django-migration-fixture

App to easily turn initial_data.* fixtures into Django 1.7 data migrations.

This is useful if you have a legacy project you are migration to Django 1.7+ which contains initial_data.* files that you rely upon.

Essentially it leaves the initial_data.* file in place and generates a data migration - as outlined in the docs.

Install

pip install django-migration-fixture

Then add django_migration_fixture to your INSTALLED_APPS.

INSTALLED_APPS += (
	'django_migration_fixture',
)

Usage

Simplest method is to simply call the create_initial_data_fixtures management command.

./manage.py create_initial_data_fixtures

The management command will automatically look for initial_data.* files in your list of INSTALLED_APPS and for each file found creates a data migration, similar to the following;

# -*- coding: utf-8 -*-
from __future__ import unicode_literals
from django.db import models, migrations
from django_migration_fixture import fixture
import myapp

class Migration(migrations.Migration):

	operations = [
		migrations.RunPython(**fixture(myapp, 'initial_data.yaml'))
	]

From this point it's just a matter of running migrate to apply your data migrations.

Note that this solution also supports rolling back your migration (by deleting using primary key) - thus if you don't want your data removed when doing a rollback you should fake.

API

fixture(app, fixtures, fixtures_dir='fixtures', raise_does_not_exist=False)

• app is a Django app that contains your fixtures
• fixtures can take either a string or a list of fixture files. The extension is used as the format supplied to django.core.serializers.deserialize
• fixtures_dir is the directory inside your app that contains the fixtures
• ignore_does_not_exist if set to True then django_migration_fixture.FixtureObjectDoesNotExist is raised if when attempting a rollback the object in the fixture does not exist.

Essentially fixture() returns a dict containing the keys 'code' and 'reverse_code' which attempt to apply your fixture and rollback your fixture, respectively.

Inspiration

While attempting to migrate a large Django project to 1.7 I came across an issue which caused me to create Django ticket 24023.

The project has a lot of fixtures that ensure a baseline state and converting them to code isn't really ideal, thus this project.

That issue has since been closed as a duplicate of ticket 23699 which itself has been closed and released in Django 1.7.2.

Needless to say, you may still need to create data migrations for your initial_data.* files, regardless of the issue I came across.

Author

Alex Hayes [email protected]