django-json-settings2 0.1

Saving Settings

You’re going to need to save your desired settings to a json file first. There’s a simple helper function, and management command, included to help.

For instance, say you want to create a simple setting for your SECRET_KEY variable:

$ python
>>> settings_to_save = ['SECRET_KEY']
>>> from json_settings2 import write_settings_from_django
>>> write_settings_from_django(*settings_to_save)
>>> exit()
$ cat .settings.json
{
    "SECRET_KEY": "SUPER SECRET KEY IS HERE! COOOOOOOLLLLL!"
}
$

The write_settings_from_django function takes a few optional variables:

• settings_vars = Positional args giving every Django setting to save

• filename = Filename of the json settings file. Defaults to .settings.json

• directory = Directory in which to save filename. Defaults to ..

• indent = Indentation level for the json output. Set to None for the most

  compact file. Defaults to 4.

• force = If directory/filename exists, overwrite it.

  Defaults to False

You can also just use the management command. This requires that you place json_settings2 in your INSTALLED_APPS setting:

$ python manage.py write_json_settings SECRET_KEY

You can add as many settings as you’d like too:

$ python manage.py write_json_settings SECRET_KEY DATABASES STATIC_URL

To see the options, simply:

$ python manage.py help write_json_settings

Loading Settings

The easiest way is to store all your default and local settings in settings.py and load the json settings at the end. It’s pretty straight forward. Let’s see an example:

$ cat settings.py
import os
from json_settings2 import load_settings

DEBUG = True
STATIC_URL = '/static/'
... LOTS OF OTHERS SETTINGS HERE ...

SETTINGS_DIR = os.path.dirname(os.path.abspath(__file__))
load_settings(globals(), directory=SETTINGS_DIR, depth=3)

Essentially this will tell the function to look for the settings file starting in the same directory as settings.py and if not found, look up to 3 levels higher in the directory tree. So let’s say the path if your settings.py file is /home/user/app/current/code/settings.py

The load_settings function will search the following paths for .settings.json:

• /home/user/app/current/code/

• /home/user/app/current/

• /home/user/app/

• /home/user/

Useful if you want to store your settings outside of the code deployment directories, which is often the case.

The load_settings function takes the following variables:

• current_settings - Dictionary that will be updated with found settings.

  Generally you’d pass in globals().

• filename - Name of json file with settings. Defaults to .settings.json

• directory - Path of the directory where filename lives. Defaults to ..

• depth - Number of parent directories to scan for filename. Defaults to 0.

• store = Store settings into the current_settings dict. Defaults to True.

If store is set to False then the current_settings dict will not be altered.

The function will always return the pythonic representation of what was found in the json settings file.

Note on directory - By default, the directory variable above is set to . - meaning current directory. This usually means the directory where you started the Python interpreter or are running manage.py from. This is usually NOT what you want. It’s best practice to always set the expected directory to avoid troubleshooting headaches.

What Is Used As a Setting?

When calling load_settings you can include extra data in your json settings file that is useful for other puposes in your code but is not something you want cluttering your django.conf.settings object.

Only keys that are stored in all capital letters will be stored to the current_settings dict. So if your json settings has options that are not all caps, they will only be returned as part of the loaded json data.

In other words, say you load_settings on the following data:

{
    "SeCreT_Key": "This will not be saved in Django settings.",
    "SECRET_KEY": "This WILL be saved in Django settings.",
    "secret_key": :This will not be saved in Django settings."
}

Your SECRET_KEY setting will be set to This WILL be saved in Django settings.

Where To Load Settings?

Normally you can place it at the bottom of the settings.py file. However, there are often times that you need those settings to guide the values of other settings.

There is nothing stopping you from loading your json settings from anywhere in the process. It’s up to you. Just remember that if you load your settings and then set a duplicate variable AFTER loading the json settings, the duplicate variable will have the final say.

For example:

$ cat .setting.json
{
    "STATIC_URL": "/my/cool/static/url/"
}
$ cat settings.py
import os
from json_settings2 import load_settings

SETTINGS_DIR = os.path.dirname(os.path.abspath(__file__))
load_settings(globals(), directory=SETTINGS_DIR, depth=3)

DEBUG = True
STATIC_URL = '/static/'
... LOTS OF OTHERS SETTINGS HERE ...

The value of your STATIC_URL setting will be set to /static/ when you might be expecting it to be /my/cool/static/url/. Just a heads up.