Source code for cattrs.preconf.json

"""Preconfigured converters for the stdlib json."""
from base64 import b85decode, b85encode
from datetime import date, datetime
from json import dumps, loads
from typing import Any, Type, TypeVar, Union

from cattrs._compat import AbstractSet, Counter

from ..converters import BaseConverter, Converter
from ..strategies import configure_union_passthrough

T = TypeVar("T")


class JsonConverter(Converter):
    def dumps(self, obj: Any, unstructure_as: Any = None, **kwargs: Any) -> str:
        return dumps(self.unstructure(obj, unstructure_as=unstructure_as), **kwargs)

    def loads(self, data: Union[bytes, str], cl: Type[T], **kwargs: Any) -> T:
        return self.structure(loads(data, **kwargs), cl)


def configure_converter(converter: BaseConverter):
    """
    Configure the converter for use with the stdlib json module.

    * bytes are serialized as base64 strings
    * datetimes are serialized as ISO 8601
    * counters are serialized as dicts
    * sets are serialized as lists
    """
    converter.register_unstructure_hook(
        bytes, lambda v: (b85encode(v) if v else b"").decode("utf8")
    )
    converter.register_structure_hook(bytes, lambda v, _: b85decode(v))
    converter.register_unstructure_hook(datetime, lambda v: v.isoformat())
    converter.register_structure_hook(datetime, lambda v, _: datetime.fromisoformat(v))
    converter.register_unstructure_hook(date, lambda v: v.isoformat())
    converter.register_structure_hook(date, lambda v, _: date.fromisoformat(v))
    configure_union_passthrough(Union[str, bool, int, float, None, bytes], converter)


def make_converter(*args: Any, **kwargs: Any) -> JsonConverter:
    kwargs["unstruct_collection_overrides"] = {
        AbstractSet: list,
        Counter: dict,
        **kwargs.get("unstruct_collection_overrides", {}),
    }
    res = JsonConverter(*args, **kwargs)
    configure_converter(res)

    return res