Welcome to Django Management Commands 👋

License: GNU General Public License v2.0 Version Python version PyPi version PyPi downloads

A Django management commands to help on migrations deployment rollbacks

Getting Started

This is a fork of Jc2k's work, where I've made small fixes, build and distribuite as a pypi package

The idea here is that if you know which migrations were in version 2.0.3 of your project and which were in version 2.0.4 then setA - setB gives you the list of migrations you need to undo. See Design Implementation document.

Prerequisites

  • Python >= 3.7
  • Django >= 2.2

Install

pip install django-migrations-mgmt

Usage

  • Add to django settings.py ```python INSTALLED_APPS = [ … ‘migrations_mgmt_cmds', … ] …

    Inform the class' path that handle storage's backend

    MIGRATIONS_RELEASES_STORAGE = ‘storages.backends.s3boto.S3BotoStorage'

Inform the function's path that handle storage's backend sorting method.

This is optional and should be a called for parameter key of sorted function.

MIGRATIONS_RELEASES_SORTING = ‘migrations_mgmt_cmds.management.commands.release_management.default_sort_date' …


- Create a migration release
```sh
python manage.py migrations_release --release v0.1
  • Check the release JSON file in your storage backend 
    ls
v0.1.json
  • Create a new migration ```sh python manage.py makemigrations Migrations for ‘sample_app': sample_app/migrations/0002_choice.py
    • Create model Choice ```
  • Execute pending migrations 
    python manage.py migrate
Operations to perform:
Apply all migrations: admin, auth, contenttypes, sample_app, sessions
Running migrations:
Applying sample_app.0002_choice... OK
  • Rollback the last applied migration 
    python manage.py migrations_rollback --release v0.1
Operations to perform:
Revert sample_app 0002_choice
Running migrations:
Rendering model states... DONE
Unapplying sample_app.0002_choice... OK
  • Check applied migrations 
    python manage.py showmigrations

Important Notes

Storage's Backend

The storage's backend to be used can be informed passing a class' path to the setting MIGRATIONS_RELEASES_STORAGE, in case it isn't informed, the value set-up at Django's setting DEFAULT_FILE_STORAGE will be used instead.

You should inform the path as python package, e.g. 'path.Classname'

Command release_management

This extension introduce a command to allow for displaying, disabling or deleting the release files available in the storage's backend:

# Display list of ordered release files with extension .json
python manage.py release_management --display-list

# Display last created file with extension .json
python manage.py release_management --display-last

# Delete a file informed by path from storage
python manage.py release_management --delete-release=<file's path in storage>

# Rename a release file informed by path from storage, appending `.disabled` to its filename. 
python manage.py release_management --disable-release=<release file's path in storage>

Known Issues

It's quite common to change the database level constraints - for example to suddenly allow NULL data - which you'll almost certainly end up with data that doesn't satisfy this constraint, and consequenctly any attempt to revert will fail. Similar problems existing when changing the size of a field.

So relying on this as a strategy for backing our changes is risky! More testing should be added.

Recomendations & Tips

To avoid the rollback issues mentioned above please check the Django Migrations Good Practices documentation

Documentation

Contributing

Contributions, issues and feature requests are welcome!

License

Copyright © 2021 Italo Santos.

This project is GNU General Public License v2.0 licensed.

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Author

👤 Italo Santos

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