django-simple-history

django-simple-history stores Django model state on every create/update/delete.

Documentation

Quick Start

Install

This package is available on PyPI and Crate.io.

Install from PyPI with pip:

$ pip install django-simple-history

Configure

Settings

Add simple_history to your INSTALLED_APPS

INSTALLED_APPS = [
    # ...
    'simple_history',
]

The historical models can track who made each change. To populate the history user automatically you can add middleware to your Django settings:

MIDDLEWARE_CLASSES = [
    # ...
    'simple_history.middleware.HistoryRequestMiddleware',
]

If you do not want to use the middleware, you can explicitly indicate the user making the change as documented in recording_user.

Models

To track history for a model, create an instance of simple_history.models.HistoricalRecords on the model.

An example for tracking changes on the Poll and Choice models in the Django tutorial:

from django.db import models
from simple_history.models import HistoricalRecords

class Poll(models.Model):
    question = models.CharField(max_length=200)
    pub_date = models.DateTimeField('date published')
    history = HistoricalRecords()

class Choice(models.Model):
    poll = models.ForeignKey(Poll)
    choice_text = models.CharField(max_length=200)
    votes = models.IntegerField(default=0)
    history = HistoricalRecords()

Now all changes to Poll and Choice model instances will be tracked in the database.

Existing Projects

For existing projects, you can call the populate command to generate an initial change for preexisting model instances:

$ python manage.py populate_history --auto

Integration with Django Admin

To allow viewing previous model versions on the Django admin site, inherit from the simple_history.admin.SimpleHistoryAdmin class when registering your model with the admin site.

This will replace the history object page on the admin site and allow viewing and reverting to previous model versions. Changes made in admin change forms will also accurately note the user who made the change.

_images/1_poll_history.png

Clicking on an object presents the option to revert to that version of the object.

_images/2_revert.png

(The object is reverted to the selected state)

_images/3_poll_reverted.png

Reversions like this are added to the history.

_images/4_history_after_poll_reverted.png

An example of admin integration for the Poll and Choice models:

from django.contrib import admin
from simple_history.admin import SimpleHistoryAdmin
from .models import Poll, Choice

admin.site.register(Poll, SimpleHistoryAdmin)
admin.site.register(Choice, SimpleHistoryAdmin)

Changing a history-tracked model from the admin interface will automatically record the user who made the change (see recording_user).

Querying history

Querying history on a model instance

The HistoricalRecords object on a model instance can be used in the same way as a model manager:

>>> from polls.models import Poll, Choice
>>> from datetime import datetime
>>> poll = Poll.objects.create(question="what's up?", pub_date=datetime.now())
>>>
>>> poll.history.all()
[<HistoricalPoll: Poll object as of 2010-10-25 18:03:29.855689>]

Whenever a model instance is saved a new historical record is created:

>>> poll.pub_date = datetime(2007, 4, 1, 0, 0)
>>> poll.save()
>>> poll.history.all()
[<HistoricalPoll: Poll object as of 2010-10-25 18:04:13.814128>, <HistoricalPoll: Poll object as of 2010-10-25 18:03:29.855689>]
Querying history on a model class

Historical records for all instances of a model can be queried by using the HistoricalRecords manager on the model class. For example historical records for all Choice instances can be queried by using the manager on the Choice model class:

>>> choice1 = poll.choice_set.create(choice_text='Not Much', votes=0)
>>> choice2 = poll.choice_set.create(choice_text='The sky', votes=0)
>>>
>>> Choice.history
<simple_history.manager.HistoryManager object at 0x1cc4290>
>>> Choice.history.all()
[<HistoricalChoice: Choice object as of 2010-10-25 18:05:12.183340>, <HistoricalChoice: Choice object as of 2010-10-25 18:04:59.047351>]

Common Issues

  • fields.E300:

    ERRORS:
custom_user.HistoricalCustomUser.history_user: (fields.E300) Field defines a relation with model 'custom_user.CustomUser', which is either not installed, or is abstract.

    Use register() to track changes to the custom user model instead of setting HistoricalRecords on the model directly. See History for a Third-Party Model.

    The reason for this, is that unfortunately HistoricalRecords cannot be set directly on a swapped user model because of the user foreign key to track the user making changes.

  • HistoricalRecords is not inherited

    Allowing HistoricalRecords to be inherited from abstract models or other parents is a feature we would love to add. The current contributors do not have a need for that feature at this point, and need some help understanding how this feature should be completed. Current work is in #112.

Advanced Usage

Database Migrations

By default, Historical models live in the same app as the model they track. Historical models are tracked by migrations in the same way as any other model. Whenever the original model changes, the historical model will change also.

Therefore tracking historical models with migrations should work automatically.

Locating past model instance

Two extra methods are provided for locating previous models instances on historical record model managers.

as_of

This method will return an instance of the model as it would have existed at the provided date and time.

>>> from datetime import datetime
>>> poll.history.as_of(datetime(2010, 10, 25, 18, 4, 0))
<Poll: Poll object as of 2010-10-25 18:03:29.855689>
>>> poll.history.as_of(datetime(2010, 10, 25, 18, 5, 0))
<Poll: Poll object as of 2010-10-25 18:04:13.814128>
most_recent

This method will return the most recent copy of the model available in the model history.

>>> from datetime import datetime
>>> poll.history.most_recent()
<Poll: Poll object as of 2010-10-25 18:04:13.814128>

History for a Third-Party Model

To track history for a model you didn’t create, use the simple_history.register utility. You can use this to track models from third-party apps you don’t have control over. Here’s an example of using simple_history.register to history-track the User model from the django.contrib.auth app:

from simple_history import register
from django.contrib.auth.models import User

register(User)

Recording Which User Changed a Model

To denote which user changed a model, assign a _history_user attribute on your model.

For example if you have a changed_by field on your model that records which user last changed the model, you could create a _history_user property referencing the changed_by field:

from django.db import models
from simple_history.models import HistoricalRecords

class Poll(models.Model):
    question = models.CharField(max_length=200)
    pub_date = models.DateTimeField('date published')
    changed_by = models.ForeignKey('auth.User')
    history = HistoricalRecords()

    @property
    def _history_user(self):
        return self.changed_by

    @_history_user.setter
    def _history_user(self, value):
        self.changed_by = value

Admin integration requires that you use a _history_user.setter attribute with your custom _history_user property (see Integration with Django Admin).

Custom history_date

You’re able to set a custom history_date attribute for the historical record, by defining the property _history_date in your model. That’s helpful if you want to add versions to your model, which happened before the current model version, e.g. when batch importing historical data. The content of the property _history_date has to be a datetime-object, but setting the value of the property to a DateTimeField, which is already defined in the model, will work too.

from django.db import models
from simple_history.models import HistoricalRecords

class Poll(models.Model):
    question = models.CharField(max_length=200)
    pub_date = models.DateTimeField('date published')
    changed_by = models.ForeignKey('auth.User')
    history = HistoricalRecords()
    __history_date = None

    @property
    def _history_date(self):
        return self.__history_date

    @_history_date.setter
    def _history_date(self, value):
        self.__history_date = value

from datetime import datetime
from models import Poll

my_poll = Poll(question="what's up?")
my_poll._history_date = datetime.now()
my_poll.save()

Change Base Class of HistoricalRecord Models

To change the auto-generated HistoricalRecord models base class from models.Model, pass in the abstract class in a list to bases.

class RoutableModel(models.Model):
    class Meta:
        abstract = True


class Poll(models.Model):
    question = models.CharField(max_length=200)
    pub_date = models.DateTimeField('date published')
    changed_by = models.ForeignKey('auth.User')
    history = HistoricalRecords(bases=[RoutableModel])

Code

Code and issue tracker: https://github.com/treyhunner/django-simple-history

Pull requests are welcome.

Changes

1.6.3 (2015-07-30)

  • Respect to_field and db_column parameters (gh-182)

1.6.2 (2015-07-04)

  • Use app loading system and fix deprecation warnings on Django 1.8 (gh-172)
  • Update Landscape configuration

1.6.1 (2015-04-21)

  • Fix OneToOneField transformation for historical models (gh-166)
  • Disable cascading deletes from related models to historical models
  • Fix restoring historical instances with missing one-to-one relations (gh-162)

1.6.0 (2015-04-16)

  • Add support for Django 1.8+
  • Deprecated use of CustomForeignKeyField (to be removed)
  • Remove default reverse accessor to auth.User for historical models (gh-121)

1.5.4 (2015-01-03)

  • Fix a bug when models have a ForeignKey with primary_key=True
  • Do NOT delete the history elements when a user is deleted.
  • Add support for latest

1.5.3 (2014-11-18)

  • Fix migrations while using order_with_respsect_to (gh-140)
  • Fix migrations using south
  • Allow history accessor class to be overridden in register()

1.5.2 (2014-10-15)

  • Additional fix for migrations (gh-128)

1.5.1 (2014-10-13)

  • Removed some incompatibilities with non-default admin sites (gh-92)
  • Fixed error caused by HistoryRequestMiddleware during anonymous requests (gh-115 fixes gh-114)
  • Added workaround for clashing related historical accessors on User (gh-121)
  • Added support for MongoDB AutoField (gh-125)
  • Fixed CustomForeignKeyField errors with 1.7 migrations (gh-126 fixes gh-124)

1.5.0 (2014-08-17)

  • Extended availability of the as_of method to models as well as instances.
  • Allow history_user on historical objects to be set by middleware.
  • Fixed error that occurs when a foreign key is designated using just the name of the model.
  • Drop Django 1.3 support

1.4.0 (2014-06-29)

  • Fixed error that occurs when models have a foreign key pointing to a one to one field.
  • Fix bug when model verbose_name uses unicode (gh-76)
  • Allow non-integer foreign keys
  • Allow foreign keys referencing the name of the model as a string
  • Added the ability to specify a custom history_date
  • Note that simple_history should be added to INSTALLED_APPS (gh-94 fixes gh-69)
  • Properly handle primary key escaping in admin URLs (gh-96 fixes gh-81)
  • Add support for new app loading (Django 1.7+)
  • Allow specifying custom base classes for historical models (gh-98)

1.3.0 (2013-05-17)

  • Fixed bug when using django-simple-history on nested models package
  • Allow history table to be formatted correctly with django-admin-bootstrap
  • Disallow calling simple_history.register twice on the same model
  • Added Python 3 support
  • Added support for custom user model (Django 1.5+)

1.2.3 (2013-04-22)

  • Fixed packaging bug: added admin template files to PyPI package

1.2.1 (2013-04-22)

  • Added tests
  • Added history view/revert feature in admin interface
  • Various fixes and improvements

Oct 22, 2010

  • Merged setup.py from Klaas van Schelven - Thanks!

Feb 21, 2010

  • Initial project creation, with changes to support ForeignKey relations.