author

Chris Chambers

date

2012/05/08

Django Audited Models provides a simple abstract base class (and factory function) for tracking database record creation and modification times, as well as the creator of the record and the last user to edit it. It leverages two pluggable applications to achieve this:

1. Django Extensions, which provides (amongst many other things) a CreationDateTimeField and ModificationDateTimeField.
2. Django Threaded Multihost, originally developed for Satchmo, which provides a threadlocals mechanism that works reliably for Django installations powering multiple sites via the sites framework.

1. Install pip.
2. Run pip install django-audited-models.
3. Add threaded_multihost.middleware.ThreadLocalMiddleware to your list of MIDDLEWARE_CLASSES.
4. Inherit from AuditedModel instead of models.Model in your django applications.
5. Profit!

Django-audited-models fulfils several needs:

1. This kind of metadata is almost always useful, and inexpensive to capture -most of your clients will just presume this information is logged and will be frustrated if they can't get at it ("What do you mean we can't see who created this record?")
2. Django's admin logging functionality provides some of this detail, but is flawed in that it only captures events which take place within the admin itself.
3. This app provides a consistent, logical naming convention and interface for the metadata.
4. This app makes use of several other applications to capture this information automatically. No need to pollute your views with unrelated logic or override ModelAdmin methods to store the user who created the record.
5. It's pluggable - simply drop it in, install its requirements, inherit from AuditedModel, and you'll have your creation/modification dates and the users responsible for them, respectively. Similarly, replace your ModelAdmin with the AuditedAdmin subclass and you'll have some sensible defaults for the admin UI (readonly metadata fields, etc.).
6. As a bonus, ensures that MyModel.objects.latest() does something sensible by default - very handy when working with the interpreter, especially.

Some might question the verbosity of the time entry fields (datetime_created and datetime_modified). Consider the following:

>>> from datetime import date
>>> latest_user = User.objects.latest('date_joined')
>>> if latest_user.date_joined < date.today():
>>>     print "Nobody has joined the site today."

# Intuitively, this looks like it will work, but...
TypeError: can't compare datetime.datetime to datetime.date

Python treats datetime objects very differently to dates, and the explicit fieldnames remind the developer of this difference and help prevent errors due to incorrect assumptions.

• Python 2.5+
• Django 1.2+
• Applications listed in requirements.txt

You will also need to install the applications listed in requirements-dev.txt in order to run the test suite.