from pathlib import Path
from typing import Dict

def make_meta_func(department: str, upload_user: str):
    """工厂：返回一个符合签名的 metadata 函数"""
    def rich_meta(fp: Path) -> Dict[str, str]:
        stat = fp.stat()
        return {
            "file_name": fp.name,
            "department": department,   # 外部绑进来的
            "upload_user": upload_user, # 外部绑进来的
            "create_time": datetime.fromtimestamp(stat.st_ctime).isoformat(),
            "confidential": "internal",
        }
    return rich_meta

# 使用
documents = SimpleDirectoryReader(
    "data",
    file_metadata=make_meta_func(department="ABC", upload_user="sam")
).load_data()