django-delta-logger 0.1.1

Model instance change logging for django models.

Django Delta Logger

A django app that provides a model class that records changes in django models.

Installation

Get the Package

pip install django_delta_logger

Update the Django Settings

Add django_delta_logger to the INSTALLED_APPS list.

INSTALLED_APPS=[
    # ...
    'django_delta_logger',
    # ...
]

Make sure JSON_ENCODER is set in the django settings. A reasonable default is provided and is directly importable into an existing settings file.

from django_delta_logger.settings import JSON_ENCODER

Usage

Django_delta_logger's primary API is a context manager:

from django_delta_logger.delta_logger import DeltaLogger

with DeltaLogger(SomeDjangoModel, SomeOtherDjangoModel):
    foo = SomeDjangoModel(name='foo')
    foo.save()

Log Results

Access the history of a model instance from the DeltaEvent model.

from django_delta_logger.models import DeltaEvent

instance = SomeModel.objects.get(pk=1)
events = DeltaEvent.objects.get_for_instance(instance).all()

for event in events:
    print(event.event_time, event.event_type, event.event_data)

from django_delta_logger.models import DeltaEvent

events = DeltaEvent.objects.get_for_model(SomeDjangoModel).all()

for event in events:
    print(event.event_time, event.event_type, event.event_data)

The Risks of Concurrency

Tracking the dirtyness of a model instance field is performant but can lead to inaccurate log data when one model instance is edited in multiple threads/processes/servers.

When data accuracy in a concurrent environment is worth the performance cost of a fetch-before-write:

from django_delta_logger.delta_logger import DeltaLogger

with DeltaLogger(SomeDjangoModel, concurrent=True):
    foo = SomeDjangoModel(name='foo')
    foo.save()

Test Suite

python setup.py test

License

This software is published under the MIT License. See the LICENSE file for details.