django/conf/__init__.py
"""
Settings and configuration for Django.
Read values from the module specified by the DJANGO_SETTINGS_MODULE environment
variable, and then from django.conf.global_settings; see the global_settings.py
for a list of all possible variables.
"""
import importlib
import os
import time
import traceback
import warnings
from pathlib import Path
import django
from django.conf import global_settings
from django.core.exceptions import ImproperlyConfigured
from django.utils.deprecation import RemovedInDjango60Warning
from django.utils.functional import LazyObject, empty
ENVIRONMENT_VARIABLE = "DJANGO_SETTINGS_MODULE"
DEFAULT_STORAGE_ALIAS = "default"
STATICFILES_STORAGE_ALIAS = "staticfiles"
# RemovedInDjango60Warning.
FORMS_URLFIELD_ASSUME_HTTPS_DEPRECATED_MSG = (
"The FORMS_URLFIELD_ASSUME_HTTPS transitional setting is deprecated."
)
class SettingsReference(str):
"""
String subclass which references a current settings value. It's treated as
the value in memory but serializes to a settings.NAME attribute reference.
"""
def __new__(self, value, setting_name):
return str.__new__(self, value)
def __init__(self, value, setting_name):
self.setting_name = setting_name
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)
# 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)
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)
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.")
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
def _show_deprecation_warning(self, message, category):
stack = traceback.extract_stack()
# Show a warning if the setting is used outside of Django.
# Stack index: -1 this line, -2 the property, -3 the
# LazyObject __getattribute__(), -4 the caller.
filename, _, _, _ = stack[-4]
if not filename.startswith(os.path.dirname(django.__file__)):
warnings.warn(message, category, stacklevel=2)
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)
if self.is_overridden("FORMS_URLFIELD_ASSUME_HTTPS"):
warnings.warn(
FORMS_URLFIELD_ASSUME_HTTPS_DEPRECATED_MSG,
RemovedInDjango60Warning,
)
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()
def is_overridden(self, setting):
return setting in self._explicit_settings
def __repr__(self):
return '<%(cls)s "%(settings_module)s">' % {
"cls": self.__class__.__name__,
"settings_module": self.SETTINGS_MODULE,
}
class UserSettingsHolder:
"""Holder for user configured settings."""
# SETTINGS_MODULE doesn't make much sense in the manually configured
# (standalone) case.
SETTINGS_MODULE = None
def __init__(self, default_settings):
"""
Requests for configuration variables not in this class are satisfied
from the module specified in default_settings (if possible).
"""
self.__dict__["_deleted"] = set()
self.default_settings = default_settings
def __getattr__(self, name):
if not name.isupper() or name in self._deleted:
raise AttributeError
return getattr(self.default_settings, name)
def __setattr__(self, name, value):
self._deleted.discard(name)
if name == "FORMS_URLFIELD_ASSUME_HTTPS":
warnings.warn(
FORMS_URLFIELD_ASSUME_HTTPS_DEPRECATED_MSG,
RemovedInDjango60Warning,
)
super().__setattr__(name, value)
def __delattr__(self, name):
self._deleted.add(name)
if hasattr(self, name):
super().__delattr__(name)
def __dir__(self):
return sorted(
s
for s in [*self.__dict__, *dir(self.default_settings)]
if s not in self._deleted
)
def is_overridden(self, setting):
deleted = setting in self._deleted
set_locally = setting in self.__dict__
set_on_default = getattr(
self.default_settings, "is_overridden", lambda s: False
)(setting)
return deleted or set_locally or set_on_default
def __repr__(self):
return "<%(cls)s>" % {
"cls": self.__class__.__name__,
}
settings = LazySettings()