DRY way to add created/modified by and time

The create/modification dates can be handled by Django now, so they can be implemented like:

class BaseModel(models.Model):
    created_date = models.DateTimeField(auto_now_add=True)
    modified_date = models.DateTimeField(auto_now=True)

    class Meta:
        abstract = True

By adding this to a abstract model base class, it can be easily added to all models of the application.

Storing the user is harder, since the request.user is not available. As SeanOC mentioned, this is a separation of concerns between the web request, and model layer. Either you pass this field all the time, or store request.user in a threadlocal. Django CMS does this for their permission system.

class CurrentUserMiddleware(object):
    def process_request(self, request):
        set_current_user(getattr(request, 'user', None))

And the user tracking happens elsewhere:

from threading import local
_thread_locals = local()

def set_current_user(user):
    _thread_locals.user=user

def get_current_user():
    return getattr(_thread_locals, 'user', None)

For non-web environments (e.g. management commands), you’d have to call set_current_user at the start of the script.