""" 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 from pathlib import Path from django.conf import global_settings from django.core.exceptions import ImproperlyConfigured from django.utils.functional import LazyObject, empty ENVIRONMENT_VARIABLE = "DJANGO_SETTINGS_MODULE" 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 '' return '' % { 'settings_module': self._wrapped.SETTINGS_MODULE, } def __getattr__(self, name): """Return the value of a setting and cache it in self.__dict__.""" if self._wrapped is empty: self._setup(name) val = getattr(self._wrapped, name) 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 @property def configured(self): """Return True if the settings have already been configured.""" return self._wrapped is not empty 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 = ( "INSTALLED_APPS", "TEMPLATE_DIRS", "LOCALE_PATHS", ) 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 not self.SECRET_KEY: raise ImproperlyConfigured("The SECRET_KEY setting must not be empty.") 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) 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()