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django-history-triggers

django-history-triggers is a Django application for installing database triggers that automatically record inserts, updates, and deletes to model tables.

Requirements

  • Django 3.2+
  • PostgreSQL or SQLite database

Installation

pip install django-history-triggers

Quick Start

  1. Add history to your INSTALLED_APPS setting and migrate your database.
  2. Add history.middleware.HistoryMiddleware to the end of your MIDDLEWARE setting.
  3. Run manage.py triggers enable to install the trigger functions, or manage.py triggers disable to uninstall them. Neither will clear existing history data -- add a --clear option to do that.

Settings

  • HISTORY_MODEL (default: "history.ObjectHistory")
  • HISTORY_IGNORE_APPS (default: ["admin", "contenttypes", "sessions"])
  • HISTORY_IGNORE_MODELS (default [] - should be lowercase app_label.model_name)
  • HISTORY_MIDDLEWARE_IGNORE (default: [])
  • HISTORY_FILTER (default: "history.utils.default_filter")
  • HISTORY_REQUEST_CONTEXT (default: "history.utils.get_request_context")
  • HISTORY_ADMIN_ENABLED (default: True)
  • HISTORY_INCLUDE_UNMANAGED (default: True)

History Sessions

History is recorded within "sessions" that you can manage manually, either outside of a web request context, or in place of or in addition to the included middleware. The easiest way to manage a history session is via a context manager:

from history import get_backend

def api_view(request):
    # You can pass extra fields to be stored for all history within a session.
    with get_backend().session(user=request.user, path=request.path):
        # All history inside here will have the same session_id and session_date.
        ...

Starting in 3.4.2, you can also "pause" history recording within a session:

 with get_backend().session() as session:
     Model.objects.create(name="This history is recorded")
     with session.paused():
        Model.objects.create(name="This history is NOT recorded")
     Model.objects.create(name="This history is also recorded")

Custom History Model

The default history.ObjectHistory model is swappable by changing the HISTORY_MODEL setting. If you need to define your own object history model (usually for tracking custom fields or non-standard user info), be sure to inherit from history.models.AbstractObjectHistory. If at all possible, do this early on to avoid problems with migrations when changing HISTORY_MODEL after the initial migration.

Filtering History

The HISTORY_FILTER setting allows you to fully customize which fields (or even whole models) should be included in or excluded from history. It is implemented as a callable that takes three parameters:

  • The django.db.models.Model class being filtered
  • The django.db.models.fields.Field instance in question
  • The history.models.TriggerType being created

The filter should return True if the field should be included, and False if it should be excluded. The default implementation (history.utils.default_filter) simply includes any field except BinaryFields:

def default_filter(model, field, trigger_type):
    return not isinstance(field, models.BinaryField)

Returning False for all fields of any given model has the effect of not tracking history for that model:

def filter_sensitive(model, field, trigger_type):
    return not issubclass(model, SensitiveDataModel)

Similarly, if you (for example) only wanted to record history for UPDATE statements:

def updates_only(model, field, trigger_type):
    return trigger_type == TriggerType.UPDATE

Management Commands

By default django-history-triggers does not override any of Django's management commands that may perform database operations, such as loaddata or migrate. If you need to run these commands with history triggers enabled, you can include the following apps in your INSTALLED_APPS setting:

  • history.contrib.loaddata
  • history.contrib.migrate

The HISTORY_LOADDATA_CONTEXT and HISTORY_MIGRATE_CONTEXT settings control the history session context for the respective command, for example:

HISTORY_MIGRATE_CONTEXT = {"user": "system"}