在 NamedTuple 中使用 NamedTuple 和可选类型

问题描述

是否可以像这样在 NamedTuple 内部创建 NamedTuple？

from typing import NamedTuple,List,Optional
class BabyData(NamedTuple):
    name: str
    age: int
    body_measurement: Optional[NamedTuple('height': List,'weight': List)] = None

谢谢！

解决方法

您可能希望在此用例中使用 dataclasses：

from typing import Optional
from dataclasses import dataclass


@dataclass
class Measurements:

    height: list
    weight: list


@dataclass
class Baby:

    name: str
    age: int
    body: Optional[Measurements] = None

你也可以让类引用自己：

from __future__ import annotations

from typing import Optional
from dataclasses import dataclass


@dataclass
class Person:

    name: str
    age: int
    parent: Optional[Person] = None

,

提供的示例在运行时输出错误。

body_measurement: Optional[NamedTuple('height': List,'weight': List)] = None
                                                  ^
SyntaxError: invalid syntax

要修复它，您需要

from typing import NamedTuple,List,Optional

class BabyData(NamedTuple):
    name: str
    age: int
    body_measurement: Optional[
        NamedTuple("BodyMeasurement",[("height",List),("weight",List)])
    ] = None

if __name__ == "__main__":
    baby = BabyData(
        name="john",age=1,body_measurement={"height": [50,51],"weight": [3,3.5]}
    )
    print(baby)

# BabyData(name='john',body_measurement={'height': [50,'weight': [3,3.5]})

实际上，您尝试混合定义 NamedTuple 的两种方式。根据{{​​3}}。

class Employee(NamedTuple):
    name: str
    id: int
# This is equivalent to:

Employee = collections.namedtuple('Employee',['name','id'])

您还应该考虑使用 the documentation，请参阅 dataclasses。