✳️ 🧙 🖐🏻 マシュマロライブラリを使用したPythonでの厳密なYAMLデシリアライズ 👐🏻 🚱 💿

初期タスク

.yamlファイルから重要な設定を読み取る必要があります。
構成構造は、データクラスを使用して記述されます。
デシリアライズ中に型チェックを実行する必要があり、データが無効な場合は例外がスローされます。

つまり、簡単に言うと、次の形式の関数が必要です。

def strict_load_yaml(yaml: str, loaded_type: Type[Any]):
    """
    Here is some magic
    """
    pass

そして、この関数は次のように使用されます。

@dataclass
class MyConfig:
    """
    Here is object tree
    """
    pass

try:
    config = strict_load_yamp(open("config.yaml", "w").read(), MyConfig)
except Exception:
    logging.exception("Config is invalid")

構成クラス

ファイルconfig.py

は次のようになります。

from dataclasses import dataclass
from enum import Enum
from typing import Optional

class Color(Enum):
    RED = "red"
    GREEN = "green"
    BLUE = "blue"

@dataclass
class BattleStationConfig:
    @dataclass
    class Processor:
        core_count: int
        manufacturer: str

    processor: Processor
    memory_gb: int
    led_color: Optional[Color] = None

動作しないオプション

, ? . yaml- ?

PyYaml load

:

from pprint import pprint

from yaml import load, SafeLoader

yaml = """
processor:
  core_count: 8
  manufacturer: Intel
memory_gb: 8
led_color: red
"""

loaded = load(yaml, Loader=SafeLoader)
pprint(loaded)

{'led_color': 'red',
 'memory_gb': 8,
 'processor': {'core_count': 8, 'manufacturer': 'Intel'}}

Yaml , . , **args

:

parsed_config = BattleStationConfig(**loaded)
pprint(parsed_config)

BattleStationConfig(processor={'core_count': 8, 'manufacturer': 'Intel'}, memory_gb=8, led_color='red')

! ! … -. processor ? .

Python Processor

. stackowerflow.

, yaml-

stackowerflow PyYaml , yaml- . YAMLObject

, config_with_tag.py

:

from dataclasses import dataclass
from enum import Enum
from typing import Optional

from yaml import YAMLObject, SafeLoader

class Color(Enum):
    RED = "red"
    GREEN = "green"
    BLUE = "blue"

@dataclass
class BattleStationConfig(YAMLObject):
    yaml_tag = "!BattleStationConfig"
    yaml_loader = SafeLoader

    @dataclass
    class Processor(YAMLObject):
        yaml_tag = "!Processor"
        yaml_loader = SafeLoader

        core_count: int
        manufacturer: str

    processor: Processor
    memory_gb: int
    led_color: Optional[Color] = None

from pprint import pprint

from yaml import load, SafeLoader

from config_with_tag import BattleStationConfig

yaml = """
--- !BattleStationConfig
processor: !Processor
  core_count: 8
  manufacturer: Intel
memory_gb: 8
led_color: red
"""

a = BattleStationConfig

loaded = load(yaml, Loader=SafeLoader)
pprint(loaded)

BattleStationConfig(processor=BattleStationConfig.Processor(core_count=8, manufacturer='Intel'), memory_gb=8, led_color='red')

. yaml- . , Color

- . YAMLObject

? ? , .

class Color(Enum, YAMLObject):
    RED = "red"
    GREEN = "green"
    BLUE = "blue"

TypeError: metaclass conflict: the metaclass of a derived class must be a (non-strict) subclass of the metaclasses of all its bases

. yaml-, .

marshmallow

stackowerflow marshmallow , JSON-. , , , yaml JSON. class_schema

, -:

from pprint import pprint

from yaml import load, SafeLoader
from marshmallow_dataclass import class_schema

from config import BattleStationConfig

yaml = """
processor:
  core_count: 8
  manufacturer: Intel
memory_gb: 8
led_color: red
"""

loaded = load(yaml, Loader=SafeLoader)
pprint(loaded)

BattleStationConfigSchema = class_schema(BattleStationConfig)

result = BattleStationConfigSchema().load(loaded)
pprint(result)

, , :

marshmallow.exceptions.ValidationError: {'led_color': ['Invalid enum member red']}

, marshmallow enum, . yaml- :

processor:
  core_count: 8
  manufacturer: Intel
memory_gb: 8
led_color: RED

, , :

BattleStationConfig(processor=BattleStationConfig.Processor(core_count=8, manufacturer='Intel'), memory_gb=8, led_color=<Color.RED: 'red'>)

, yaml-. marshmallow :

Setting by_value=True

. This will cause both dumping and loading to use the value of the enum.

, metadata

field

:

@dataclass
class BattleStationConfig:
    led_color: Optional[Color] = field(default=None, metadata={"by_value": True})

, "" , yaml-.

, :

def strict_load_yaml(yaml: str, loaded_type: Type[Any]):
    schema = class_schema(loaded_type)
    return schema().load(load(yaml, Loader=SafeLoader))

-, yaml.

ForwardRef

- ForwardRef ( ) marshmallow .

from dataclasses import dataclass, field
from enum import Enum
from typing import Optional, ForwardRef

@dataclass
class BattleStationConfig:
    processor: ForwardRef("Processor")
    memory_gb: int
    led_color: Optional["Color"] = field(default=None, metadata={"by_value": True})

    @dataclass
    class Processor:
        core_count: int
        manufacturer: str

class Color(Enum):
    RED = "red"
    GREEN = "green"
    BLUE = "blue"

marshmallow.exceptions.RegistryError: Class with name 'Processor' was not found. You may need to import the class.

また、クラスを上に移動するとProcessor

、マシュマロはColor

同様のエラーでクラスを失います。したがって、可能であれば、マシュマロでクラスを解析する場合は、クラスでForwardRefを使用しないでください。

コード

すべてのコードはGitHubリポジトリで入手できます。

マシュマロライブラリを使用したPythonでの厳密なYAMLデシリアライズ