Take a look at https://github.com/zapier/django-stalefields for a newer, better supported version!

Tracking changed fields on a Django model instance.

Makes a Mixin available that will give you the properties:

• is_dirty
• dirty_fields

As well as the methods:

• save_dirty()

Which will will selectively only update dirty columns using the familiar Model.objects.filter(pk=pk).update(**dirty_fields) pattern (but still resolves F() or auto_now constructs).

It's always annoying to browse various active branches with no context about how they differ outside of diffs. So, we'll just tell you! :-)

We're building off the dirtyfields branch by Calloway Project that added some update() features around dirty fields. However, we fixed two bugs:

• Pre/Post save events have proper kwargs passed in.
• foreign_key_id attributes that accompany foreign_key model fields are properly handled.

Thats it really! We've also added a few tests around save_dirty(). Enjoy!

Install the package using pip. Then use the instructions in "Using the Mixin in the Model".

$ pip install django-dirtyfields

or if you're interested in developing it, use virtualenv and virtualenvwrapper. The default settings.py will look for the dirtyfields package in its current location.

$ mkvirtualenv django-dirtyfields
(django-dirtyfields)$ pip install -r example_app/requirements.pip
(django-dirtyfields)$ example_app/manage.py test testing_app

from django.db import models
from dirtyfields import DirtyFieldsMixin

class TestModel(DirtyFieldsMixin, models.Model):
    """A simple test model to test dirty fields mixin with"""
    boolean = models.BooleanField(default=True)
    characters = models.CharField(blank=True, max_length=80)

(ve)$ ./manage.py shell
>>> from testing_app.models import TestModel
>>> tm = TestModel(boolean=True, characters="testing")
>>> tm.save()
>>> tm.is_dirty
False
>>> tm.dirty_fields
()
>>> tm.boolean = False
>>> tm.is_dirty
True
>>> tm.dirty_fields
('boolean', )
>>> tm.characters = "have changed"
>>> tm.is_dirty
True
>>> tm.dirty_fields
('boolean', 'characters', )
>>> tm.save()
>>> tm.is_dirty
False
>>> tm.get_dirty_fields
()

When using signals, especially pre_save, it is useful to be able to see what fields have changed or not. A signal could change its behaviour depending on whether a specific field has changed, whereas otherwise, you only could work on the event that the model's save() method had been called.

This code has largely be adapted from what was made available at Stack Overflow.