【Django】启动过程

conda create -n django-test  python=3.12

conda activate django-test

pip install django
或者 pip .  install django=="指定版本"

def main():
    """Run administrative tasks."""
    os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'myproject.settings')
    try:
        from django.core.management import execute_from_command_line
    except ImportError as exc:
        raise ImportError(
            "Couldn't import Django. Are you sure it's installed and "
            "available on your PYTHONPATH environment variable? Did you "
            "forget to activate a virtual environment?"
        ) from exc
    execute_from_command_line(sys.argv)


if __name__ == '__main__':
    main()

sys.argv: ['manage.py', 'runserver', '8000']

def execute_from_command_line(argv=None):
    """Run a ManagementUtility."""
    utility = ManagementUtility(argv)
    utility.execute()

class ManagementUtility:
    def __init__(self, argv=None):
        self.argv = argv or sys.argv[:]
        self.prog_name = os.path.basename(self.argv[0])
        if self.prog_name == "__main__.py":
            self.prog_name = "python -m django"
        self.settings_exception = None

class ManagementUtility:
    ...
    def execute(self):
        """
        Given the command-line arguments, figure out which subcommand is being
        run, create a parser appropriate to that command, and run it.
        """
        try:
            subcommand = self.argv[1]
        except IndexError:
            subcommand = "help"  # Display help if no arguments were given.

        # Preprocess options to extract --settings and --pythonpath.
        # These options could affect the commands that are available, so they
        # must be processed early.
        parser = CommandParser(
            prog=self.prog_name,
            usage="%(prog)s subcommand [options] [args]",
            add_help=False,
            allow_abbrev=False,
        )
        parser.add_argument("--settings")
        parser.add_argument("--pythonpath")
        parser.add_argument("args", nargs="*")  # catch-all
        try:
            options, args = parser.parse_known_args(self.argv[2:])
            handle_default_options(options)
        except CommandError:
            pass  # Ignore any option errors at this point.

        try:
            settings.INSTALLED_APPS
        except ImproperlyConfigured as exc:
            self.settings_exception = exc
        except ImportError as exc:
            self.settings_exception = exc

        if settings.configured:
            # Start the auto-reloading dev server even if the code is broken.
            # The hardcoded condition is a code smell but we can't rely on a
            # flag on the command class because we haven't located it yet.
            if subcommand == "runserver" and "--noreload" not in self.argv:
                try:
                    autoreload.check_errors(django.setup)()
                except Exception:
                    # The exception will be raised later in the child process
                    # started by the autoreloader. Pretend it didn't happen by
                    # loading an empty list of applications.
                    apps.all_models = defaultdict(dict)
                    apps.app_configs = {}
                    apps.apps_ready = apps.models_ready = apps.ready = True

                    # Remove options not compatible with the built-in runserver
                    # (e.g. options for the contrib.staticfiles' runserver).
                    # Changes here require manually testing as described in
                    # #27522.
                    _parser = self.fetch_command("runserver").create_parser(
                        "django", "runserver"
                    )
                    _options, _args = _parser.parse_known_args(self.argv[2:])
                    for _arg in _args:
                        self.argv.remove(_arg)

            # In all other cases, django.setup() is required to succeed.
            else:
                django.setup()

        self.autocomplete()

        if subcommand == "help":
            if "--commands" in args:
                sys.stdout.write(self.main_help_text(commands_only=True) + "\n")
            elif not options.args:
                sys.stdout.write(self.main_help_text() + "\n")
            else:
                self.fetch_command(options.args[0]).print_help(
                    self.prog_name, options.args[0]
                )
        # Special-cases: We want 'django-admin --version' and
        # 'django-admin --help' to work, for backwards compatibility.
        elif subcommand == "version" or self.argv[1:] == ["--version"]:
            sys.stdout.write(django.get_version() + "\n")
        elif self.argv[1:] in (["--help"], ["-h"]):
            sys.stdout.write(self.main_help_text() + "\n")
        else:
            self.fetch_command(subcommand).run_from_argv(self.argv)

 try:
    subcommand = self.argv[1]
 except IndexError:
    subcommand = "help"  # Display help if no arguments were given.

parser = CommandParser(
            prog=self.prog_name,
            usage="%(prog)s subcommand [options] [args]",
            add_help=False,
            allow_abbrev=False,
        )
        parser.add_argument("--settings")
        parser.add_argument("--pythonpath")
        parser.add_argument("args", nargs="*")  # catch-all

  try:
    options, args = parser.parse_known_args(self.argv[2:])
    handle_default_options(options)
  except CommandError:
        pass  # Ignore any option errors at this point.

from django.core.management.base import (
    ...
    handle_default_options,
)

def handle_default_options(options):
    """
    Include any default options that all commands should accept here
    so that ManagementUtility can handle them before searching for
    user commands.
    """
    if options.settings:
        os.environ["DJANGO_SETTINGS_MODULE"] = options.settings
    if options.pythonpath:
        sys.path.insert(0, options.pythonpath)

 try:
    settings.INSTALLED_APPS
 except ImproperlyConfigured as exc:
    self.settings_exception = exc
except ImportError as exc:
    self.settings_exception = exc

from django.conf import settings

settings = LazySettings()

class LazySettings(LazyObject):
    """
    A lazy proxy for either global Django settings or a custom settings object.
    The user can manually configure settings prior to using them. Otherwise,
    Django uses the settings module pointed to by DJANGO_SETTINGS_MODULE.
    """

    def _setup(self, name=None):
        """
        Load the settings module pointed to by the environment variable. This
        is used the first time settings are needed, if the user hasn't
        configured settings manually.
        """
        settings_module = os.environ.get(ENVIRONMENT_VARIABLE)
        if not settings_module:
            desc = ("setting %s" % name) if name else "settings"
            raise ImproperlyConfigured(
                "Requested %s, but settings are not configured. "
                "You must either define the environment variable %s "
                "or call settings.configure() before accessing settings."
                % (desc, ENVIRONMENT_VARIABLE)
            )

        self._wrapped = Settings(settings_module)

    def __repr__(self):
        # Hardcode the class name as otherwise it yields 'Settings'.
        if self._wrapped is empty:
            return "<LazySettings [Unevaluated]>"
        return '<LazySettings "%(settings_module)s">' % {
            "settings_module": self._wrapped.SETTINGS_MODULE,
        }

    def __getattr__(self, name):
        """Return the value of a setting and cache it in self.__dict__."""
        if (_wrapped := self._wrapped) is empty:
            self._setup(name)
            _wrapped = self._wrapped
        val = getattr(_wrapped, name)

        # RemovedInDjango70Warning.
        if name in DEPRECATED_EMAIL_SETTINGS:
            if hasattr(_wrapped, "MAILERS"):
                raise AttributeError(
                    f"The {name} setting is not available when MAILERS is defined."
                )
            _show_settings_deprecation_warning(
                EMAIL_SETTING_DEPRECATED_MSG.format(name=name), RemovedInDjango70Warning
            )

        # Special case some settings which require further modification.
        # This is done here for performance reasons so the modified value is
        # cached.
        if name in {"MEDIA_URL", "STATIC_URL"} and val is not None:
            val = self._add_script_prefix(val)
        elif name == "SECRET_KEY" and not val:
            raise ImproperlyConfigured("The SECRET_KEY setting must not be empty.")

        self.__dict__[name] = val
        return val

    def __setattr__(self, name, value):
        """
        Set the value of setting. Clear all cached values if _wrapped changes
        (@override_settings does this) or clear single values when set.
        """
        if name == "_wrapped":
            self.__dict__.clear()
        else:
            self.__dict__.pop(name, None)

        # RemovedInDjango70Warning.
        if name == "SIGNED_COOKIE_LEGACY_SALT_FALLBACK":
            _show_settings_deprecation_warning(
                SIGNED_COOKIE_LEGACY_SALT_DEPRECATED_MSG,
                RemovedInDjango70Warning,
            )
        # RemovedInDjango70Warning.
        if name == "USE_BLANK_CHOICE_DASH":
            _show_settings_deprecation_warning(
                USE_BLANK_CHOICE_DASH_DEPRECATED_MSG, RemovedInDjango70Warning
            )
        # RemovedInDjango70Warning.
        if name == "MAILERS":
            # When MAILERS is set, clear any cached values of
            # deprecated settings so that __getattr__() runs again for them.
            for setting in DEPRECATED_EMAIL_SETTINGS:
                self.__dict__.pop(setting, None)
        if name in DEPRECATED_EMAIL_SETTINGS:
            _show_settings_deprecation_warning(
                EMAIL_SETTING_DEPRECATED_MSG.format(name=name), RemovedInDjango70Warning
            )

        super().__setattr__(name, value)

    def __delattr__(self, name):
        """Delete a setting and clear it from cache if needed."""
        super().__delattr__(name)
        self.__dict__.pop(name, None)

    # RemovedInDjango70Warning.
    def __dir__(self):
        attrs = super().__dir__()
        if hasattr(self._wrapped, "MAILERS"):
            # When MAILERS is defined, filter out deprecated email
            # settings that are from the global_settings defaults.
            attrs = [
                name
                for name in attrs
                if name not in DEPRECATED_EMAIL_SETTINGS
                or self._wrapped.is_overridden(name)
            ]
        return attrs

    def configure(self, default_settings=global_settings, **options):
        """
        Called to manually configure the settings. The 'default_settings'
        parameter sets where to retrieve any unspecified values from (its
        argument must support attribute access (__getattr__)).
        """
        if self._wrapped is not empty:
            raise RuntimeError("Settings already configured.")

        # RemovedInDjango70Warning.
        _check_email_settings_conflicts(options.keys())

        holder = UserSettingsHolder(default_settings)
        for name, value in options.items():
            if not name.isupper():
                raise TypeError("Setting %r must be uppercase." % name)
            setattr(holder, name, value)
        self._wrapped = holder

    @staticmethod
    def _add_script_prefix(value):
        """
        Add SCRIPT_NAME prefix to relative paths.

        Useful when the app is being served at a subpath and manually prefixing
        subpath to STATIC_URL and MEDIA_URL in settings is inconvenient.
        """
        # Don't apply prefix to absolute paths and URLs.
        if value.startswith(("http://", "https://", "/")):
            return value
        from django.urls import get_script_prefix

        return "%s%s" % (get_script_prefix(), value)

    @property
    def configured(self):
        """Return True if the settings have already been configured."""
        return self._wrapped is not empty

empty = object()

class LazyObject:
    """
    A wrapper for another class that can be used to delay instantiation of the
    wrapped class.

    By subclassing, you have the opportunity to intercept and alter the
    instantiation. If you don't need to do that, use SimpleLazyObject.
    """

    # Avoid infinite recursion when tracing __init__ (#19456).
    _wrapped = None

    def __init__(self):
        # Note: if a subclass overrides __init__(), it will likely need to
        # override __copy__() and __deepcopy__() as well.
        self._wrapped = empty

    def __getattr__(self, name):
        """Return the value of a setting and cache it in self.__dict__."""
        if (_wrapped := self._wrapped) is empty:
            self._setup(name)
            _wrapped = self._wrapped
        val = getattr(_wrapped, name)

        # RemovedInDjango70Warning.
        if name in DEPRECATED_EMAIL_SETTINGS:
            if hasattr(_wrapped, "MAILERS"):
                raise AttributeError(
                    f"The {name} setting is not available when MAILERS is defined."
                )
            _show_settings_deprecation_warning(
                EMAIL_SETTING_DEPRECATED_MSG.format(name=name), RemovedInDjango70Warning
            )

        # Special case some settings which require further modification.
        # This is done here for performance reasons so the modified value is
        # cached.
        if name in {"MEDIA_URL", "STATIC_URL"} and val is not None:
            val = self._add_script_prefix(val)
        elif name == "SECRET_KEY" and not val:
            raise ImproperlyConfigured("The SECRET_KEY setting must not be empty.")

        self.__dict__[name] = val
        return val

if (_wrapped := self._wrapped) is empty:
        self._setup(name)
        _wrapped = self._wrapped
val = getattr(_wrapped, name)

ENVIRONMENT_VARIABLE = "DJANGO_SETTINGS_MODULE"
class LazySettings(LazyObject):
    ...
    def _setup(self, name=None):
        """
        Load the settings module pointed to by the environment variable. This
        is used the first time settings are needed, if the user hasn't
        configured settings manually.
        """
        settings_module = os.environ.get(ENVIRONMENT_VARIABLE)
        if not settings_module:
            desc = ("setting %s" % name) if name else "settings"
            raise ImproperlyConfigured(
                "Requested %s, but settings are not configured. "
                "You must either define the environment variable %s "
                "or call settings.configure() before accessing settings."
                % (desc, ENVIRONMENT_VARIABLE)
            )

        self._wrapped = Settings(settings_module)

class Settings:
    def __init__(self, settings_module):
        # update this dict from global settings (but only for ALL_CAPS
        # settings)
        for setting in dir(global_settings):
            if setting.isupper():
                setattr(self, setting, getattr(global_settings, setting))

        # store the settings module in case someone later cares
        self.SETTINGS_MODULE = settings_module

        mod = importlib.import_module(self.SETTINGS_MODULE)

        tuple_settings = (
            "ALLOWED_HOSTS",
            "INSTALLED_APPS",
            "TEMPLATE_DIRS",
            "LOCALE_PATHS",
            "SECRET_KEY_FALLBACKS",
        )
        self._explicit_settings = set()
        for setting in dir(mod):
            if setting.isupper():
                setting_value = getattr(mod, setting)

                if setting in tuple_settings and not isinstance(
                    setting_value, (list, tuple)
                ):
                    raise ImproperlyConfigured(
                        "The %s setting must be a list or a tuple." % setting
                    )
                setattr(self, setting, setting_value)
                self._explicit_settings.add(setting)

        # RemovedInDjango70Warning.
        if "SIGNED_COOKIE_LEGACY_SALT_FALLBACK" in self._explicit_settings:
            warnings.warn(
                SIGNED_COOKIE_LEGACY_SALT_DEPRECATED_MSG,
                RemovedInDjango70Warning,
                skip_file_prefixes=django_file_prefixes(),
            )
        # RemovedInDjango70Warning.
        if "USE_BLANK_CHOICE_DASH" in self._explicit_settings:
            warnings.warn(
                USE_BLANK_CHOICE_DASH_DEPRECATED_MSG,
                RemovedInDjango70Warning,
                skip_file_prefixes=django_file_prefixes(),
            )
        # RemovedInDjango70Warning.
        _check_email_settings_conflicts(self._explicit_settings)
        for name in DEPRECATED_EMAIL_SETTINGS.intersection(self._explicit_settings):
            warnings.warn(
                EMAIL_SETTING_DEPRECATED_MSG.format(name=name),
                RemovedInDjango70Warning,
                skip_file_prefixes=django_file_prefixes(),
            )

        if hasattr(time, "tzset") and self.TIME_ZONE:
            # When we can, attempt to validate the timezone. If we can't find
            # this file, no check happens and it's harmless.
            zoneinfo_root = Path("/usr/share/zoneinfo")
            zone_info_file = zoneinfo_root.joinpath(*self.TIME_ZONE.split("/"))
            if zoneinfo_root.exists() and not zone_info_file.exists():
                raise ValueError("Incorrect timezone setting: %s" % self.TIME_ZONE)
            # Move the time zone info into os.environ. See ticket #2315 for why
            # we don't do this unconditionally (breaks Windows).
            os.environ["TZ"] = self.TIME_ZONE
            time.tzset()

from django.conf import global_settings

...


for setting in dir(global_settings):
    if setting.isupper():
    setattr(self, setting, getattr(global_settings, setting))

"""
DEBUG = False

# Whether the framework should propagate raw exceptions rather than catching
# them. This is useful under some testing situations and should never be used
# on a live site.
DEBUG_PROPAGATE_EXCEPTIONS = False

# People who get code error notifications. In the format
# ["email@example.com", '"Full Name" <anotheremail@example.com>']
ADMINS = []

...

    ...
 
    tuple_settings = (
    "ALLOWED_HOSTS",
    "INSTALLED_APPS",
    "TEMPLATE_DIRS",
    "LOCALE_PATHS",
    "SECRET_KEY_FALLBACKS",
    )
    self._explicit_settings = set()
    for setting in dir(mod):
        if setting.isupper():
            setting_value = getattr(mod, setting)

            if setting in tuple_settings and not isinstance(
                    setting_value, (list, tuple)
                ):
                    raise ImproperlyConfigured(
                        "The %s setting must be a list or a tuple." % setting
                    )
           setattr(self, setting, setting_value)
           self._explicit_settings.add(setting)

 if "SIGNED_COOKIE_LEGACY_SALT_FALLBACK" in self._explicit_settings:
    warnings.warn(
        SIGNED_COOKIE_LEGACY_SALT_DEPRECATED_MSG,
        RemovedInDjango70Warning,
        skip_file_prefixes=django_file_prefixes(),
    )

# RemovedInDjango70Warning.
    if "USE_BLANK_CHOICE_DASH" in self._explicit_settings:
        warnings.warn(
            USE_BLANK_CHOICE_DASH_DEPRECATED_MSG,
            RemovedInDjango70Warning,
            skip_file_prefixes=django_file_prefixes(),
        )

 # RemovedInDjango70Warning.
_check_email_settings_conflicts(self._explicit_settings)
for name in DEPRECATED_EMAIL_SETTINGS.intersection(self._explicit_settings):
    warnings.warn(
        EMAIL_SETTING_DEPRECATED_MSG.format(name=name),
        RemovedInDjango70Warning,
        skip_file_prefixes=django_file_prefixes(),
    )

        if hasattr(time, "tzset") and self.TIME_ZONE:
            # When we can, attempt to validate the timezone. If we can't find
            # this file, no check happens and it's harmless.
            zoneinfo_root = Path("/usr/share/zoneinfo")
            zone_info_file = zoneinfo_root.joinpath(*self.TIME_ZONE.split("/"))
            if zoneinfo_root.exists() and not zone_info_file.exists():
                raise ValueError("Incorrect timezone setting: %s" % self.TIME_ZONE)
            # Move the time zone info into os.environ. See ticket #2315 for why
            # we don't do this unconditionally (breaks Windows).
            os.environ["TZ"] = self.TIME_ZONE
            time.tzset()

class LazySettings(LazyObject):
    
    ...

    def __getattr__(self, name):
        """Return the value of a setting and cache it in self.__dict__."""
        if (_wrapped := self._wrapped) is empty:
            self._setup(name)
            _wrapped = self._wrapped
        val = getattr(_wrapped, name)

        # RemovedInDjango70Warning.
        if name in DEPRECATED_EMAIL_SETTINGS:
            if hasattr(_wrapped, "MAILERS"):
                raise AttributeError(
                    f"The {name} setting is not available when MAILERS is defined."
                )
            _show_settings_deprecation_warning(
                EMAIL_SETTING_DEPRECATED_MSG.format(name=name), RemovedInDjango70Warning
            )

        # Special case some settings which require further modification.
        # This is done here for performance reasons so the modified value is
        # cached.
        if name in {"MEDIA_URL", "STATIC_URL"} and val is not None:
            val = self._add_script_prefix(val)
        elif name == "SECRET_KEY" and not val:
            raise ImproperlyConfigured("The SECRET_KEY setting must not be empty.")

        self.__dict__[name] = val
        return val

INSTALLED_APPS = [
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
]

 if name in {"MEDIA_URL", "STATIC_URL"} and val is not None:
    val = self._add_script_prefix(val)
elif name == "SECRET_KEY" and not val:
    raise ImproperlyConfigured("The SECRET_KEY setting must not be empty.")

self.__dict__[name] = val
return val

    def execute(self):
        """
        Given the command-line arguments, figure out which subcommand is being
        run, create a parser appropriate to that command, and run it.
        """
        try:
            subcommand = self.argv[1]
        except IndexError:
            subcommand = "help"  # Display help if no arguments were given.

        # Preprocess options to extract --settings and --pythonpath.
        # These options could affect the commands that are available, so they
        # must be processed early.
        parser = CommandParser(
            prog=self.prog_name,
            usage="%(prog)s subcommand [options] [args]",
            add_help=False,
            allow_abbrev=False,
        )
        parser.add_argument("--settings")
        parser.add_argument("--pythonpath")
        parser.add_argument("args", nargs="*")  # catch-all
        try:
            options, args = parser.parse_known_args(self.argv[2:])
            handle_default_options(options)
        except CommandError:
            pass  # Ignore any option errors at this point.

        try:
            settings.INSTALLED_APPS
        except ImproperlyConfigured as exc:
            self.settings_exception = exc
        except ImportError as exc:
            self.settings_exception = exc

        if settings.configured:
            # Start the auto-reloading dev server even if the code is broken.
            # The hardcoded condition is a code smell but we can't rely on a
            # flag on the command class because we haven't located it yet.
            if subcommand == "runserver" and "--noreload" not in self.argv:
                try:
                    autoreload.check_errors(django.setup)()
                except Exception:
                    # The exception will be raised later in the child process
                    # started by the autoreloader. Pretend it didn't happen by
                    # loading an empty list of applications.
                    apps.all_models = defaultdict(dict)
                    apps.app_configs = {}
                    apps.apps_ready = apps.models_ready = apps.ready = True

                    # Remove options not compatible with the built-in runserver
                    # (e.g. options for the contrib.staticfiles' runserver).
                    # Changes here require manually testing as described in
                    # #27522.
                    _parser = self.fetch_command("runserver").create_parser(
                        "django", "runserver"
                    )
                    _options, _args = _parser.parse_known_args(self.argv[2:])
                    for _arg in _args:
                        self.argv.remove(_arg)

            # In all other cases, django.setup() is required to succeed.
            else:
                django.setup()

        self.autocomplete()

        if subcommand == "help":
            if "--commands" in args:
                sys.stdout.write(self.main_help_text(commands_only=True) + "\n")
            elif not options.args:
                sys.stdout.write(self.main_help_text() + "\n")
            else:
                self.fetch_command(options.args[0]).print_help(
                    self.prog_name, options.args[0]
                )
        # Special-cases: We want 'django-admin --version' and
        # 'django-admin --help' to work, for backwards compatibility.
        elif subcommand == "version" or self.argv[1:] == ["--version"]:
            sys.stdout.write(django.get_version() + "\n")
        elif self.argv[1:] in (["--help"], ["-h"]):
            sys.stdout.write(self.main_help_text() + "\n")
        else:
            self.fetch_command(subcommand).run_from_argv(self.argv)

from django.utils import autoreload
    
    ...
    
    if settings.configured:
        # Start the auto-reloading dev server even if the code is broken.
            # The hardcoded condition is a code smell but we can't rely on a
            # flag on the command class because we haven't located it yet.
        if subcommand == "runserver" and "--noreload" not in self.argv:
                try:
                    autoreload.check_errors(django.setup)()
                except Exception:
                    # The exception will be raised later in the child process
                    # started by the autoreloader. Pretend it didn't happen by
                    # loading an empty list of applications.
                    apps.all_models = defaultdict(dict)
                    apps.app_configs = {}
                    apps.apps_ready = apps.models_ready = apps.ready = True

                    # Remove options not compatible with the built-in runserver
                    # (e.g. options for the contrib.staticfiles' runserver).
                    # Changes here require manually testing as described in
                    # #27522.
                    _parser = self.fetch_command("runserver").create_parser(
                        "django", "runserver"
                    )
                    _options, _args = _parser.parse_known_args(self.argv[2:])
                    for _arg in _args:
                        self.argv.remove(_arg)

            # In all other cases, django.setup() is required to succeed.
        else:
            django.setup()

@property
def configured(self):
    """Return True if the settings have already been configured."""
    return self._wrapped is not empty

from django.utils import autoreload
            
            ...
            
            if subcommand == "runserver" and "--noreload" not in self.argv:
                try:
                    autoreload.check_errors(django.setup)()
                except Exception:
                    # The exception will be raised later in the child process
                    # started by the autoreloader. Pretend it didn't happen by
                    # loading an empty list of applications.
                    apps.all_models = defaultdict(dict)
                    apps.app_configs = {}
                    apps.apps_ready = apps.models_ready = apps.ready = True

                    # Remove options not compatible with the built-in runserver
                    # (e.g. options for the contrib.staticfiles' runserver).
                    # Changes here require manually testing as described in
                    # #27522.
                    _parser = self.fetch_command("runserver").create_parser(
                        "django", "runserver"
                    )
                    _options, _args = _parser.parse_known_args(self.argv[2:])
                    for _arg in _args:
                        self.argv.remove(_arg)

def check_errors(fn):
    @wraps(fn)
    def wrapper(*args, **kwargs):
        global _exception
        try:
            fn(*args, **kwargs)
        except Exception as e:
            _exception = sys.exc_info()

            et, ev, tb = _exception

            if getattr(ev, "filename", None) is None:
                # get the filename from the last item in the stack
                filename = traceback.extract_tb(tb)[-1][0]
            else:
                filename = ev.filename

            if filename not in _error_files:
                _error_files.append(filename)
            if _url_module_exception is not None:
                raise e from _url_module_exception

            raise e

    return wrapper

def setup(set_prefix=True):
    """
    Configure the settings (this happens as a side effect of accessing the
    first setting), configure logging and populate the app registry.
    Set the thread-local urlresolvers script prefix if `set_prefix` is True.
    """
    from django.apps import apps
    from django.conf import settings
    from django.urls import set_script_prefix
    from django.utils.log import configure_logging

    configure_logging(settings.LOGGING_CONFIG, settings.LOGGING)
    if set_prefix:
        set_script_prefix(
            "/" if settings.FORCE_SCRIPT_NAME is None else settings.FORCE_SCRIPT_NAME
        )
    apps.populate(settings.INSTALLED_APPS)

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

class Apps:

    def __init__(self, installed_apps=()):
        # installed_apps is set to None when creating the main registry
        # because it cannot be populated at that point. Other registries must
        # provide a list of installed apps and are populated immediately.
        if installed_apps is None and hasattr(sys.modules[__name__], "apps"):
            raise RuntimeError("You must supply an installed_apps argument.")

        # Mapping of app labels => model names => model classes. Every time a
        # model is imported, ModelBase.__new__ calls apps.register_model which
        # creates an entry in all_models. All imported models are registered,
        # regardless of whether they're defined in an installed application
        # and whether the registry has been populated. Since it isn't possible
        # to reimport a module safely (it could reexecute initialization code)
        # all_models is never overridden or reset.
        self.all_models = defaultdict(dict)

        # Mapping of labels to AppConfig instances for installed apps.
        self.app_configs = {}

        # Stack of app_configs. Used to store the current state in
        # set_available_apps and set_installed_apps.
        self.stored_app_configs = []

        # Whether the registry is populated.
        self.apps_ready = self.models_ready = self.ready = False
        # For the autoreloader.
        self.ready_event = threading.Event()

        # Lock for thread-safe population.
        self._lock = threading.RLock()
        self.loading = False

        # Maps ("app_label", "modelname") tuples to lists of functions to be
        # called when the corresponding model is ready. Used by this class's
        # `lazy_model_operation()` and `do_pending_operations()` methods.
        self._pending_operations = defaultdict(list)

        # Populate apps and models, unless it's the main registry.
        if installed_apps is not None:
            self.populate(installed_apps)

    def populate(self, installed_apps=None):
        """
        Load application configurations and models.

        Import each application module and then each model module.

        It is thread-safe and idempotent, but not reentrant.
        """
        if self.ready:
            return

        # populate() might be called by two threads in parallel on servers
        # that create threads before initializing the WSGI callable.
        with self._lock:
            if self.ready:
                return

            # An RLock prevents other threads from entering this section. The
            # compare and set operation below is atomic.
            if self.loading:
                # Prevent reentrant calls to avoid running AppConfig.ready()
                # methods twice.
                raise RuntimeError("populate() isn't reentrant")
            self.loading = True

            # Phase 1: initialize app configs and import app modules.
            for entry in installed_apps:
                if isinstance(entry, AppConfig):
                    app_config = entry
                else:
                    app_config = AppConfig.create(entry)
                if app_config.label in self.app_configs:
                    raise ImproperlyConfigured(
                        "Application labels aren't unique, "
                        "duplicates: %s" % app_config.label
                    )

                self.app_configs[app_config.label] = app_config
                app_config.apps = self

            # Check for duplicate app names.
            counts = Counter(
                app_config.name for app_config in self.app_configs.values()
            )
            duplicates = [name for name, count in counts.most_common() if count > 1]
            if duplicates:
                raise ImproperlyConfigured(
                    "Application names aren't unique, "
                    "duplicates: %s" % ", ".join(duplicates)
                )

            self.apps_ready = True

            # Phase 2: import models modules.
            for app_config in self.app_configs.values():
                app_config.import_models()

            self.clear_cache()

            self.models_ready = True

            # Phase 3: run ready() methods of app configs.
            for app_config in self.get_app_configs():
                app_config.ready()

            self.ready = True
            self.ready_event.set()

if self.ready:
    return

@classmethod
    def create(cls, entry):
        """
        Factory that creates an app config from an entry in INSTALLED_APPS.
        """
        # create() eventually returns app_config_class(app_name, app_module).
        app_config_class = None
        app_name = None
        app_module = None

        # If import_module succeeds, entry points to the app module.
        try:
            app_module = import_module(entry)
        except Exception:
            pass
        else:
            # If app_module has an apps submodule that defines a single
            # AppConfig subclass, use it automatically.
            # To prevent this, an AppConfig subclass can declare a class
            # variable default = False.
            # If the apps module defines more than one AppConfig subclass,
            # the default one can declare default = True.
            if module_has_submodule(app_module, APPS_MODULE_NAME):
                mod_path = "%s.%s" % (entry, APPS_MODULE_NAME)
                mod = import_module(mod_path)
                # Check if there's exactly one AppConfig candidate,
                # excluding those that explicitly define default = False.
                app_configs = [
                    (name, candidate)
                    for name, candidate in inspect.getmembers(mod, inspect.isclass)
                    if (
                        issubclass(candidate, cls)
                        and candidate is not cls
                        and getattr(candidate, "default", True)
                    )
                ]
                if len(app_configs) == 1:
                    app_config_class = app_configs[0][1]
                else:
                    # Check if there's exactly one AppConfig subclass,
                    # among those that explicitly define default = True.
                    app_configs = [
                        (name, candidate)
                        for name, candidate in app_configs
                        if getattr(candidate, "default", False)
                    ]
                    if len(app_configs) > 1:
                        candidates = [repr(name) for name, _ in app_configs]
                        raise RuntimeError(
                            "%r declares more than one default AppConfig: "
                            "%s." % (mod_path, ", ".join(candidates))
                        )
                    elif len(app_configs) == 1:
                        app_config_class = app_configs[0][1]

            # Use the default app config class if we didn't find anything.
            if app_config_class is None:
                app_config_class = cls
                app_name = entry

        # If import_string succeeds, entry is an app config class.
        if app_config_class is None:
            try:
                app_config_class = import_string(entry)
            except Exception:
                pass
        # If both import_module and import_string failed, it means that entry
        # doesn't have a valid value.
        if app_module is None and app_config_class is None:
            # If the last component of entry starts with an uppercase letter,
            # then it was likely intended to be an app config class; if not,
            # an app module. Provide a nice error message in both cases.
            mod_path, _, cls_name = entry.rpartition(".")
            if mod_path and cls_name[0].isupper():
                # We could simply re-trigger the string import exception, but
                # we're going the extra mile and providing a better error
                # message for typos in INSTALLED_APPS.
                # This may raise ImportError, which is the best exception
                # possible if the module at mod_path cannot be imported.
                mod = import_module(mod_path)
                candidates = [
                    repr(name)
                    for name, candidate in inspect.getmembers(mod, inspect.isclass)
                    if issubclass(candidate, cls) and candidate is not cls
                ]
                msg = "Module '%s' does not contain a '%s' class." % (
                    mod_path,
                    cls_name,
                )
                if candidates:
                    msg += " Choices are: %s." % ", ".join(candidates)
                raise ImportError(msg)
            else:
                # Re-trigger the module import exception.
                import_module(entry)

        # Check for obvious errors. (This check prevents duck typing, but
        # it could be removed if it became a problem in practice.)
        if not issubclass(app_config_class, AppConfig):
            raise ImproperlyConfigured("'%s' isn't a subclass of AppConfig." % entry)

        # Obtain app name here rather than in AppClass.__init__ to keep
        # all error checking for entries in INSTALLED_APPS in one place.
        if app_name is None:
            try:
                app_name = app_config_class.name
            except AttributeError:
                raise ImproperlyConfigured("'%s' must supply a name attribute." % entry)

        # Ensure app_name points to a valid module.
        try:
            app_module = import_module(app_name)
        except ImportError:
            raise ImproperlyConfigured(
                "Cannot import '%s'. Check that '%s.%s.name' is correct."
                % (
                    app_name,
                    app_config_class.__module__,
                    app_config_class.__qualname__,
                )
            )

        # Entry is a path to an app config class.
        return app_config_class(app_name, app_module)

app_config_class = None
app_name = None
app_module = None

app_module = import_module(entry)

def module_has_submodule(package, module_name):
    """See if 'module' is in 'package'."""
    try:
        package_name = package.__name__
        package_path = package.__path__
    except AttributeError:
        # package isn't a package.
        return False

    full_module_name = package_name + "." + module_name
    try:
        return importlib_find(full_module_name, package_path) is not None
    except ModuleNotFoundError:
        # When module_name is an invalid dotted path, Python raises
        # ModuleNotFoundError.
        return False

from importlib.util import find_spec as importlib_find

mod_path = "%s.%s" % (entry, APPS_MODULE_NAME)
mod = import_module(mod_path)

 app_configs = [
                    (name, candidate)
                    for name, candidate in inspect.getmembers(mod, inspect.isclass)
                    if (
                        issubclass(candidate, cls)
                        and candidate is not cls
                        and getattr(candidate, "default", True)
                    )
    ]

 return app_config_class(app_name, app_module)

class AppConfig:
    """Class representing a Django application and its configuration."""

    def __init__(self, app_name, app_module):
        # Full Python path to the application e.g. 'django.contrib.admin'.
        self.name = app_name

        # Root module for the application e.g. <module 'django.contrib.admin'
        # from 'django/contrib/admin/__init__.py'>.
        self.module = app_module

        # Reference to the Apps registry that holds this AppConfig. Set by the
        # registry when it registers the AppConfig instance.
        self.apps = None

        # The following attributes could be defined at the class level in a
        # subclass, hence the test-and-set pattern.

        # Last component of the Python path to the application e.g. 'admin'.
        # This value must be unique across a Django project.
        if not hasattr(self, "label"):
            self.label = app_name.rpartition(".")[2]
        if not self.label.isidentifier():
            raise ImproperlyConfigured(
                "The app label '%s' is not a valid Python identifier." % self.label
            )

        # Human-readable name for the application e.g. "Admin".
        if not hasattr(self, "verbose_name"):
            self.verbose_name = self.label.title()

        # Filesystem path to the application directory e.g.
        # '/path/to/django/contrib/admin'.
        if not hasattr(self, "path"):
            self.path = self._path_from_module(app_module)

        # Module containing models e.g. <module 'django.contrib.admin.models'
        # from 'django/contrib/admin/models.py'>. Set by import_models().
        # None if the application doesn't have a models module.
        self.models_module = None

        # Mapping of lowercase model names to model classes. Initially set to
        # None to prevent accidental access before import_models() runs.
        self.models = None

if not hasattr(self, "label"):
    self.label = app_name.rpartition(".")[2]

 if not self.label.isidentifier():
    raise ImproperlyConfigured(
        "The app label '%s' is not a valid Python identifier." % self.label
    )

self.verbose_name = self.label.title()

 if not hasattr(self, "path"):
    self.path = self._path_from_module(app_module)

  self.models_module = None

 self.models = None

self.models = {
    "article": <class 'myapp.models.Article'>,
    "comment": <class 'myapp.models.Comment'>,
}

from django.apps import AppConfig


class UsersConfig(AppConfig):
    name = 'users'
    label = "label123"

if app_config.label in self.app_configs:
    raise ImproperlyConfigured(
        "Application labels aren't unique, "
        "duplicates: %s" % app_config.label
    )
self.app_configs[app_config.label] = app_config

app_config.apps = self

# Check for duplicate app names.
counts = Counter(
    app_config.name for app_config in self.app_configs.values()
)
duplicates = [name for name, count in counts.most_common() if count > 1]
if duplicates:
    raise ImproperlyConfigured(
        "Application names aren't unique, "
        "duplicates: %s" % ", ".join(duplicates)
    )

self.apps_ready = True

 for app_config in self.app_configs.values():
    app_config.import_models()

    def import_models(self):
        # Dictionary of models for this app, primarily maintained in the
        # 'all_models' attribute of the Apps this AppConfig is attached to.
        self.models = self.apps.all_models[self.label]

        if module_has_submodule(self.module, MODELS_MODULE_NAME):
            models_module_name = "%s.%s" % (self.name, MODELS_MODULE_NAME)
            self.models_module = import_module(models_module_name)

 self.clear_cache()

self.models_ready = True

# Phase 3: run ready() methods of app configs.
for app_config in self.get_app_configs():
    app_config.ready()

self.ready = True
self.ready_event.set()

        if settings.configured:
            # Start the auto-reloading dev server even if the code is broken.
            # The hardcoded condition is a code smell but we can't rely on a
            # flag on the command class because we haven't located it yet.
            if subcommand == "runserver" and "--noreload" not in self.argv:
                try:
                    autoreload.check_errors(django.setup)()
                except Exception:
                    # The exception will be raised later in the child process
                    # started by the autoreloader. Pretend it didn't happen by
                    # loading an empty list of applications.
                    apps.all_models = defaultdict(dict)
                    apps.app_configs = {}
                    apps.apps_ready = apps.models_ready = apps.ready = True

                    # Remove options not compatible with the built-in runserver
                    # (e.g. options for the contrib.staticfiles' runserver).
                    # Changes here require manually testing as described in
                    # #27522.
                    _parser = self.fetch_command("runserver").create_parser(
                        "django", "runserver"
                    )
                    _options, _args = _parser.parse_known_args(self.argv[2:])
                    for _arg in _args:
                        self.argv.remove(_arg)

    def autocomplete(self):
        """
        Output completion suggestions for BASH.

        The output of this function is passed to BASH's `COMPREPLY` variable
        and treated as completion suggestions. `COMPREPLY` expects a space
        separated string as the result.

        The `COMP_WORDS` and `COMP_CWORD` BASH environment variables are used
        to get information about the cli input. Please refer to the BASH
        man-page for more information about this variables.

        Subcommand options are saved as pairs. A pair consists of
        the long option string (e.g. '--exclude') and a boolean
        value indicating if the option requires arguments. When printing to
        stdout, an equal sign is appended to options which require arguments.

        Note: If debugging this function, it is recommended to write the debug
        output in a separate file. Otherwise the debug output will be treated
        and formatted as potential completion suggestions.
        """
        # Don't complete if user hasn't sourced bash_completion file.
        if "DJANGO_AUTO_COMPLETE" not in os.environ:
            return

        cwords = os.environ["COMP_WORDS"].split()[1:]
        cword = int(os.environ["COMP_CWORD"])

        try:
            curr = cwords[cword - 1]
        except IndexError:
            curr = ""

        subcommands = [*get_commands(), "help"]
        options = [("--help", False)]

        # subcommand
        if cword == 1:
            print(" ".join(sorted(filter(lambda x: x.startswith(curr), subcommands))))
        # subcommand options
        # special case: the 'help' subcommand has no options
        elif cwords[0] in subcommands and cwords[0] != "help":
            subcommand_cls = self.fetch_command(cwords[0])
            # special case: add the names of installed apps to options
            if cwords[0] in ("dumpdata", "sqlmigrate", "sqlsequencereset", "test"):
                try:
                    app_configs = apps.get_app_configs()
                    # Get the last part of the dotted path as the app name.
                    options.extend((app_config.label, 0) for app_config in app_configs)
                except ImportError:
                    # Fail silently if DJANGO_SETTINGS_MODULE isn't set. The
                    # user will find out once they execute the command.
                    pass
            parser = subcommand_cls.create_parser("", cwords[0])
            options.extend(
                (min(s_opt.option_strings), s_opt.nargs != 0)
                for s_opt in parser._actions
                if s_opt.option_strings
            )
            # filter out previously specified options from available options
            prev_opts = {x.split("=")[0] for x in cwords[1 : cword - 1]}
            options = (opt for opt in options if opt[0] not in prev_opts)

            # filter options by current input
            options = sorted((k, v) for k, v in options if k.startswith(curr))
            for opt_label, require_arg in options:
                # append '=' to options which require args
                if require_arg:
                    opt_label += "="
                print(opt_label)
        # Exit code of the bash completion function is never passed back to
        # the user, so it's safe to always exit with 0.
        # For more details see #25420.
        sys.exit(0)

        if subcommand == "help":
            if "--commands" in args:
                sys.stdout.write(self.main_help_text(commands_only=True) + "\n")
            elif not options.args:
                sys.stdout.write(self.main_help_text() + "\n")
            else:
                self.fetch_command(options.args[0]).print_help(
                    self.prog_name, options.args[0]
                )
        # Special-cases: We want 'django-admin --version' and
        # 'django-admin --help' to work, for backwards compatibility.
        elif subcommand == "version" or self.argv[1:] == ["--version"]:
            sys.stdout.write(django.get_version() + "\n")
        elif self.argv[1:] in (["--help"], ["-h"]):
            sys.stdout.write(self.main_help_text() + "\n")
        else:
            self.fetch_command(subcommand).run_from_argv(self.argv)