makemigrations.py 文件源码

def check_migrations():
    from django.db.migrations.autodetector import MigrationAutodetector
    from django.db.migrations.executor import MigrationExecutor
    from django.db.migrations.state import ProjectState

    changed = set()

    print("Checking {} migrations...".format(APP_NAME))
    for db in settings.DATABASES.keys():
        try:
            executor = MigrationExecutor(connections[db])
        except OperationalError as e:
            sys.exit(
                "Unable to check migrations due to database: {}".format(e)
            )

        autodetector = MigrationAutodetector(
            executor.loader.project_state(),
            ProjectState.from_apps(apps),
        )

        changed.update(
            autodetector.changes(graph=executor.loader.graph).keys()
        )

    if changed and APP_NAME in changed:
        sys.exit(
            "A migration file is missing. Please run "
            "`python makemigrations.py` to generate it."
        )
    else:
        print("All migration files present.")