More support for OpenAPI

[techntools]

For generating OpenAPI docs, dataclasses and Pydantic are available.

Dataclasses do not cover as much as Pydantic to specify OpenAPI definitions.

Pydantic offers more, but instead of relying on a third party, can we define field tailored to OpenAPI something like
https://github.com/quantmind/aio-openapi

Or can we use metadata field from builtin dataclasses:

@dataclass
class CreateUser:
    name: str = field(metadata={ 'minLength': 2 })
    email: str
    permissions: List[Permission]

minLength corresponds to actual key used to specify minimum length of field in request body in OpenAPI spec.

Of course this would need knowledge of OpenAPI spec but that would be more beneficial than learning a library.