A Django settings file contains all the configuration of your Django installation. This document explains how settings work and which settings are available.
A settings file is just a Python module with module-level variables.
Here are a couple of example settings:
ALLOWED_HOSTS = ['www.example.com']
DEBUG = False
DEFAULT_FROM_EMAIL = '[email protected]'
Note
If you set DEBUG to False, you also need to properly set
the ALLOWED_HOSTS setting.
Because a settings file is a Python module, the following apply:
It doesn’t allow for Python syntax errors.
It can assign settings dynamically using normal Python syntax. For example:
MY_SETTING = [str(i) for i in range(30)]
It can import values from other settings files.
DJANGO_SETTINGS_MODULE¶When you use Django, you have to tell it which settings you’re using. Do this
by using an environment variable, DJANGO_SETTINGS_MODULE.
The value of DJANGO_SETTINGS_MODULE should be in Python path syntax, e.g.
mysite.settings. Note that the settings module should be on the
Python import search path.
django-admin utility¶When using django-admin, you can either set the environment variable once, or explicitly pass in the settings module each time you run the utility.
Example (Unix Bash shell):
export DJANGO_SETTINGS_MODULE=mysite.settings
django-admin runserver
Example (Windows shell):
set DJANGO_SETTINGS_MODULE=mysite.settings
django-admin runserver
Use the --settings command-line argument to specify the settings manually:
django-admin runserver --settings=mysite.settings
mod_wsgi)¶In your live server environment, you’ll need to tell your WSGI
application what settings file to use. Do that with os.environ:
import os
os.environ['DJANGO_SETTINGS_MODULE'] = 'mysite.settings'
Read the Django mod_wsgi documentation for more information and other common elements to a Django WSGI application.
A Django settings file doesn’t have to define any settings if it doesn’t need
to. Each setting has a sensible default value. These defaults live in the
module django/conf/global_settings.py.
Here’s the algorithm Django uses in compiling settings:
global_settings.py.Note that a settings file should not import from global_settings, because
that’s redundant.
There’s an easy way to view which of your settings deviate from the default
settings. The command python manage.py diffsettings displays differences
between the current settings file and Django’s default settings.
For more, see the diffsettings documentation.
In your Django apps, use settings by importing the object
django.conf.settings. Example:
from django.conf import settings
if settings.DEBUG:
# Do something
Note that django.conf.settings isn’t a module – it’s an object. So
importing individual settings is not possible:
from django.conf.settings import DEBUG # This won't work.
Also note that your code should not import from either global_settings or
your own settings file. django.conf.settings abstracts the concepts of
default settings and site-specific settings; it presents a single interface.
It also decouples the code that uses settings from the location of your
settings.
You shouldn’t alter settings in your applications at runtime. For example, don’t do this in a view:
from django.conf import settings
settings.DEBUG = True # Don't do this!
The only place you should assign to settings is in a settings file.
Because a settings file contains sensitive information, such as the database password, you should make every attempt to limit access to it. For example, change its file permissions so that only you and your Web server’s user can read it. This is especially important in a shared-hosting environment.
For a full list of available settings, see the settings reference.
There’s nothing stopping you from creating your own settings, for your own Django apps. Just follow these guidelines:
For settings that are sequences, Django itself uses lists, but this is only a convention.
DJANGO_SETTINGS_MODULE¶In some cases, you might want to bypass the DJANGO_SETTINGS_MODULE
environment variable. For example, if you’re using the template system by
itself, you likely don’t want to have to set up an environment variable
pointing to a settings module.
In these cases, you can configure Django’s settings manually. Do this by calling:
django.conf.settings.configure(default_settings, **settings)¶Example:
from django.conf import settings
settings.configure(DEBUG=True)
Pass configure() as many keyword arguments as you’d like, with each keyword
argument representing a setting and its value. Each argument name should be all
uppercase, with the same name as the settings described above. If a particular
setting is not passed to configure() and is needed at some later point,
Django will use the default setting value.
Configuring Django in this fashion is mostly necessary – and, indeed, recommended – when you’re using a piece of the framework inside a larger application.
Consequently, when configured via settings.configure(), Django will not
make any modifications to the process environment variables (see the
documentation of TIME_ZONE for why this would normally occur). It’s
assumed that you’re already in full control of your environment in these
cases.
If you’d like default values to come from somewhere other than
django.conf.global_settings, you can pass in a module or class that
provides the default settings as the default_settings argument (or as the
first positional argument) in the call to configure().
In this example, default settings are taken from myapp_defaults, and the
DEBUG setting is set to True, regardless of its value in
myapp_defaults:
from django.conf import settings
from myapp import myapp_defaults
settings.configure(default_settings=myapp_defaults, DEBUG=True)
The following example, which uses myapp_defaults as a positional argument,
is equivalent:
settings.configure(myapp_defaults, DEBUG=True)
Normally, you will not need to override the defaults in this fashion. The
Django defaults are sufficiently tame that you can safely use them. Be aware
that if you do pass in a new default module, it entirely replaces the Django
defaults, so you must specify a value for every possible setting that might be
used in that code you are importing. Check in
django.conf.settings.global_settings for the full list.
configure() or DJANGO_SETTINGS_MODULE is required¶If you’re not setting the DJANGO_SETTINGS_MODULE environment variable, you
must call configure() at some point before using any code that reads
settings.
If you don’t set DJANGO_SETTINGS_MODULE and don’t call configure(),
Django will raise an ImportError exception the first time a setting
is accessed.
If you set DJANGO_SETTINGS_MODULE, access settings values somehow, then
call configure(), Django will raise a RuntimeError indicating
that settings have already been configured. There is a property just for this
purpose:
For example:
from django.conf import settings
if not settings.configured:
settings.configure(myapp_defaults, DEBUG=True)
Also, it’s an error to call configure() more than once, or to call
configure() after any setting has been accessed.
It boils down to this: Use exactly one of either configure() or
DJANGO_SETTINGS_MODULE. Not both, and not neither.
django.setup() is required for “standalone” Django usage¶If you’re using components of Django “standalone” – for example, writing a Python script which loads some Django templates and renders them, or uses the ORM to fetch some data – there’s one more step you’ll need in addition to configuring settings.
After you’ve either set DJANGO_SETTINGS_MODULE or called
configure(), you’ll need to call django.setup() to load your
settings and populate Django’s application registry. For example:
import django
from django.conf import settings
from myapp import myapp_defaults
settings.configure(default_settings=myapp_defaults, DEBUG=True)
django.setup()
# Now this script or any imported module can use any part of Django it needs.
from myapp import models
Note that calling django.setup() is only necessary if your code is truly
standalone. When invoked by your Web server, or through django-admin, Django will handle this for you.
django.setup() may only be called once.
Therefore, avoid putting reusable application logic in standalone scripts
so that you have to import from the script elsewhere in your application.
If you can’t avoid that, put the call to django.setup() inside an
if block:
if __name__ == '__main__':
import django
django.setup()
See also
Oct 31, 2018