在NamedTuple中使用带有可选类型的NamedTuple

Question

有没有可能像这样在NamedTuple中创建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!

Answer 1

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

您还可以让类引用自身：

from __future__ import annotations

from typing import Optional
from dataclasses import dataclass


@dataclass
class Person:

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

Answer 2

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', age=1, body_measurement={'height': [50, 51], 'weight': [3, 3.5]})

实际上，您尝试混合使用两种定义NamedTuple的方法。根据the documentation。

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dataclasses，请参阅foxyblue's answer。