ruamel.yaml无法处理NamedTuple

Question

所以我有下面的代码：

import sys
from typing import NamedTuple

import ruamel.yaml as ryaml


class Loc(NamedTuple):
    lat: float
    long: float


data = {
    "APAC": {
        "rating": 5,
        "leads": ["Jane", "John"],
        "locs": [Loc(1.0, 1.0), Loc(2.0, 2.0)],
    },
    "EMEA": {
        "rating": 5,
        "leads": ["Jane", "Jack"],
        "locs": [Loc(3.0, 3.0), Loc(4.0, 4.0)],
    }
}


def main():
    # Just to check that Loc is indeed recognized as a tuple
    assert all(map(lambda o: isinstance(o, tuple), data["APAC"]["locs"]))
    assert all(map(lambda o: isinstance(o, tuple), data["EMEA"]["locs"]))

    yml = ryaml.YAML()
    yml.register_class(Loc)
    yml.dump(data, sys.stdout)


if __name__ == '__main__':
    main()

但是，每当我执行代码时，我都会得到一系列的异常，结尾是：

  File "C:\Repos\@Venv\myproj-cpy3.11-1\Lib\site-packages\ruamel\yaml\representer.py", line 1090, in represent_yaml_object
    anchor = state.pop(Anchor.attrib, None)
             ^^^^^^^^^
AttributeError: 'NoneType' object has no attribute 'pop'

如果我使用'bare‘tuple而不是Loc()，错误就不会出现。

我如何使ruamel.yaml理解Loc是一个NamedTuple是一个tuple

我用的是CPython 3.11和ruamel.yaml==0.17.21

Answer 1

由于某种原因，您注册了Loc类，但您没有告诉ruamel.yaml如何转储该类，并且该信息不会自动添加，而且相对较新的特性(如NamedTuple和DataClasses(没有被ruamel.yaml代码基以特殊方式显式识别和处理)(如果是的话，它们甚至可能不需要注册倾销，但它们可能需要加载)。

文档中的示例显示，这是为已注册的类完成的，即通过添加一个to_yaml类方法，所以您也需要对Loc这样做。

import sys
from typing import NamedTuple
import ruamel.yaml

class Loc(NamedTuple):
    lat: float
    long: float

    @classmethod
    def to_yaml(cls, representer, node):
        return representer.represent_sequence('!Loc', node)
 
data = {
    "APAC": {
        "rating": 5,
        "leads": ["Jane", "John"],
        "locs": [Loc(1.0, 1.0), Loc(2.0, 2.0)],
    },
    "EMEA": {
        "rating": 5,
        "leads": ["Jane", "Jack"],
        "locs": [Loc(3.0, 3.0), Loc(4.0, 4.0)],
    }
}

def main():
    assert all(map(lambda o: isinstance(o, tuple), data["APAC"]["locs"]))
    assert all(map(lambda o: isinstance(o, tuple), data["EMEA"]["locs"]))

    yaml = ruamel.yaml.YAML()
    yaml.register_class(Loc)
    yaml.dump(data, sys.stdout)

main()

这意味着：

APAC:
  rating: 5
  leads:
  - Jane
  - John
  locs:
  - !Loc
    - 1.0
    - 1.0
  - !Loc
    - 2.0
    - 2.0
EMEA:
  rating: 5
  leads:
  - Jane
  - Jack
  locs:
  - !Loc
    - 3.0
    - 3.0
  - !Loc
    - 4.0
    - 4.0