Django Cleanup

Features

The django-cleanup app automatically deletes files for FileField, ImageField and subclasses. When a FileField's value is changed and the model is saved, the old file is deleted. When a model that has a FileField is deleted, the file is also deleted. A file that is set as the FileField's default value will not be deleted.

Compatibility

Django 3.2, 4.0, 4.1 (See Django Supported Versions)
Python 3.6+
Compatible with sorl-thumbnail
Compatible with easy-thumbnail

How does it work?

In order to track changes of a FileField and facilitate file deletions, django-cleanup connects post_init, pre_save, post_save and post_delete signals to signal handlers for each INSTALLED_APPS model that has a FileField. In order to tell whether or not a FileField's value has changed a local cache of original values is kept on the model instance. If a condition is detected that should result in a file deletion, a function to delete the file is setup and inserted into the commit phase of the current transaction.

Warning! Please be aware of the known limitations documented below!

Installation

pip install django-cleanup

Configuration

Add django_cleanup to the bottom of INSTALLED_APPS in settings.py

INSTALLED_APPS = (
    ...,
    'django_cleanup.apps.CleanupConfig',
)

That is all, no other configuration is necessary.

Note: Order of INSTALLED_APPS is important. To ensure that exceptions inside other apps' signal handlers do not affect the integrity of file deletions within transactions, django_cleanup should be placed last in INSTALLED_APPS.

Troubleshooting

If you notice that django-cleanup is not removing files when expected, check that your models are being properly loaded:

You must define or import all models in your application's models.py or models/__init__.py. Otherwise, the application registry may not be fully populated at this point, which could cause the ORM to malfunction.

If your models are not loaded, django-cleanup will not be able to discover their FileField's.

You can check if your Model is loaded by using

from django.apps import apps
apps.get_models()

Known limitations

Database should support transactions

If you are using a database that does not support transactions you may lose files if a transaction will rollback at the right instance. This outcome is mitigated by our use of post_save and post_delete signals, and by following the recommended configuration in this README. This outcome will still occur if there are signals registered after app initialization and there are exceptions when those signals are handled. In this case, the old file will be lost and the new file will not be referenced in a model, though the new file will likely still exist on disk. If you are concerned about this behavior you will need another solution for old file deletion in your project.

File referenced by multiple model instances

This app is designed with the assumption that each file is referenced only once. If you are sharing a file over two or more model instances you will not have the desired functionality. Be cautious of copying model instances, as this will cause a file to be shared by more than one instance. If you want to reference a file from multiple models add a level of indirection. That is, use a separate file model that is referenced from other models through a foreign key. There are many file management apps already available in the django ecosystem that fulfill this behavior.

Advanced

This section contains additional functionality that can be used to interact with django-cleanup for special cases.

Signals

To facilitate interactions with other django apps django-cleanup sends the following signals which can be imported from django_cleanup.signals:

cleanup_pre_delete: just before a file is deleted. Passes a file keyword argument.
cleanup_post_delete: just after a file is deleted. Passes a file keyword argument.

Signals example for sorl.thumbnail:

from django_cleanup.signals import cleanup_pre_delete
from sorl.thumbnail import delete

def sorl_delete(**kwargs):
    delete(kwargs['file'])

cleanup_pre_delete.connect(sorl_delete)

Refresh the cache

There have been rare cases where the cache would need to be refreshed. To do so the django_cleanup.cleanup.refresh method can be used:

from django_cleanup import cleanup

cleanup.refresh(model_instance)

Ignore cleanup for a specific model

To ignore a model and not have cleanup performed when the model is deleted or its files change, use the ignore decorator to mark that model:

from django_cleanup import cleanup

@cleanup.ignore
class MyModel(models.Model):
    image = models.FileField()

Only cleanup selected models

If you have many models to ignore, or if you prefer to be explicit about what models are selected, you can change the mode of django-cleanup to "select mode" by using the select mode app config. In your INSTALLED_APPS setting you will replace 'django_cleanup.apps.CleanupConfig' with 'django_cleanup.apps.CleanupSelectedConfig'. Then use the select decorator to mark a model for cleanup:

from django_cleanup import cleanup

@cleanup.select
class MyModel(models.Model):
    image = models.FileField()

How to run tests

Install, setup and use pyenv to install all the required versions of cPython (see the tox.ini).

Setup pyenv to have all versions of python activated within your local django-cleanup repository. Ensuring that the python 3.10 that was installed is first priority.

Install tox on python 3.10 and run the tox command from your local django-cleanup repository.

How to write tests

This app requires the use of django.test.TransactionTestCase when writing tests.

For details on why this is required see here:

Django's TestCase class wraps each test in a transaction and rolls back that transaction after each test, in order to provide test isolation. This means that no transaction is ever actually committed, thus your on_commit() callbacks will never be run. If you need to test the results of an on_commit() callback, use a TransactionTestCase instead.

License

django-cleanup is free software under terms of the:

MIT License

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

un1t/django-cleanup

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