Git post-checkout hook to detect applied missing migrations in Django

README.md

To install this hook

echo "#\!/bin/bash\npython manage.py check_applied_missing_migrations\n" > .git/hooks/post-checkout
chmod + .git/hooks/post-checkout

check_applied_missing_migrations.py

from django.core.management import BaseCommand
from django.db import connection
from django.db.migrations.executor import MigrationExecutor


class Command(BaseCommand):
    def handle(self, *args, **options):
        # Work out which apps have migrations and which do not
        executor = MigrationExecutor(connection)
        applied_missing_migrations = set(executor.loader.applied_migrations) - set(
            executor.loader.disk_migrations
        )
        if applied_missing_migrations:
            self.stderr.write(
                "Warning: you have applied migrations that no longer exist:"
            )
            for app_label, migration_name in applied_missing_migrations:
                self.stderr.write(
                    f" - {app_label}: {migration_name}", style_func=self.style.WARNING
                )