53 lines
1.9 KiB
Python
53 lines
1.9 KiB
Python
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"""Preconfigured converters for the stdlib json."""
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from base64 import b85decode, b85encode
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from datetime import date, datetime
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from json import dumps, loads
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from typing import Any, Type, TypeVar, Union
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from cattrs._compat import AbstractSet, Counter
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from ..converters import BaseConverter, Converter
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from ..strategies import configure_union_passthrough
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T = TypeVar("T")
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class JsonConverter(Converter):
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def dumps(self, obj: Any, unstructure_as: Any = None, **kwargs: Any) -> str:
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return dumps(self.unstructure(obj, unstructure_as=unstructure_as), **kwargs)
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def loads(self, data: Union[bytes, str], cl: Type[T], **kwargs: Any) -> T:
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return self.structure(loads(data, **kwargs), cl)
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def configure_converter(converter: BaseConverter):
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"""
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Configure the converter for use with the stdlib json module.
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* bytes are serialized as base64 strings
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* datetimes are serialized as ISO 8601
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* counters are serialized as dicts
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* sets are serialized as lists
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"""
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converter.register_unstructure_hook(
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bytes, lambda v: (b85encode(v) if v else b"").decode("utf8")
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)
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converter.register_structure_hook(bytes, lambda v, _: b85decode(v))
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converter.register_unstructure_hook(datetime, lambda v: v.isoformat())
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converter.register_structure_hook(datetime, lambda v, _: datetime.fromisoformat(v))
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converter.register_unstructure_hook(date, lambda v: v.isoformat())
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converter.register_structure_hook(date, lambda v, _: date.fromisoformat(v))
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configure_union_passthrough(Union[str, bool, int, float, None, bytes], converter)
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def make_converter(*args: Any, **kwargs: Any) -> JsonConverter:
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kwargs["unstruct_collection_overrides"] = {
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AbstractSet: list,
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Counter: dict,
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**kwargs.get("unstruct_collection_overrides", {}),
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}
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res = JsonConverter(*args, **kwargs)
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configure_converter(res)
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return res
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