Django Finite State Machine Log

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

Changelog

1.7.0 (unreleased)

1.6.2 (2019-01-06)

• Address Migration history breakage added in 1.6.1

1.6.1 (2018-12-02)

• Make StateLog.description field nullable

1.6.0 (2018-11-14)

• Add source state on transitions
• Fixed get_state_display with FSMIntegerField (#63)
• Fixed handling of transitions if target is None (#71)
• Added fsm_log_description decorator (#1, #67)
• Dropped support for Django 1.10 (#64)

1.5.0 (2017-11-29)

• cleanup deprecated code.
• add codecov support.
• switch to pytest.
• add Admin integration to visualize past transitions.

1.4.0 (2017-11-09)

• Bring compatibility with Django 2.0 and drop support of unsupported versions of Django: 1.6, 1.7, 1.9.

Compatibility

• Python 2.7 and 3.4+
• Django 1.8+
• 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 listens for the django_fsm.signals.post_transition signal and creates a new record for each transition.

To query the log:

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

Disabling logging for specific models

By default transitions get recorded for all models. Logging can be disabled for specific models by adding their fully qualified name to DJANGO_FSM_LOG_IGNORED_MODELS.

DJANGO_FSM_LOG_IGNORED_MODELS = ('poll.models.Vote',)

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 this easy:

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

With this the transition gets logged when the by kwarg is present.

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

Admin integration

There is an InlineForm available that can be used to display the history of changes.

To use it expand your own AdminModel by adding StateLogInline to its inlines:

from django.contrib import admin
from django_fsm_log.admin import StateLogInline


@admin.register(FSMModel)
class FSMModelAdmin(admin.ModelAdmin):
    inlines = [StateLogInline]

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