django-migration-linter 3.0.1

Detect backward incompatible migrations for your django project

Django migration linter

Detect backward incompatible migrations for your Django project. It will save you time by making sure migrations will not break with a older codebase.

Quick installation

pip install django-migration-linter

And add the migration linter your INSTALLED_APPS:

    INSTALLED_APPS = [
        ...,
        "django_migration_linter",
        ...,
    ]

Usage example

$ python manage.py lintmigrations

(app_add_not_null_column, 0001_create_table)... OK
(app_add_not_null_column, 0002_add_new_not_null_field)... ERR
        NOT NULL constraint on columns
(app_drop_table, 0001_initial)... OK
(app_drop_table, 0002_delete_a)... ERR
        DROPPING table
(app_ignore_migration, 0001_initial)... OK
(app_ignore_migration, 0002_ignore_migration)... IGNORE
(app_rename_table, 0001_initial)... OK
(app_rename_table, 0002_auto_20190414_1500)... ERR
        RENAMING tables

*** Summary ***
Valid migrations: 4/8
Erroneous migrations: 3/8
Migrations with warnings: 0/8
Ignored migrations: 1/8

The linter analysed all migrations from the Django project. It found 3 migrations that are doing backward incompatible operations and 1 that is explicitly ignored. The list of incompatibilities that the linter analyses can be found at docs/incompatibilities.md.

More advanced usages of the linter and options can be found at docs/usage.md.

Integration

One can either integrate the linter in the CI and the lintmigrations command, or detect incompatibilities during generation with

$ python manage.py makemigrations --lint

Migrations for 'app_correct':
  tests/test_project/app_correct/migrations/0003_a_column.py
    - Add field column to a
Linting for 'app_correct':
(app_correct, 0003_a_column)... ERR
        NOT NULL constraint on columns

The migration linter detected that this migration is not be backward compatible.
- If you keep the migration, you will want to fix the issue or ignore the migration.
- By default, the newly created migration file will be deleted.
Do you want to keep the migration? [y/N]
[...]
Deleted tests/test_project/app_correct/migrations/0003_a_column.py

The linter found that the newly created migration is not backward compatible and deletes the files. This behaviour can be the default of the makemigrations command through the MIGRATION_LINTER_OVERRIDE_MAKEMIGRATIONS Django settings. Find out more about the makemigrations command at docs/makemigrations.md.

More information

Please find more documentation generally in the docs/ folder.

Some implementation details can found in the ./docs/internals/ folder.

Blog post

• Keeping Django database migrations backward compatible
• Django and its default values

They talk about the linter

• Django News
• wemake-django-template
• Testing Django migrations on sobolevn's blog

Related

• django-test-migrations - Test django schema and data migrations, including migrations' order and best practices.

License

django-migration-linter is released under the Apache 2.0 License.

Maintained by David Wobrock