__main__.py 文件源码

def load_migration_nodes():
    nodes = {None: MigrationRouteHead()}
    for path in _migrations_dir_path.iterdir():
        if not _migration_filename_pattern.match(path.name):
            continue
        module = importlib.import_module(f'quizzler.migrations.{path.stem}')
        nodes[path.stem] = MigrationNode(path.stem, module)

    # Fill linked-list info.
    for name, node in nodes.items():
        if name is None:
            continue
        prev_name = node.module.previous
        prev_node = nodes[prev_name]
        if prev_node.next is not None:
            raise MigrationRouteConflict(
                f'{name} and {prev_node.next.name} '
                f'both specify previous = {prev_name!r}',
            )
        prev_node.next = node
        node.prev = prev_node

    return nodes