Release Notes, Usage, Code
- Please see here for release notes, news and discussion (Google Group)
- Many Examples, or full Installation and Usage Docs (or the short Overview)
- Download from GitHub or Bitbucket, or as TGZ or ZIP
- Improve django_polymorphic: Report issues, discuss, post patch, or fork (GitHub, Bitbucket, Group, Mail)
What is django_polymorphic good for?
Example: If we define the model
Project as the base class for
ResearchProject, and we store one of
each into the database, then we can do:
>>> Project.objects.all() . [ <Project: id 1, topic: "John's Gathering">, <ArtProject: id 2, topic: "Sculpting with Tim", artist: "T. Turner">, <ResearchProject: id 3, topic: "Swallow Aerodynamics", supervisor: "Dr. Winter"> ]
In general: django_polymorphic implements seamless polymorphic inheritance for Django models.
The effect: objects are always returned back from the database just as you created them, with the same type/class and fields.
It doesn't matter how these objects are retrieved: be it through the model's own managers/querysets, ForeignKeys, ManyToManyFields or OneToOneFields.
As seen in this example, the resulting querysets are polymorphic, and will typically deliver objects of several different types in a single query result.
django_polymorphic does this only for models that explicitely enable it (and for their submodels).
It's important to consider that this code is very new and to some extent still experimental. Please see the docs for current restrictions, caveats, and performance implications.
It does seem to work very well for a number of people, but API changes, code reorganisations or further schema changes are still a possibility. There may also remain larger bugs and problems in the code that have not yet been found.
django_polymorphic uses the same license as Django (BSD-like).
API Change on February 22, plus Installation Note
The django_polymorphic source code has been restructured and as a result needs to be installed like a normal Django App - either via copying the "polymorphic" directory into your Django project or by running setup.py. Adding 'polymorphic' to INSTALLED_APPS in settings.py is still optional, however.
The file polymorphic.py cannot be used as a standalone extension module anymore (as is has been split into a number of smaller files).
Importing works slightly different now: All relevant symbols are imported directly from 'polymorphic' instead from 'polymorphic.models':
# new way from polymorphic import PolymorphicModel, ... # old way, doesn't work anymore from polymorphic.models import PolymorphicModel, ...