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A Django app to track changes to a model field. For Python 2.7/3.4+ and Django 1.11/2.0+.
Other similar apps are django-reversion <https://github.com/etianen/django-reversion>
and django-simple-history <https://github.com/treyhunner/django-simple-history>
, which track all model fields.
+------------------------+----------------------+------------------+----------------------------------+
| Project | django-field-history | django-reversion | django-simple-history |
+------------------------+----------------------+------------------+----------------------------------+
| Admin Integration | N/A | Yes | Yes |
+------------------------+----------------------+------------------+----------------------------------+
| All/Some fields | Some | Some | All |
+------------------------+----------------------+------------------+----------------------------------+
| Object History | No | Yes | Yes |
+------------------------+----------------------+------------------+----------------------------------+
| Model History | N/A | No | Yes |
+------------------------+----------------------+------------------+----------------------------------+
| Multi-object Revisions | N/A | Yes | No |
+------------------------+----------------------+------------------+----------------------------------+
| Extra Model Manager | Yes | No | Yes |
+------------------------+----------------------+------------------+----------------------------------+
| Model Registry | No | Yes | No |
+------------------------+----------------------+------------------+----------------------------------+
| Django View Helpers | No | Yes | No |
+------------------------+----------------------+------------------+----------------------------------+
| Manager Helper Methods | N/A | Yes | Yes (as_of
, most_recent
) |
+------------------------+----------------------+------------------+----------------------------------+
| MySQL Support | Extra config | Complete | Complete |
+------------------------+----------------------+------------------+----------------------------------+
The full documentation is at https://django-field-history.readthedocs.io.
ManyToManyField
).Install django-field-history::
pip install django-field-history
Be sure to put it in INSTALLED_APPS.
.. code-block:: python
INSTALLED_APPS = [
# other apps...
'field_history',
]
Then add it to your models.
.. code-block:: python
from field_history.tracker import FieldHistoryTracker
class PizzaOrder(models.Model):
STATUS_CHOICES = (
('ORDERED', 'Ordered'),
('COOKING', 'Cooking'),
('COMPLETE', 'Complete'),
)
status = models.CharField(max_length=64, choices=STATUS_CHOICES)
field_history = FieldHistoryTracker(['status'])
Now each time you change the order's status field information about that change will be stored in the database.
.. code-block:: python
from field_history.models import FieldHistory
# No FieldHistory objects yet
assert FieldHistory.objects.count() == 0
# Creating an object will make one
pizza_order = PizzaOrder.objects.create(status='ORDERED')
assert FieldHistory.objects.count() == 1
# This object has some fields on it
history = FieldHistory.objects.get()
assert history.object == pizza_order
assert history.field_name == 'status'
assert history.field_value == 'ORDERED'
assert history.date_created is not None
# You can query FieldHistory using the get_{field_name}_history()
# method added to your model
histories = pizza_order.get_status_history()
assert list(FieldHistory.objects.all()) == list(histories)
# Or using the custom FieldHistory manager
histories2 = FieldHistory.objects.get_for_model_and_field(pizza_order, 'status')
assert list(histories) == list(histories2)
# Updating that particular field creates a new FieldHistory
pizza_order.status = 'COOKING'
pizza_order.save()
assert FieldHistory.objects.count() == 2
updated_history = histories.latest()
assert updated_history.object == pizza_order
assert updated_history.field_name == 'status'
assert updated_history.field_value == 'COOKING'
assert updated_history.date_created is not None
django-field-history comes with a few management commands.
createinitialfieldhistory +++++++++++++++++++++++++
This command will inspect all of the models in your application and create FieldHistory
objects for the models that have a FieldHistoryTracker
. Run this the first time you install django-field-history.
::
python manage.py createinitialfieldhistory
renamefieldhistory ++++++++++++++++++
Use this command after changing a model field name of a field you track with FieldHistoryTracker
::
python manage.py renamefieldhistory --model=app_label.model_name --from_field=old_field_name --to_field=new_field_name
For instance, if you have this model:
.. code-block:: python
class Person(models.Model):
username = models.CharField(max_length=255)
field_history = FieldHistoryTracker(['username'])
And you change the username
field name to handle
:
.. code-block:: python
class Person(models.Model):
handle = models.CharField(max_length=255)
field_history = FieldHistoryTracker(['handle'])
You will need to also update the field_name
value in all FieldHistory
objects that point to this model::
python manage.py renamefieldhistory --model=myapp.Person --from_field=username --to_field=handle
There are two ways to store the user that changed your model field. The simplest way is to use the logged in user that made the request. To do this, add the FieldHistoryMiddleware
class to your MIDDLEWARE
setting.
.. code-block:: python
MIDDLEWARE = [
'django.contrib.sessions.middleware.SessionMiddleware',
'django.middleware.common.CommonMiddleware',
'django.contrib.auth.middleware.AuthenticationMiddleware',
'field_history.middleware.FieldHistoryMiddleware',
]
Alternatively, you can add a _field_history_user
property to the model that has fields you are tracking. This property should return the user you would like stored on FieldHistory
when your field is updated.
.. code-block:: python
class Pizza(models.Model):
name = models.CharField(max_length=255)
updated_by = models.ForeignKey('auth.User')
field_history = FieldHistoryTracker(['name'])
@property
def _field_history_user(self):
return self.updated_by
If you're using MySQL, the default configuration will throw an exception when you run migrations. (By default, FieldHistory.object_id
is implemented as a TextField
for flexibility, but indexed columns in MySQL InnoDB tables may be a maximum of 767 bytes.) To fix this, you can set FIELD_HISTORY_OBJECT_ID_TYPE
in settings.py to override the default field type with one that meets MySQL's constraints. FIELD_HISTORY_OBJECT_ID_TYPE
may be set to either:
(field_class, kwargs)
, where field_class
is a Django model field class and kwargs
is a dict of arguments to pass to the field class constructor.To approximate the default behavior for Postgres when using MySQL, configure object_id
to use a CharField
by adding the following to settings.py:
.. code-block:: python
from django.db import models
FIELD_HISTORY_OBJECT_ID_TYPE = (models.CharField, {'max_length': 100})
FIELD_HISTORY_OBJECT_ID_TYPE
also allows you to use a field type that's more efficient for your use case, even if you're using Postgres (or a similarly unconstrained database). For example, if you always let Django auto-create an id
field (implemented internally as an AutoField
), setting FIELD_HISTORY_OBJECT_ID_TYPE
to IntegerField
will result in efficiency gains (both in time and space). This would look like:
.. code-block:: python
from django.db import models
FIELD_HISTORY_OBJECT_ID_TYPE = models.IntegerField
Does the code actually work?
::
source <YOURVIRTUALENV>/bin/activate
(myenv) $ pip install -r requirements-test.txt
(myenv) $ python runtests.py