fastapi/fastapi/encoders.py

from enum import Enum
from types import GeneratorType
from typing import Any, Set

from pydantic import BaseModel
from pydantic.json import ENCODERS_BY_TYPE


def jsonable_encoder(
    obj: Any,
    include: Set[str] = None,
    exclude: Set[str] = set(),
    by_alias: bool = False,
    include_none: bool = True,
    custom_encoder: dict = {},
) -> Any:
    if isinstance(obj, BaseModel):
        encoder = getattr(obj.Config, "json_encoders", custom_encoder)
        return jsonable_encoder(
            obj.dict(include=include, exclude=exclude, by_alias=by_alias),
            include_none=include_none,
            custom_encoder=encoder,
        )
    if isinstance(obj, Enum):
        return obj.value
    if isinstance(obj, (str, int, float, type(None))):
        return obj
    if isinstance(obj, dict):
        return {
            jsonable_encoder(
                key,
                by_alias=by_alias,
                include_none=include_none,
                custom_encoder=custom_encoder,
            ): jsonable_encoder(
                value,
                by_alias=by_alias,
                include_none=include_none,
                custom_encoder=custom_encoder,
            )
            for key, value in obj.items()
            if value is not None or include_none
        }
    if isinstance(obj, (list, set, frozenset, GeneratorType, tuple)):
        return [
            jsonable_encoder(
                item,
                include=include,
                exclude=exclude,
                by_alias=by_alias,
                include_none=include_none,
                custom_encoder=custom_encoder,
            )
            for item in obj
        ]
    errors = []
    try:
        if custom_encoder and type(obj) in custom_encoder:
            encoder = custom_encoder[type(obj)]
        else:
            encoder = ENCODERS_BY_TYPE[type(obj)]
        return encoder(obj)
    except KeyError as e:
        errors.append(e)
        try:
            data = dict(obj)
        except Exception as e:
            errors.append(e)
            try:
                data = vars(obj)
            except Exception as e:
                errors.append(e)
                raise ValueError(errors)
    return jsonable_encoder(data, by_alias=by_alias, include_none=include_none)