How to hint lists of fields

[Wyko]

I'd like to reuse a field definition, and sometimes a field gets used in a list. See below:

ConfigField: dict = Field(
    default_factory=dict,
    title="The configuration.",
    description="A dictionary containing the configuration.",
)

class Config(BaseModel):
    config: dict = ConfigField

class MultiConfig(BaseModel, arbitrary_types_allowed=True):
    configs: list[ConfigField]

Unfortunately this does not work. The line configs: list[TenantConfigField] errors out.

What is the correct way to do this?

[uriyyo]

Hi @Wyko,

If you are using pydantic v2 you can use Annotated to add Field to specific type:

from typing import Annotated, TypeAlias

from pydantic import Field, BaseModel

ConfigField: TypeAlias = Annotated[
    dict,
    Field(
        default_factory=dict,
        title="The configuration.",
        description="A dictionary containing the configuration.",
    )
]


class Config(BaseModel):
    config: ConfigField


class MultiConfig(BaseModel):
    configs: list[ConfigField]


multi_config = MultiConfig(
    configs=[
        {"key": "value"},
        {"key": "value"},
    ]
)

print(multi_config)