访问Python dict中的项

假设我有一个过滤数据的函数,如下所示:

from typing import Dict, Union


def filterData(data: Dict[str, str], fields: Union[list, tuple]) -> dict:

    filteredData = {}

    for field in fields:
        if field in data:
            filteredData[field] = data[field]

    return filteredData

我这样使用这个函数:

data = filterData({"a": "b", "c": "d"}, ("a")) # This should return {"a": "b"}.

现在,当我试图接近 a 性质类似 data.a ,我得到一个错误,上面写着 Instance of dict has no member a . 如何定义和应用定义该词典所有成员的类型?

我试着创建一个类,

class ReqData():
    a: str

然后像这样应用到变量上,

data: ReqData = filterData({"a": "b", "c": "d"}, ("a")