pydantic-settings 支持 json, yaml, toml 配置

pydantic-settings 支持从 json, yaml, toml 文件中读取配置。

1 - 使用方法

关键是重写 settings_customise_sources 方法，并返回一个包含所有配置源的元组。

from pydantic_settings import (
    BaseSettings,
    PydanticBaseSettingsSource,
    SettingsConfigDict,
    TomlConfigSettingsSource,
)

TOML_FILES = ["config.toml"]  # 配置文件路径

class Settings(BaseSettings):
    model_config = SettingsConfigDict(toml_file=TOML_FILES)

    @classmethod
    def settings_customise_sources(
        cls,
        settings_cls: type[BaseSettings],
        init_settings: PydanticBaseSettingsSource,
        env_settings: PydanticBaseSettingsSource,
        dotenv_settings: PydanticBaseSettingsSource,
        file_secret_settings: PydanticBaseSettingsSource,
    ) -> tuple[PydanticBaseSettingsSource, ...]:
        # the first source has the highest priority
        return (
            env_settings,
            dotenv_settings,
            file_secret_settings,
            TomlConfigSettingsSource(settings_cls),
            init_settings,
        )

Pydantic 提供如下的配置源:

• JsonConfigSettingsSource 使用 json_file 和 json_file_encoding 参数
• PyprojectTomlConfigSettingsSource 使用 (optional) pyproject_toml_depth 和 (optional) pyproject_toml_table_header 参数
• TomlConfigSettingsSource 使用 toml_file 参数
• YamlConfigSettingsSource 使用 yaml_file 和 yaml_file_encoding 参数

也可以继承 PydanticBaseSettingsSource 类，编写自定义的配置源

https://docs.pydantic.dev/2.11/concepts/pydantic_settings/?query=toml#adding-sources

2 - 问题

2.1 如何动态选择配置文件?

TomlConfigSettingsSource 等 settings source 类支持传入配置文件列表，支持多个配置文件。

根据 Issue #259, 暂时不能很优雅地动态改变配置文件列表。

不过还是可以用全局变量、环境变量等方式实现。

Example 1: 使用全局变量

TOML_FILES = ["config.toml", "config.local.toml"]

class Settings(BaseSettings):
    @classmethod
    def settings_customise_sources(
        cls,
        settings_cls: type[BaseSettings],
        init_settings: PydanticBaseSettingsSource,
        env_settings: PydanticBaseSettingsSource,
        dotenv_settings: PydanticBaseSettingsSource,
        file_secret_settings: PydanticBaseSettingsSource,
    ) -> tuple[PydanticBaseSettingsSource, ...]:
        # the first source has the highest priority
        return (
            env_settings,
            dotenv_settings,
            file_secret_settings,
            TomlConfigSettingsSource(settings_cls, TOML_FILES),
            init_settings,
        )

Example 2: 使用环境变量

class Settings(BaseSettings):
    @classmethod
    def settings_customise_sources(
        cls,
        settings_cls: type[BaseSettings],
        init_settings: PydanticBaseSettingsSource,
        env_settings: PydanticBaseSettingsSource,
        dotenv_settings: PydanticBaseSettingsSource,
        file_secret_settings: PydanticBaseSettingsSource,
    ) -> tuple[PydanticBaseSettingsSource, ...]:
        # the first source has the highest priority
        toml_files = os.environ.get("toml_config_files", "config.toml")
        return (
            env_settings,
            dotenv_settings,
            file_secret_settings,
            TomlConfigSettingsSource(settings_cls, toml_files),
            init_settings,
        )