This is a pre-production deployment of Warehouse, however changes made here WILL affect the production instance of PyPI.
Latest Version Dependencies status unknown Test status unknown Test coverage unknown
Project Description
=================
Django Principals
=================

This module provides ``PrincipalField``, a model field for Django_ that allows
instances of a model to be defined as the principal instance for an entire model or
a collection of instances. When the status of one instance is changed, the status
of other items in the collection are updated in response as necessary.


Usage
-----

Add a ``PrincipalField`` to your model; that's it.

If you want to work with all instances of the model as a single collection,
there's nothing else required. To create collections based on one or more
fields on the model, specify the field names using the ``collection`` argument.

In general, the value assigned to a ``PrincipalField`` will be handled like a
unique Boolean value. Setting the principal to ``True`` will
cause all other items to become ``False``within the same collection --
unless, of course, the collection has fewer than two elements.

Multi-table model inheritance
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

By default, if a parent model has a principal field that declares a collection,
child model instances are filtered independently. This behavior can be changed
by specifying a `parent_link` argument identifying the name of the one-to-one
field linking the child model to the parent. If `parent_link` is set, all subclass
instances will be part of a single sequence in each collection.


Limitations
-----------

* Unique constraints can't be applied to ``PrincipalField`` because they break
the ability to update other items in a collection all at once. This one was
a bit painful, because setting the constraint is probably the right thing to
do from a database consistency perspective, but the overhead in additional
queries was too much to bear.

Credits
-------

This code loosely draws on concepts inspired by django-positions_ and django-featured-item_,
two projects which provide custom model fields with different functionality.


.. _`Django`: http://www.djangoproject.com/

.. _`django-positions`: https://github.com/jpwatts/django-positions

.. _`django-featured-item`: https://bitbucket.org/tim_heap/django-featured-item
Release History

Release History

0.1.5

This version

History Node

TODO: Figure out how to actually get changelog content.

Changelog content for this version goes here.

Donec et mollis dolor. Praesent et diam eget libero egestas mattis sit amet vitae augue. Nam tincidunt congue enim, ut porta lorem lacinia consectetur. Donec ut libero sed arcu vehicula ultricies a non tortor. Lorem ipsum dolor sit amet, consectetur adipiscing elit.

Show More

0.1.4

History Node

TODO: Figure out how to actually get changelog content.

Changelog content for this version goes here.

Donec et mollis dolor. Praesent et diam eget libero egestas mattis sit amet vitae augue. Nam tincidunt congue enim, ut porta lorem lacinia consectetur. Donec ut libero sed arcu vehicula ultricies a non tortor. Lorem ipsum dolor sit amet, consectetur adipiscing elit.

Show More

Download Files

Download Files

TODO: Brief introduction on what you do with files - including link to relevant help section.

File Name & Checksum SHA256 Checksum Help Version File Type Upload Date
django-principals-0.1.5.tar.gz (5.4 kB) Copy SHA256 Checksum SHA256 Source Oct 29, 2013

Supported By

WebFaction WebFaction Technical Writing Elastic Elastic Search Pingdom Pingdom Monitoring Dyn Dyn DNS HPE HPE Development Sentry Sentry Error Logging CloudAMQP CloudAMQP RabbitMQ Heroku Heroku PaaS Kabu Creative Kabu Creative UX & Design Fastly Fastly CDN DigiCert DigiCert EV Certificate Rackspace Rackspace Cloud Servers DreamHost DreamHost Log Hosting