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Django Finite State Machine Log

Build Status Code Health

Automatic logging for the excellent Django FSM package.

Logs can be accessed before a transition occurs and before they are persisted to the database by enabling a cached backend. See Advanced Usage

Compatability

  • Python 2.7 and 3.3+
  • Django 1.6+
  • South (if using 1.6) or 1.7 core migrations
  • Django-FSM 2+

Installation

First, install the package with pip. This will automatically install any dependencies you may be missing

pip install django-fsm-log

Register django_fsm_log in your list of Django applications:

INSTALLED_APPS = (
    ...,
    django_fsm_log,
    ...,
)

Then migrate the app to create the database table

python manage.py migrate django_fsm_log

Usage

The app will listen for django_fsm.signals.post_transition to be fired and create a new record for each transition.

To query logs simply

from django_fsm_log.models import StateLog
StateLog.objects.all()
# ...all recorded logs...

for_ Manager Method

For convenience there is a custom for_ manager method to easily filter on the generic foreign key

from my_app.models import Article
from django_fsm_log.models import StateLog

article = Article.objects.all()[0]

StateLog.objects.for_(article)
# ...logs for article...

by Decorator

We found that our transitions are commonly called by a user, so we've added a decorator to make logging that painless

from django.db import models
from django_fsm import FSMField, transition
from django_fsm_log.decorators import fsm_log_by

class Article(models.Model):

    state = FSMField(default='draft', protected=True)

    @fsm_log_by
    @transition(field=state, source='draft', target='submitted')
    def submit(self, by=None):
        pass

Then every time the transition is called with the by kwarg set, it will be logged

article = Article.objects.create()
article.submit(by=some_user) # StateLog.by will be some_user

Advanced Usage

You can change the behaviour of this app by turning on caching for StateLog records. Simply add DJANGO_FSM_LOG_STORAGE_METHOD = 'django_fsm_log.backends.CachedBackend' to your project's settings file. It will use your project's default cache backend by default. If you wish to use a specific cache backend, you can add to your project's settings:

DJANGO_FSM_LOG_CACHE_BACKEND = 'some_other_cache_backend'

The StateLog object is now available after the django_fsm.signals.pre_transition signal is fired, but is deleted from the cache and persisted to the database after django_fsm.signals.post_transition is fired.

This is useful if:

  • you need immediate access to StateLog details, and cannot wait until django_fsm.signals.post_transition has been fired
  • at any stage, you need to verify whether or not the StateLog has been written to the database

Access to the pending StateLog record is available via the pending_objects manager

from django_fsm_log.models import StateLog
article = Article.objects.get(...)
pending_state_log = StateLog.pending_objects.get_for_object(article)

Running Tests

$ pip install tox
$ tox