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Quick Start

Install

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 HistoryRequestMiddleware to your Django settings:

MIDDLEWARE = [
    # ...
    '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 User Tracking.

Track History

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.

Track History for a Third-Party Model

To track history for a model you didn’t create, use the simple_history.register function. 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)

If you want to separate the migrations of the historical model into an app other than the third-party model’s app, you can set the app parameter in register. For instance, if you want the migrations to live in the migrations folder of the package you register the model in, you could do:

register(User, app=__package__)

Run Migrations

With your model changes in place, create and apply the database migrations:

$ python manage.py makemigrations
$ python manage.py migrate

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

By default, history rows are inserted in batches of 200. This can be changed if needed for large tables by using the --batchsize option, for example --batchsize 500.

What Now?

By adding HistoricalRecords to a model or registering a model using register, you automatically start tracking any create, update, or delete that occurs on that model. Now you can query the history programmatically and view the history in Django admin.

What is django-simple-history Doing Behind the Scenes?

If you tried the code above and ran the migrations on it, you’ll see the following tables in your database:

  • app_choice

  • app_historicalchoice

  • app_historicalpoll

  • app_poll

The two extra tables with historical prepended to their names are tables created by django-simple-history. These tables store every change that you make to their respective base tables. Every time a create, update, or delete occurs on Choice or Poll a new row is created in the historical table for that model including all of the fields in the instance of the base model, as well as other metadata:

  • history_user: the user that made the create/update/delete

  • history_date: the datetime at which the create/update/delete occurred

  • history_change_reason: the reason the create/update/delete occurred (null by default)

  • history_id: the primary key for the historical table (note the the base table’s primary key is not unique on the historical table since there are multiple versions of it on the historical table)

  • history_type: + for create, ~ for update, and - for delete

Now try saving an instance of Choice or Poll. Check the historical table to see that the history is being tracked.

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