geocamUtil 0.1

geocamUtil -- Utilities used by Django apps in the GeoCam Share app collection.

geocamUtilWeb is a set of utilities used by Django web apps in the GeoCam Share app collection. It includes the following utilities.

MultiSettings

A settings container object built out of an ordered list of child settings objects. When you request the value of an attribute, it returns the value found in the first child that defines that attribute.

We typically use MultiSettings when apps extend Django settings by defining new app-specific variables. For example, if you have an app geocamAwesome you can put the following in geocamAwesome/defaultSettings.py:

GEOCAM_AWESOME_ENABLED = True

and in geocamAwesome/__init__.py:

import django.conf.settings
from geocamUtil.MultiSettings import MultiSettings
from geocamAwesome import defaultSettings

settings = MultiSettings(django.conf.settings, defaultSettings)

then you can run:

$ ./manage.py shell
>>> from geocamAwesome import settings
>>> settings.GEOCAM_AWESOME_ENABLED
True

but if a site administrator adds this line to their site-level settings.py:

GEOCAM_AWESOME_ENABLED = False

you would see:

$ ./manage.py shell
>>> from geocamAwesome import settings
>>> settings.GEOCAM_AWESOME_ENABLED
False

The advantage of this approach is that site administrators don’t need to add all of your app’s extended settings to their settings.py file if they like the defaults, but they can override any setting in a uniform way.

Actually, MultiSettings does not depend on Django at all. It will work with any kind of child container object as long as its fields can be accessed using dot notation.

models.UuidField

A Django model field that stores a universally unique identifier. When you first save a model with a UuidField, if the UUID value is not already set, it is automatically populated with a random (or “type 4”) UUID encoded as a CharField in the standard UUID display format, which is a series of hex digits separated by hyphens.

You might want to use a UuidField if you have multiple instances of your Django app on different hosts and you need to identify the same object across instances. We typically do not use a UuidField as the primary key for a model to avoid a performance penalty.

forms.UuidField

A Django form field corresponding to the same-name model field. Validates that the user entered a sequence of hex digits separated by hyphens.

models.ExtrasField

A Django model field for storing extra schema-free data. You can get and set arbitrary properties on the extra field, which can be comprised of strings, numbers, dictionaries, arrays, booleans, and None. These properties are stored in a database TextField as a JSON-encoded set of key-value pairs.