https://github.com/jazzband/django-polymorphic

Improved Django model inheritance with automatic downcasting
https://github.com/jazzband/django-polymorphic

django django-admin django-formsets django-orm

Last synced: 25 days ago
JSON representation

Improved Django model inheritance with automatic downcasting

• Host: GitHub
• URL: https://github.com/jazzband/django-polymorphic
• Owner: jazzband
• License: other
• Created: 2011-02-12T23:30:34.000Z (over 13 years ago)
• Default Branch: master
• Last Pushed: 2024-04-29T17:45:33.000Z (6 months ago)
• Last Synced: 2024-05-01T18:30:53.087Z (6 months ago)
• Topics: django, django-admin, django-formsets, django-orm
• Language: Python
• Homepage: https://django-polymorphic.readthedocs.io
• Size: 1.38 MB
• Stars: 1,574
• Watchers: 32
• Forks: 272
• Open Issues: 170
• Metadata Files:
  • Readme: README.rst
  • Contributing: CONTRIBUTING.rst
  • License: LICENSE
  • Authors: AUTHORS.rst

Awesome Lists containing this project

• best-of-web-python - GitHub - 45% open · ⏱️ 04.06.2024): (Django Utilities)

README

        
.. list-table::

    :header-rows: 0

    :widths: auto

    * - .. image:: https://github.com/jazzband/django-polymorphic/actions/workflows/test.yml/badge.svg

          :target: https://github.com/jazzband/django-polymorphic/actions/workflows/test.yml

      - .. image:: https://img.shields.io/pypi/v/django-polymorphic.svg

          :target: https://pypi.python.org/pypi/django-polymorphic/

      - .. image:: https://img.shields.io/codecov/c/github/jazzband/django-polymorphic/master.svg

          :target: https://codecov.io/github/jazzband/django-polymorphic?branch=master

      - .. image:: https://readthedocs.org/projects/django-polymorphic/badge/?version=stable

          :target: https://django-polymorphic.readthedocs.io/en/stable/

      - .. image:: https://jazzband.co/static/img/badge.svg

          :target: https://jazzband.co/

          :alt: Jazzband

Polymorphic Models for Django

=============================

Django-polymorphic simplifies using inherited models in Django projects.

When a query is made at the base model, the inherited model classes are returned.

When we store models that inherit from a ``Project`` model...

.. code-block:: python

    >>> Project.objects.create(topic="Department Party")

    >>> ArtProject.objects.create(topic="Painting with Tim", artist="T. Turner")

    >>> ResearchProject.objects.create(topic="Swallow Aerodynamics", supervisor="Dr. Winter")

...and want to retrieve all our projects, the subclassed models are returned!

.. code-block:: python

    >>> Project.objects.all()

    [ ,

      ,

       ]

Using vanilla Django, we get the base class objects, which is rarely what we wanted:

.. code-block:: python

    >>> Project.objects.all()

    [ ,

      ,

       ]

This also works when the polymorphic model is accessed via

ForeignKeys, ManyToManyFields or OneToOneFields.

Features

--------

* Full admin integration.

* ORM integration:

  * support for ForeignKey, ManyToManyField, OneToOneField descriptors.

  * Filtering/ordering of inherited models (``ArtProject___artist``).

  * Filtering model types: ``instance_of(...)`` and ``not_instance_of(...)``

  * Combining querysets of different models (``qs3 = qs1 | qs2``)

  * Support for custom user-defined managers.

* Uses the minimum amount of queries needed to fetch the inherited models.

* Disabling polymorphic behavior when needed.

**Note:** While *django-polymorphic* makes subclassed models easy to use in Django,

we still encourage to use them with caution. Each subclassed model will require

Django to perform an ``INNER JOIN`` to fetch the model fields from the database.

While taking this in mind, there are valid reasons for using subclassed models.

That's what this library is designed for!

The current release of *django-polymorphic* supports Django 2.2 - 4.0 on Python 3.6+.

For more information, see the `documentation at Read the Docs `_.

Installation

------------

Install using ``pip``\ ...

.. code:: bash

    $ pip install django-polymorphic

At the moment we have an unoffical version (4.0.0a). While we wait to gain access to pip. If you want to use the latest version (which works for Django >4.0.0). You can install it using

.. code:: bash

    pip install git+https://github.com/jazzband/[email protected]#egg=django-polymorphic

License

=======

Django-polymorphic uses the same license as Django (BSD-like).