bodies.py

import typing
from dataclasses import dataclass


@dataclass
class BodyBase:
    content_type: str


@dataclass
class JsonBody(BodyBase):
    content_type = "application/json"


@dataclass
class FormBody(BodyBase):
    content_type = "x-www-form-urlencoded"


@dataclass
class MultipartFormDataBody(BodyBase):
    content_type = "multipart/form-data"


def Body(content_type: str) -> typing.Any:
    return BodyBase(content_type=content_type)  # type: ignore


def Json() -> typing.Any:
    return JsonBody()  # type: ignore


def MultipartFormData() -> typing.Any:
    return MultipartFormDataBody()  # type: ignore


def Form() -> typing.Any:
    return FormBody()  # type: ignore


@dataclass
class JsonModel:
    a: int
    b: typing.Dict[str, typing.Any]


@dataclass
class FormModel:
    abc: str
    defg: int


@dataclass
class InnerMultipart:
    json: JsonModel = Json()


@dataclass
class CustomMultipart:
    # when introspection is run, all of these are verified
    # to be instances of BodyBase
    json: JsonModel = Json()
    form: FormModel = Form()
    nested: InnerMultipart = MultipartFormData()


def endpoint(body: CustomMultipart = MultipartFormData()):
    body.json.a
    body.nested.json.a