how to change the implicit default settings in django 1.6

Question

the 'implicit' I mean is that in Django 1.6 some settings are omitted in the generated settings.py (by django-admin startproject), for example, in the settings.py there won't be TEMPLATE_LOADERS placed there, but it actually has a default value:

$ ./manage.py shell
>>> from django.conf import settings
>>> print settings.TEMPLATE_LOADERS
    ('django.template.loaders.filesystem.Loader',
     'django.template.loaders.app_directories.Loader')

I've tried with updating the settings.py like this:

TEMPLATE_LOADERS += (
    'django.template.loaders.eggs.Loader',
)

but it will fail with the following error:

NameError: name 'TEMPLATE_LOADERS' is not defined

I'm just wondering whether there is a best practice to add additional template loaders to the default list without doing it like this (which a little ugly to repeat the default loaders):

TEMPLATE_LOADERS = (
    'django.template.loaders.filesystem.Loader',
    'django.template.loaders.app_directories.Loader',
    'django.template.loaders.eggs.Loader',
)

Answer 1

You are trying to update a non defined variable, you should create or import it. The default setting values are defined in django.conf.global_settings. If you add this line to the top of the file it should work:

from django.conf.global_settings import TEMPLATE_LOADERS

Not sure if it is a good practice either because you may want to know exactly which settings are you using.

The complete list of default settings is here:

django.conf.global_settings

And this is the mechanism Django uses to override default settings with user settings where mod are the user settings and global_settings are the default settings:

# django/conf/__init__.py

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

    try:
        mod = importlib.import_module(self.SETTINGS_MODULE)
    except ImportError as e:
        raise ImportError(
            "Could not import settings '%s' (Is it on sys.path? Is there an import error in the settings file?): %s"
            % (self.SETTINGS_MODULE, e)
        )

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

            if (setting in tuple_settings and
                    isinstance(setting_value, six.string_types)):
                raise ImproperlyConfigured("The %s setting must be a tuple. "
                        "Please fix your settings." % setting)
            setattr(self, setting, setting_value)
            self._explicit_settings.add(setting)