108 lines
3.7 KiB
Python
108 lines
3.7 KiB
Python
from inspect import getmembers
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from django.conf import settings
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class AppSettings(object):
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"""
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An app setting object to be used for handling app setting defaults
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gracefully and providing a nice API for them. Say you have an app
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called ``myapp`` and want to define a few defaults, and refer to the
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defaults easily in the apps code. Add a ``settings.py`` to your app::
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from path.to.utils import AppSettings
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class MyAppSettings(AppSettings):
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SETTING_1 = "one"
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SETTING_2 = (
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"two",
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)
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Then initialize the setting with the correct prefix in the location of
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of your choice, e.g. ``conf.py`` of the app module::
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settings = MyAppSettings(prefix="MYAPP")
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The ``MyAppSettings`` instance will automatically look at Django's
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global setting to determine each of the settings and respect the
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provided ``prefix``. E.g. adding this to your site's ``settings.py``
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will set the ``SETTING_1`` setting accordingly::
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MYAPP_SETTING_1 = "uno"
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Usage
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-----
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Instead of using ``from django.conf import settings`` as you would
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usually do, you can switch to using your apps own settings module
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to access the app settings::
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from myapp.conf import settings
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print myapp_settings.MYAPP_SETTING_1
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``AppSettings`` instances also work as pass-throughs for other
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global settings that aren't related to the app. For example the
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following code is perfectly valid::
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from myapp.conf import settings
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if "myapp" in settings.INSTALLED_APPS:
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print "yay, myapp is installed!"
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Custom handling
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---------------
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Each of the settings can be individually configured with callbacks.
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For example, in case a value of a setting depends on other settings
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or other dependencies. The following example sets one setting to a
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different value depending on a global setting::
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from django.conf import settings
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class MyCustomAppSettings(AppSettings):
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ENABLED = True
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def configure_enabled(self, value):
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return value and not self.DEBUG
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custom_settings = MyCustomAppSettings("MYAPP")
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The value of ``custom_settings.MYAPP_ENABLED`` will vary depending on the
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value of the global ``DEBUG`` setting.
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Each of the app settings can be customized by providing
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a method ``configure_<lower_setting_name>`` that takes the default
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value as defined in the class attributes as the only parameter.
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The method needs to return the value to be use for the setting in
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question.
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"""
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def __dir__(self):
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return sorted(list(set(self.__dict__.keys() + dir(settings))))
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__members__ = lambda self: self.__dir__()
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def __getattr__(self, name):
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if name.startswith(self._prefix):
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raise AttributeError("%r object has no attribute %r" %
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(self.__class__.__name__, name))
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return getattr(settings, name)
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def __setattr__(self, name, value):
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super(AppSettings, self).__setattr__(name, value)
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if name in dir(settings):
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setattr(settings, name, value)
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def __init__(self, prefix):
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super(AppSettings, self).__setattr__('_prefix', prefix)
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for name, value in filter(self.issetting, getmembers(self.__class__)):
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prefixed_name = "%s_%s" % (prefix.upper(), name.upper())
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value = getattr(settings, prefixed_name, value)
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callback = getattr(self, "configure_%s" % name.lower(), None)
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if callable(callback):
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value = callback(value)
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delattr(self.__class__, name)
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setattr(self, prefixed_name, value)
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def issetting(self, (name, value)):
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return name == name.upper()
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