django-migration-zero

Welcome to django-migration-zero - the holistic implementation of "migration zero" pattern for Django covering local changes and CI/CD pipeline adjustments.

This package implements the "migration zero" pattern to clean up your local migrations and provides convenient management commands to recreate your migration files and updating your migration history on your environments (like test or production systems).

• PyPI
• GitHub
• Full documentation
• Creator & Maintainer: Ambient Digital

Features

• Remove all existing local migration files and recreate them as initial migrations
• Configuration singleton in Django admin to prepare your clean-up deployment
• Management command for your pipeline to update Django's migration history table to reflect the changed migrations

Motivation

Working with any proper ORM will result in database changes which are reflected in migration files to update your different environment's database structure. These files are versioned in your repository and if you follow any of the most popular deployment approaches, they won't be needed when they are deployed on production. This means, they clutter your repo, might lead to merge conflicts in the future and will slow down your test setup.

Django's default way of handling this is called "squashing". This approach is covered broadly in the official documentation. The main drawback here is, that you have to take care of circular dependencies between models. Depending on your project's size, this can take a fair amount of time.

The main benefit of squashing migrations is, that the history stays intact, therefore it can be used for example in package which can be installed by anybody and you don't have control over their database.

If you are working on a "regular" application, you have full control over your data(bases) and once everything has been applied on the "last" system, typically production, the migrations are obsolete. To avoid spending much time on fixing squashed migrations you won't need, you can use the "migration zero" pattern. In a nutshell, this means:

• Delete all your local migration files
• Recreate initial migration files containing your current model state
• Fix the migration history on every of your environments

Installation

• Install the package via pip:

  pip install django-migration-zero

  or via pipenv:

  pipenv install django-migration-zero

• Add module to INSTALLED_APPS within the main django settings.py:

  INSTALLED_APPS = (
      ...
      'django_migration_zero',
  )
  

• Apply migrations by running:

  python ./manage.py migrate

• Add this block to your loggers in your main Django settings.py to show logs in your console.

LOGGING = {
    "loggers": {
        "django_migration_zero": {
            "handlers": ["console"],
            "level": "INFO",
            "propagate": True,
        },
    },
}

Contribute

Setup package for development

• Create a Python virtualenv and activate it
• Install "pip-tools" with pip install -U pip-tools
• Compile the requirements with pip-compile --extra dev, -o requirements.txt pyproject.toml --resolver=backtracking
• Sync the dependencies with your virtualenv with pip-sync

Add functionality

• Create a new branch for your feature
• Change the dependency in your requirements.txt to a local (editable) one that points to your local file system: -e /Users/workspace/django-migration-zero or via pip pip install -e /Users/workspace/django-migration-zero
• Ensure the code passes the tests
• Create a pull request

Run tests

• Run tests

  pytest --ds settings tests
  

• Check coverage

  coverage run -m pytest --ds settings tests
  coverage report -m
  

Git hooks (via pre-commit)

We use pre-push hooks to ensure that only linted code reaches our remote repository and pipelines aren't triggered in vain.

To enable the configured pre-push hooks, you need to install pre-commit and run once:

pre-commit install -t pre-push -t pre-commit --install-hooks

This will permanently install the git hooks for both, frontend and backend, in your local .git/hooks folder. The hooks are configured in the .pre-commit-config.yaml.

You can check whether hooks work as intended using the run command:

pre-commit run [hook-id] [options]

Example: run single hook

pre-commit run ruff --all-files --hook-stage push

Example: run all hooks of pre-push stage

pre-commit run --all-files --hook-stage push

Update documentation

• To build the documentation, run: sphinx-build docs/ docs/_build/html/.
• Open docs/_build/html/index.html to see the documentation.

Translation files

If you have added custom text, make sure to wrap it in _() where _ is gettext_lazy (from django.utils.translation import gettext_lazy as _).

How to create translation file:

• Navigate to django-migration-zero
• python manage.py makemessages -l de
• Have a look at the new/changed files within django_migration_zero/locale

How to compile translation files:

• Navigate to django-migration-zero
• python manage.py compilemessages
• Have a look at the new/changed files within django_migration_zero/locale

Publish to ReadTheDocs.io

• Fetch the latest changes in GitHub mirror and push them
• Trigger new build at ReadTheDocs.io (follow instructions in admin panel at RTD) if the GitHub webhook is not yet set up.

Publish to PyPi

• Update documentation about new/changed functionality

• Update the Changelog

• Increment version in main __init__.py

• Create pull request / merge to master

• This project uses the flit package to publish to PyPI. Thus publishing should be as easy as running:

  flit publish
  

  To publish to TestPyPI use the following ensure that you have set up your .pypirc as shown here and use the following command:

  flit publish --repository testpypi
  

Maintenance

Please note that this package supports the ambient-package-update. So you don't have to worry about the maintenance of this package. All important configuration and setup files are being rendered by this updater. It works similar to well-known updaters like pyupgrade or django-upgrade.

To run an update, refer to the documentation page of the "ambient-package-update".