Archive of old changelog entries

2011-01-24 V1.0 Release Candidate 1

  • Fixed GitHub issue 15 (query result incomplete with inheritance). Thanks to John Debs for reporting and the test case.

2011-12-20 Renaming, refactoring, new maintainer

Since the original author disappeared from the internet, we undertook to maintain and upgrade this piece of software.

The latest “legacy” tag should be V1.0-RC-1. Anything above that should be considered experimental and unstable until further notice (there be dragons).

New features, bug fixes and other improvements will be added to trunk from now on.

2010-11-11 V1.0 Beta 2

Beta 2 accumulated somewhat more changes than intended, and also has been delayed by DBMS benchmark testing I wanted to do on model inheritance. These benchmarks show that there are considerable problems with concrete model inheritance and contemporary DBM systems. The results will be forthcoming on the google discussion forum.

Please also see:

The API should be stable now with Beta 2, so it’s just about potential bugfixes from now on regarding V1.0.

Beta 2 is still intended for testing and development environments and not for production. No complaints have been heard regarding Beta 1 however, and Beta 1 is used on a few production sites by some enterprising users.

There will be a release candidate for V1.0 in the very near future.

New Features and changes

  • API CHANGE: .extra() has been re-implemented. Now it’s polymorphic by default and works (nearly) without restrictions (please see docs). This is a (very) incompatible API change regarding previous versions of django_polymorphic. Support for the polymorphic keyword parameter has been removed. You can get back the non-polymorphic behaviour by using ModelA.objects.non_polymorphic().extra(...).

  • API CHANGE: ShowFieldContent and ShowFieldTypeAndContent now use a slightly different output format. If this causes too much trouble for your test cases, you can get the old behaviour back (mostly) by adding polymorphic_showfield_old_format = True to your model definitions. ShowField... now also produces more informative output for custom primary keys.

  • .non_polymorphic() queryset member function added. This is preferable to using .base_objects..., as it just makes the resulting queryset non-polymorphic and does not change anything else in the behaviour of the manager used (while .base_objects is just a different manager).

  • .get_real_instances(): implementation modified to allow the following more simple and intuitive use:

    >>> qs = ModelA.objects.all().non_polymorphic()
    >>> qs.get_real_instances()

    which is equivalent to:

    >>> ModelA.objects.all()
  • added member function: normal_q_object = ModelA.translate_polymorphic_Q_object(enhanced_q_object)

  • misc changes/improvements


  • Custom fields could cause problems when used as the primary key. In inherited models, Django’s automatic “.pk” field does not always work correctly for such custom fields: “” and “” return different results (which they shouldn’t, as pk should always be just an alias for the primary key field). It’s unclear yet if the problem lies in Django or the affected custom fields. Regardless, the problem resulting from this has been fixed with a small workaround. “python test polymorphic” also tests and reports on this problem now. Thanks to Mathieu Steele for reporting and the test case.

2010-10-18 V1.0 Beta 1

This release is mostly a cleanup and maintenance release that also improves a number of minor things and fixes one (non-critical) bug.

Some pending API changes and corrections have been folded into this release in order to make the upcoming V1.0 API as stable as possible.

This release is also about getting feedback from you in case you don’t approve of any of these changes or would like to get additional API fixes into V1.0.

The release contains a considerable amount of changes in some of the more critical parts of the software. It’s intended for testing and development environments and not for production environments. For these, it’s best to wait a few weeks for the proper V1.0 release, to allow some time for any potential problems to show up (if they exist).

If you encounter any such problems, please post them in the discussion group or open an issue on GitHub or BitBucket (or send me an email).

There also have been a number of minor API changes. Please see the README for more information.

New Features

  • official Django 1.3 alpha compatibility

  • PolymorphicModel.__getattribute__ hack removed. This improves performance considerably as python’s __getattribute__ generally causes a pretty large processing overhead. It’s gone now.

  • the polymorphic_dumpdata management command is not needed anymore and has been disabled, as the regular Django dumpdata command now automatically works correctly with polymorphic models (for all supported versions of Django).

  • .get_real_instances() has been elevated to an official part of the API:

    real_objects = ModelA.objects.get_real_instances(base_objects_list_or_queryset)

    allows you to turn a queryset or list of base objects into a list of the real instances. This is useful if e.g. you use ModelA.base_objects.extra(...) and then want to transform the result to its polymorphic equivalent.

  • translate_polymorphic_Q_object (see DOCS)

  • improved testing

  • Changelog added: CHANGES.rst/html


  • Removed requirement for primary key to be an IntegerField. Thanks to Mathieu Steele and Malthe Borch.

API Changes


The management command polymorphic_dumpdata is not needed anymore and has been disabled, as the regular Django dumpdata command now automatically works correctly with polymorphic models (for all supported versions of Django).

Output of Queryset or Object Printing

In order to improve compatibility with vanilla Django, printing quersets (__repr__ and __unicode__) does not use django_polymorphic’s pretty printing by default anymore. To get the old behaviour when printing querysets, you need to replace your model definition:

>>> class Project(PolymorphicModel):


>>> class Project(PolymorphicModel, ShowFieldType):

The mixin classes for pretty output have been renamed:

ShowFieldTypes, ShowFields, ShowFieldsAndTypes

are now:

ShowFieldType, ShowFieldContent and ShowFieldTypeAndContent

(the old ones still exist for compatibility)

Running the Test suite with Django 1.3

Django 1.3 requires python test polymorphic instead of just python test.


IMPORTANT: API Changed (import path changed), and 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 Adding ‘polymorphic’ to INSTALLED_APPS in is still optional, however.

The file 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, ...
  • minor API addition: ‘from polymorphic import VERSION, get_version’

New Features

Python 2.4 compatibility, contributed by Charles Leifer. Thanks!


Fix: The exception “…has no attribute ‘sub_and_superclass_dict’” could be raised. (This occurred if a subclass defined __init__ and accessed class members before calling the superclass __init__). Thanks to Mattias Brändström.

Fix: There could be name conflicts if field_name == model_name.lower() or similar. Now it is possible to give a field the same name as the class (like with normal Django models). (Found through the example provided by Mattias Brändström)


New features (and documentation)

queryset order_by method added

queryset aggregate() and extra() methods implemented

queryset annotate() method implemented

queryset values(), values_list(), distinct() documented; defer(), only() allowed (but not yet supported) added. Thanks to Andrew Ingram.

More about these additions in the docs:


  • fix remaining potential accessor name clashes (but this only works with Django 1.2+, for 1.1 no changes). Thanks to Andrew Ingram.
  • fix use of ‘id’ model field, replaced with ‘pk’.
  • fix select_related bug for objects from derived classes (till now sel.-r. was just ignored)

“Restrictions & Caveats” updated

  • Django 1.1 only - the names of polymorphic models must be unique in the whole project, even if they are in two different apps. This results from a restriction in the Django 1.1 “related_name” option (fixed in Django 1.2).
  • Django 1.1 only - when ContentType is used in models, Django’s seralisation or fixtures cannot be used. This issue seems to be resolved for Django 1.2 (changeset 11863: Fixed #7052, Added support for natural keys in serialization).


Fixed ContentType related field accessor clash (an error emitted by model validation) by adding related_name to the ContentType ForeignKey. This happened if your polymorphc model used a ContentType ForeignKey. Thanks to Andrew Ingram.


Restructured django_polymorphic into a regular Django add-on application. This is needed for the management commands, and also seems to be a generally good idea for future enhancements as well (and it makes sure the tests are always included).

The poly app - until now being used for test purposes only - has been renamed to polymorphic. See DOCS.rst (“installation/testing”) for more info.


Added the polymorphic_dumpdata management command (github issue 4), for creating fixtures, this should be used instead of the normal Django dumpdata command. Thanks to Charles Leifer.

Important: Using ContentType together with dumpdata generally needs Django 1.2 (important as any polymorphic model uses ContentType).


IMPORTANT - database schema change (more info in change log). I hope I got this change in early enough before anyone started to use in earnest. Sorry for any inconvenience. This should be the final DB schema now.

Django’s ContentType is now used instead of app-label and model-name This is a cleaner and more efficient solution Thanks to Ilya Semenov for the suggestion.