django-papertrail

An elegant solution for keeping a relational log of chronological events in a Django application.

Installation

To install django-papertrail:

$ pip install django-papertrail

To enable django-papertrail in your project you need to add it to INSTALLED_APPS in your projects settings.py file:

INSTALLED_APPS = (
    ...
    'papertrail',
    ...
)

After that, you should migrate:

$ python manage.py migrate

Using it

import papertrail

###########################################################################
# Creating entries
###########################################################################

# Basic usage. Timestamp defaults to now
papertrail.log('cache-flushed', 'Cache was flushed!')

# Optional data
papertrail.log(
    'periodic-cleanup-ran',
    'Periodic cleanup task executed.',
    data={
        'success': True,
        'cleaned_objects': 100,
    }
)

# Optional targets
papertrail.log(
    'user-logged-in',
    u'{} logged in'.format(request.user.get_full_name()),
    targets={
        'user': request.user,
    }
)

# Optional timestamp
papertrail.log(
    'user-joined',
    'User joined site',
    targets={
        'user': request.user,
    },
    timestamp=request.user.date_joined,
)

# Multiple targets
user1 = User.objects.get(...)
user2 = User.objects.get(...)
papertrail.log(
    'user-followed',
    'User followed another user',
    targets={
        'follower': user1,
        'following': user2,
    },
)

###########################################################################
# Querying the papertrail
###########################################################################

# Gettying all papertrail entries that points to user1, without taking
# into account the target relationship name
qs = papertrail.related_to(user)
entry = qs.first()
print '[{}] {} ({}) - {}'.format(
    entry.timestamp, entry.type, entry.message, entry.data
)

# Get all entry that points to both users
# (Will only return entries that have both user1 and user2 in their
#  targets)
qs = papertrail.related_to(user1, user2)

# Query specific relationships, such as user1 following user2
qs = papertrail.related_to(follower=user1, following=user2)

# Filtering entry by a specific type (or any Django ORM filter)
qs = papertrail.filter(type='user-followed')

# And chaining
qs = papertrail.filter(type='user-followed').related_to(follower=user1)

# Get all the users that have followed a specific user (user1). This might
# look a bit confusing at first, but can be very useful.
# The objects_represented filter allows filtering a given queryset to contain
# only elements that have a specific papertrail entry pointing at them.
all_users = get_user_model().objects.all()
users_who_followed_user1 = (papertrail
    # Narrow down to only user-followed entries that followed user1
    .filter(type='user-followed')
    .related_to(following=user1)
    # Return a User queryset that only has the users for which we have a
    # user-followed entry that has a followed target pointing at them
    .objects_represented(all_users, 'followed')
)

# objects_not_represented does the same, but returns a queryset that
# excludes any object that has a papertrail entry pointing at it:
# Get all users who never logged in
users_who_never_logged_in = (papertrail
    .filter(type='user-logged-in')
    .objects_not_represented(all_users, 'user')
)

Admin integration

django-papertrail provides a Django admin integration to both view entries (simple Django admin Entry list, usually available under /admin/papertrail/entry/) as well as a more advanced intergration for objects you want to keep track of.

The advanced integration provides two useful functionalities:

Change tracking - whenever an object for which the integration is enabled is added/edited/deleted, a papertrail entry will be created
A convenient link to view all papertrail entries pointing to the object being viewed as well as an integrated papertrail viewer:

To enable the integration, your ModelAdmin class needs to inherit from AdminEventLoggerMixin:

from papertrail.admin import AdminEventLoggerMixin

class MyObjectAdmin(AdminEventLoggerMixin, admin.ModelAdmin):
    pass

    # The admin papertrail viewer can have filters:
    papertrail_type_filters = {
        'Login events': (
            'user-logged-in',
            'user-logged-out',
        ),
        'Social events': (
            'user-followed',
            'user-unfollowed',
        ),
    }