__(self, environ, start_response):
        set_script_prefix(get_script_name(environ))
        signals.request_started.send(sender=self.__class__, environ=environ)
        request = self.request_class(environ)
        response = self.get_response(request)

        response._handler_class = self.__class__

        status = "%d %s" % (response.status_code, response.reason_phrase)
        response_headers = [
            *response.items(),
            *(("Set-Cookie", c.OutputString()) for c in response.cookies.values()),
        ]
        start_response(status, response_headers)
        if getattr(response, "file_to_stream", None) is not None and environ.get(
            "wsgi.file_wrapper"
        ):
            # If `wsgi.file_wrapper` is used the WSGI server does not call
            # .close on the response, but on the file wrapper. Patch it to use
            # response.close instead which takes care of closing all files.
            response.file_to_stream.close = response.close
            response = environ["wsgi.file_wrapper"](
                response.file_to_stream, response.block_size
            )
        return response

status要求:
*至少4个字符
*前3个必须是数字
*数字后面需要空格
*返回的response需要是一个可迭代对象
*environ,start_response是WSGI传给这个函数,我们只要专注修改

def get_script_name(environ):
    """
    Return the equivalent of the HTTP request's SCRIPT_NAME environment
    variable. If Apache mod_rewrite is used, return what would have been
    the script name prior to any rewriting (so it's the script name as seen
    from the client's perspective), unless the FORCE_SCRIPT_NAME setting is
    set (to anything).
    """
    if settings.FORCE_SCRIPT_NAME is not None:
        return settings.FORCE_SCRIPT_NAME

    # If Apache's mod_rewrite had a whack at the URL, Apache set either
    # SCRIPT_URL or REDIRECT_URL to the full resource URL before applying any
    # rewrites. Unfortunately not every web server (lighttpd!) passes this
    # information through all the time, so FORCE_SCRIPT_NAME, above, is still
    # needed.
    script_url = get_bytes_from_wsgi(environ, "SCRIPT_URL", "") or get_bytes_from_wsgi(
        environ, "REDIRECT_URL", ""
    )

    if script_url:
        if b"//" in script_url:
            # mod_wsgi squashes multiple successive slashes in PATH_INFO,
            # do the same with script_url before manipulating paths (#17133).
            script_url = _slashes_re.sub(b"/", script_url)
        path_info = get_bytes_from_wsgi(environ, "PATH_INFO", "")
        script_name = script_url.removesuffix(path_info)
    else:
        script_name = get_bytes_from_wsgi(environ, "SCRIPT_NAME", "")

    return script_name.decode()

def set_script_prefix(prefix):
    """
    Set the script prefix for the current thread.
    """
    if not prefix.endswith("/"):
        prefix += "/"
    _prefixes.value = prefix

 signals.request_started.send(sender=self.__class__, environ=environ)

from django.dispatch import Signal

request_started = Signal()
request_finished = Signal()
got_request_exception = Signal()
setting_changed = Signal()

class Signal:
    """
    Base class for all signals

    Internal attributes:

        receivers:
            [
                (
                    (id(receiver), id(sender)),
                    ref(receiver),
                    ref(sender),
                    is_async,
                )
            ]
        sender_receivers_cache:
            WeakKeyDictionary[sender, list[receiver]]
    """

    def __init__(self, use_caching=False):
        """
        Create a new signal.
        """
        self.receivers = []
        self.lock = threading.Lock()
        self.use_caching = use_caching
        # For convenience we create empty caches even if they are not used.
        # A note about caching: if use_caching is defined, then for each
        # distinct sender we cache the receivers that sender has in
        # 'sender_receivers_cache'. The cache is cleaned when .connect() or
        # .disconnect() is called and populated on send().
        self.sender_receivers_cache = weakref.WeakKeyDictionary() if use_caching else {}
        self._dead_receivers = False

 signals.request_started.send(sender=self.__class__, environ=environ)

    def send(self, sender, **named):
        """
        Send signal from sender to all connected receivers.

        If any receiver raises an error, the error propagates back through
        send, terminating the dispatch loop. So it's possible that all
        receivers won't be called if an error is raised.

        If any receivers are asynchronous, they are called after all the
        synchronous receivers via a single call to async_to_sync(). They are
        also executed concurrently with asyncio.TaskGroup().

        Arguments:

            sender
                The sender of the signal. Either a specific object or None.

            named
                Named arguments which will be passed to receivers.

        Return a list of tuple pairs [(receiver, response), ... ].
        """
        if (
            not self.receivers
            or self.sender_receivers_cache.get(sender) is NO_RECEIVERS
        ):
            return []
        responses = []
        sync_receivers, async_receivers = self._live_receivers(sender)
        for receiver in sync_receivers:
            response = receiver(signal=self, sender=sender, **named)
            responses.append((receiver, response))
        if async_receivers:

            async def asend():
                async_responses = await _run_parallel(
                    *(
                        receiver(signal=self, sender=sender, **named)
                        for receiver in async_receivers
                    )
                )
                return zip(async_receivers, async_responses)

            responses.extend(async_to_sync(asend)())
        return responses

        if (
            not self.receivers
            or self.sender_receivers_cache.get(sender) is NO_RECEIVERS
        ):
            return []

 responses = []

sync_receivers, async_receivers = self._live_receivers(sender)

request = self.request_class(environ)

class WSGIHandler(base.BaseHandler):
    request_class = WSGIRequest

class WSGIRequest(HttpRequest):
    def __init__(self, environ):
        script_name = get_script_name(environ)
        # If PATH_INFO is empty (e.g. accessing the SCRIPT_NAME URL without a
        # trailing slash), operate as if '/' was requested.
        path_info = get_path_info(environ) or "/"
        self.environ = environ
        self.path_info = path_info
        # be careful to only replace the first slash in the path because of
        # http://test/something and http://test//something being different as
        # stated in RFC 3986.
        self.path = "%s/%s" % (script_name.rstrip("/"), path_info.replace("/", "", 1))
        self.META = environ
        self.META["PATH_INFO"] = path_info
        self.META["SCRIPT_NAME"] = script_name
        self.method = environ["REQUEST_METHOD"].upper()
        # Set content_type, content_params, and encoding.
        self._set_content_type_params(environ)
        try:
            content_length = int(environ.get("CONTENT_LENGTH"))
        except (ValueError, TypeError):
            content_length = 0
        self._stream = LimitedStream(self.environ["wsgi.input"], content_length)
        self._read_started = False
        self.resolver_match = None

response = self.get_response(request)

    def get_response(self, request):
        """Return an HttpResponse object for the given HttpRequest."""
        # Setup default url resolver for this thread
        set_urlconf(settings.ROOT_URLCONF)
        response = self._middleware_chain(request)
        response._resource_closers.append(request.close)
        if response.status_code >= 400:
            log_response(
                "%s: %s",
                response.reason_phrase,
                request.path,
                response=response,
                request=request,
            )
        return response

set_urlconf(settings.ROOT_URLCONF)

def set_urlconf(urlconf_name):
    """
    Set the URLconf for the current thread or asyncio task (overriding the
    default one in settings). If urlconf_name is None, revert back to the
    default.
    """
    if urlconf_name:
        _urlconfs.value = urlconf_name
    else:
        if hasattr(_urlconfs, "value"):
            del _urlconfs.value

import re

from django.conf import settings
from django.http import HttpResponsePermanentRedirect
from django.utils.deprecation import MiddlewareMixin


class SecurityMiddleware(MiddlewareMixin):
    def __init__(self, get_response):
        super().__init__(get_response)
        self.sts_seconds = settings.SECURE_HSTS_SECONDS
        self.sts_include_subdomains = settings.SECURE_HSTS_INCLUDE_SUBDOMAINS
        self.sts_preload = settings.SECURE_HSTS_PRELOAD
        self.content_type_nosniff = settings.SECURE_CONTENT_TYPE_NOSNIFF
        self.redirect = settings.SECURE_SSL_REDIRECT
        self.redirect_host = settings.SECURE_SSL_HOST
        self.redirect_exempt = [re.compile(r) for r in settings.SECURE_REDIRECT_EXEMPT]
        self.referrer_policy = settings.SECURE_REFERRER_POLICY
        self.cross_origin_opener_policy = settings.SECURE_CROSS_ORIGIN_OPENER_POLICY

class MiddlewareMixin:
    sync_capable = True
    async_capable = True

    def __init__(self, get_response):
        if get_response is None:
            raise ValueError("get_response must be provided.")
        self.get_response = get_response
        # If get_response is a coroutine function, turns us into async mode so
        # a thread is not consumed during a whole request.
        self.async_mode = iscoroutinefunction(self.get_response)
        if self.async_mode:
            # Mark the class as async-capable, but do the actual switch inside
            # __call__ to avoid swapping out dunder methods.
            markcoroutinefunction(self)
        super().__init__()

sync_capable = True
async_capable = True

self.get_response = get_response

self.async_mode = iscoroutinefunction(self.get_response)
        if self.async_mode:
            # Mark the class as async-capable, but do the actual switch inside
            # __call__ to avoid swapping out dunder methods.
            markcoroutinefunction(self)
        super().__init__()

    def __call__(self, request):
        # Exit out to async mode, if needed
        if self.async_mode:
            return self.__acall__(request)
        response = None
        if hasattr(self, "process_request"):
            response = self.process_request(request)
        response = response or self.get_response(request)
        if hasattr(self, "process_response"):
            response = self.process_response(request, response)
        return response

class BaseHandler:
    _view_middleware = None
    _template_response_middleware = None
    _exception_middleware = None
    _middleware_chain = None

    def load_middleware(self, is_async=False):
        """
        Populate middleware lists from settings.MIDDLEWARE.

        Must be called after the environment is fixed (see __call__ in
        subclasses).
        """
        self._view_middleware = []
        self._template_response_middleware = []
        self._exception_middleware = []

        get_response = self._get_response_async if is_async else self._get_response

    def _get_response(self, request):
        """
        Resolve and call the view, then apply view, exception, and
        template_response middleware. This method is everything that happens
        inside the request/response middleware.
        """
        response = None
        callback, callback_args, callback_kwargs = self.resolve_request(request)

        # Apply view middleware
        for middleware_method in self._view_middleware:
            response = middleware_method(
                request, callback, callback_args, callback_kwargs
            )
            if response:
                break

        if response is None:
            wrapped_callback = self.make_view_atomic(callback)
            # If it is an asynchronous view, run it in a subthread.
            if iscoroutinefunction(wrapped_callback):
                wrapped_callback = async_to_sync(wrapped_callback)
            try:
                response = wrapped_callback(request, *callback_args, **callback_kwargs)
            except Exception as e:
                response = self.process_exception_by_middleware(e, request)
                if response is None:
                    raise

        # Complain if the view returned None (a common error).
        self.check_response(response, callback)

        # If the response supports deferred rendering, apply template
        # response middleware and then render the response
        if hasattr(response, "render") and callable(response.render):
            for middleware_method in self._template_response_middleware:
                response = middleware_method(request, response)
                # Complain if the template response middleware returned None
                # (a common error).
                self.check_response(
                    response,
                    middleware_method,
                    name="%s.process_template_response"
                    % (middleware_method.__self__.__class__.__name__,),
                )
            try:
                response = response.render()
            except Exception as e:
                response = self.process_exception_by_middleware(e, request)
                if response is None:
                    raise

        return response

    def resolve_request(self, request):
        """
        Retrieve/set the urlconf for the request. Return the view resolved,
        with its args and kwargs.
        """
        # Work out the resolver.
        if hasattr(request, "urlconf"):
            urlconf = request.urlconf
            set_urlconf(urlconf)
            resolver = get_resolver(urlconf)
        else:
            resolver = get_resolver()
        # Resolve the view, and assign the match object back to the request.
        resolver_match = resolver.resolve(request.path_info)
        request.resolver_match = resolver_match
        return resolver_match

resolver = get_resolver()

def get_resolver(urlconf=None):
    if urlconf is None:
        urlconf = settings.ROOT_URLCONF
    return _get_cached_resolver(urlconf)

@functools.cache
def _get_cached_resolver(urlconf=None):
    return URLResolver(RegexPattern(r"^/"), urlconf)

class URLResolver:
    def __init__(
        self, pattern, urlconf_name, default_kwargs=None, app_name=None, namespace=None
    ):
        self.pattern = pattern
        # urlconf_name is the dotted Python path to the module defining
        # urlpatterns. It may also be an object with an urlpatterns attribute
        # or urlpatterns itself.
        self.urlconf_name = urlconf_name
        self.callback = None
        self.default_kwargs = default_kwargs or {}
        self.namespace = namespace
        self.app_name = app_name
        self._reverse_dict = {}
        self._namespace_dict = {}
        self._app_dict = {}
        # set of dotted paths to all functions and classes that are used in
        # urlpatterns
        self._callback_strs = set()
        self._populated = False
        self._local = Local()

class RegexPattern(CheckURLMixin):
    regex = LocaleRegexDescriptor()

    def __init__(self, regex, name=None, is_endpoint=False):
        self._regex = regex
        self._regex_dict = {}
        self._is_endpoint = is_endpoint
        self.name = name
        self.converters = {}

resolver_match = resolver.resolve(request.path_info)

    def resolve(self, path):
        path = str(path)  # path may be a reverse_lazy object
        tried = []
        match = self.pattern.match(path)
        if match:
            new_path, args, kwargs = match
            for pattern in self.url_patterns:
                try:
                    sub_match = pattern.resolve(new_path)
                except Resolver404 as e:
                    self._extend_tried(tried, pattern, e.args[0].get("tried"))
                else:
                    if sub_match:
                        # Merge captured arguments in match with submatch
                        sub_match_dict = {**kwargs, **self.default_kwargs}
                        # Update the sub_match_dict with the kwargs from the
                        # sub_match.
                        sub_match_dict.update(sub_match.kwargs)
                        # If there are *any* named groups, ignore all non-named
                        # groups. Otherwise, pass all non-named arguments as
                        # positional arguments.
                        sub_match_args = sub_match.args
                        if not sub_match_dict:
                            sub_match_args = args + sub_match.args
                        current_route = (
                            ""
                            if isinstance(pattern, URLPattern)
                            else str(pattern.pattern)
                        )
                        self._extend_tried(tried, pattern, sub_match.tried)
                        return ResolverMatch(
                            sub_match.func,
                            sub_match_args,
                            sub_match_dict,
                            sub_match.url_name,
                            [self.app_name, *sub_match.app_names],
                            [self.namespace, *sub_match.namespaces],
                            self._join_route(current_route, sub_match.route),
                            tried,
                            captured_kwargs=sub_match.captured_kwargs,
                            extra_kwargs={
                                **self.default_kwargs,
                                **sub_match.extra_kwargs,
                            },
                        )
                    tried.append([pattern])
            raise Resolver404({"tried": tried, "path": new_path})
        raise Resolver404({"path": path})

return ResolverMatch(
                            sub_match.func,
                            sub_match_args,
                            sub_match_dict,
                            sub_match.url_name,
                            [self.app_name, *sub_match.app_names],
                            [self.namespace, *sub_match.namespaces],
                            self._join_route(current_route, sub_match.route),
                            tried,
                            captured_kwargs=sub_match.captured_kwargs,
                            extra_kwargs={
                                **self.default_kwargs,
                                **sub_match.extra_kwargs,
                            },
                        )

 callback, callback_args, callback_kwargs = self.resolve_request(request)

 def __getitem__(self, index):
    return (self.func, self.args, self.kwargs)[index]

 for middleware_method in self._view_middleware:
            response = middleware_method(
                request, callback, callback_args, callback_kwargs
            )
            if response:
                break

        if response is None:
            wrapped_callback = self.make_view_atomic(callback)
            # If it is an asynchronous view, run it in a subthread.
            if iscoroutinefunction(wrapped_callback):
                wrapped_callback = async_to_sync(wrapped_callback)
            try:
                response = wrapped_callback(request, *callback_args, **callback_kwargs)
            except Exception as e:
                response = self.process_exception_by_middleware(e, request)
                if response is None:
                    raise

    def make_view_atomic(self, view):
        non_atomic_requests = getattr(view, "_non_atomic_requests", set())
        for alias, settings_dict in connections.settings.items():
            if settings_dict["ATOMIC_REQUESTS"] and alias not in non_atomic_requests:
                if iscoroutinefunction(view):
                    raise RuntimeError(
                        "You cannot use ATOMIC_REQUESTS with async views."
                    )
                view = transaction.atomic(using=alias)(view)
        return view

self.check_response(response, callback)

    def check_response(self, response, callback, name=None):
        """
        Raise an error if the view returned None or an uncalled coroutine.
        """
        if not (response is None or asyncio.iscoroutine(response)):
            return
        if not name:
            if isinstance(callback, types.FunctionType):  # FBV
                name = "The view %s.%s" % (callback.__module__, callback.__name__)
            else:  # CBV
                name = "The view %s.%s.__call__" % (
                    callback.__module__,
                    callback.__class__.__name__,
                )
        if response is None:
            raise ValueError(
                "%s didn't return an HttpResponse object. It returned None "
                "instead." % name
            )
        elif asyncio.iscoroutine(response):
            raise ValueError(
                "%s didn't return an HttpResponse object. It returned an "
                "unawaited coroutine instead. You may need to add an 'await' "
                "into your view." % name
            )

        if hasattr(response, "render") and callable(response.render):
            for middleware_method in self._template_response_middleware:
                response = middleware_method(request, response)
                # Complain if the template response middleware returned None
                # (a common error).
                self.check_response(
                    response,
                    middleware_method,
                    name="%s.process_template_response"
                    % (middleware_method.__self__.__class__.__name__,),
                )
            try:
                response = response.render()
            except Exception as e:
                response = self.process_exception_by_middleware(e, request)
                if response is None:
                    raise

 def get_response(self, request):
        """Return an HttpResponse object for the given HttpRequest."""
        # Setup default url resolver for this thread
        set_urlconf(settings.ROOT_URLCONF)
        response = self._middleware_chain(request)
        response._resource_closers.append(request.close)
        if response.status_code >= 400:
            log_response(
                "%s: %s",
                response.reason_phrase,
                request.path,
                response=response,
                request=request,
            )
        return response

 def __call__(self, environ, start_response):
        set_script_prefix(get_script_name(environ))
        signals.request_started.send(sender=self.__class__, environ=environ)
        request = self.request_class(environ)
        response = self.get_response(request)

        response._handler_class = self.__class__

        status = "%d %s" % (response.status_code, response.reason_phrase)
        response_headers = [
            *response.items(),
            *(("Set-Cookie", c.OutputString()) for c in response.cookies.values()),
        ]
        start_response(status, response_headers)
        if getattr(response, "file_to_stream", None) is not None and environ.get(
            "wsgi.file_wrapper"
        ):
            # If `wsgi.file_wrapper` is used the WSGI server does not call
            # .close on the response, but on the file wrapper. Patch it to use
            # response.close instead which takes care of closing all files.
            response.file_to_stream.close = response.close
            response = environ["wsgi.file_wrapper"](
                response.file_to_stream, response.block_size
            )
        return response

 response._handler_class = self.__class__

status = "%d %s" % (response.status_code, response.reason_phrase)

 response_headers = [
            *response.items(),
            *(("Set-Cookie", c.OutputString()) for c in response.cookies.values()),
        ]

start_response(status, response_headers)

  if getattr(response, "file_to_stream", None) is not None and environ.get(
            "wsgi.file_wrapper"
        ):
            # If `wsgi.file_wrapper` is used the WSGI server does not call
            # .close on the response, but on the file wrapper. Patch it to use
            # response.close instead which takes care of closing all files.
            response.file_to_stream.close = response.close
            response = environ["wsgi.file_wrapper"](
                response.file_to_stream, response.block_size
            )

response.file_to_stream.close = response.close

response = environ["wsgi.file_wrapper"](
    response.file_to_stream, response.block_size
)