django-migrate-project 0.2.0

Django management commands for project-wide (editable) migrations.

Django management commands for project-wide (editable) migrations.

Overview

The django-migrate-project app aims to add management commands to make running full project migrations more sane and controllable. The concept is pretty simple: first collect any unapplied migrations into per-app migration files, then review and modify as need be, and finally apply the migrations.

By staging and consolidating unapplied migrations in a way that they can be edited and reviewed before applying, more confidence is gained that a rogue migration won’t damage production tables. The collected and consolidated migrations are listed as replacements for the individual app migrations they represent so once they have been applied everything is in the same state as if the individual app migrations has been applied via ‘migrate’.

Requirements

Requires Django 1.7+ and as such Python 2.7+ as well

Installation

Simply use pip to install:

$ pip install django-migrate-project

To be of any use django-migrate-project must be added to the Django project via INSTALLED_APPS in the project settings.py file:

INSTALLED_APPS = (
    ...
    'django_migrate_project',
    ...
)

Usage

Two new management commands provide the core functionality. To gather up any unapplied migrations for the project simply run:

$ python manage.py collectmigrations

The default collection location is BASE_DIR/pending_migrations. If the project’s settings.py does not have a BASE_DIR then a directory path must be provided using the --output-dir option.

The collected migrations are grouped per-app and have the filename format of <app_label>_project.py. These files can be edited to taste in order to change the migration, the only important bit is to keep the replaces and dependencies fields in the migration the same, as those allow the bookkeeping to be kept accurate.

Collected migrations are applied via:

$ python manage.py applymigrations

The default directory path is used again if possible, otherwise the path must be provided via the --input-dir option.

Finally, migrations can be unapplied easily as well, returning the migration state to what it was before by running:

$ python manage.py applymigrations --unapply

Experimental

Starting with v0.2.0 there’s also the capability to generate project-level migrations as a way to capture monkey-patched models and other changes that shouldn’t create migrations in a third-party app.

To use this functionality, first create a top-level migrations directory with a __init__.py file to make it a Python package. Then run the following command to create any new project-level migrations (changes not present in third-party app migrations):

$ python manage.py makeprojectmigrations

Assuming there are any migrations to generate, the top-level migrations directory should now be populated and you can migrate the project using:

$ python manage.py migrateproject

As with the applymigrations command, migrateproject also has an easy unapply functionality:

$ python manage.py migrateproject --unapply

While this functionality is well covered by tests it will remain ‘experimental’ until it gets a bit more real world use.

Contributing

Contributions are welcome, just create a pull request or issue on the GitHub repository for the project.