108 lines
3.5 KiB
Python
108 lines
3.5 KiB
Python
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"""Preconfigured converters for bson."""
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from base64 import b85decode, b85encode
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from datetime import date, datetime
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from typing import Any, Type, TypeVar, Union
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from bson import DEFAULT_CODEC_OPTIONS, CodecOptions, Int64, ObjectId, decode, encode
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from cattrs._compat import AbstractSet, is_mapping
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from cattrs.gen import make_mapping_structure_fn
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from ..converters import BaseConverter, Converter
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from ..strategies import configure_union_passthrough
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from . import validate_datetime
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T = TypeVar("T")
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class Base85Bytes(bytes):
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"""A subclass to help with binary key encoding/decoding."""
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class BsonConverter(Converter):
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def dumps(
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self,
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obj: Any,
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unstructure_as: Any = None,
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check_keys: bool = False,
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codec_options: CodecOptions = DEFAULT_CODEC_OPTIONS,
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) -> bytes:
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return encode(
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self.unstructure(obj, unstructure_as=unstructure_as),
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check_keys=check_keys,
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codec_options=codec_options,
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)
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def loads(
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self,
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data: bytes,
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cl: Type[T],
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codec_options: CodecOptions = DEFAULT_CODEC_OPTIONS,
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) -> T:
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return self.structure(decode(data, codec_options=codec_options), 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 bson library.
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* sets are serialized as lists
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* byte mapping keys are base85-encoded into strings when unstructuring, and reverse
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* non-string, non-byte mapping keys are coerced into strings when unstructuring
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* a deserialization hook is registered for bson.ObjectId by default
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"""
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def gen_unstructure_mapping(cl: Any, unstructure_to=None):
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key_handler = str
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args = getattr(cl, "__args__", None)
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if args:
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if issubclass(args[0], str):
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key_handler = None
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elif issubclass(args[0], bytes):
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def key_handler(k):
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return b85encode(k).decode("utf8")
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return converter.gen_unstructure_mapping(
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cl, unstructure_to=unstructure_to, key_handler=key_handler
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)
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def gen_structure_mapping(cl: Any):
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args = getattr(cl, "__args__", None)
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if args and issubclass(args[0], bytes):
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h = make_mapping_structure_fn(cl, converter, key_type=Base85Bytes)
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else:
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h = make_mapping_structure_fn(cl, converter)
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return h
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converter.register_structure_hook(Base85Bytes, lambda v, _: b85decode(v))
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converter._unstructure_func.register_func_list(
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[(is_mapping, gen_unstructure_mapping, True)]
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)
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converter._structure_func.register_func_list(
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[(is_mapping, gen_structure_mapping, True)]
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)
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converter.register_structure_hook(ObjectId, lambda v, _: ObjectId(v))
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configure_union_passthrough(
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Union[str, bool, int, float, None, bytes, datetime, ObjectId, Int64], converter
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)
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# datetime inherits from date, so identity unstructure hook used
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# here to prevent the date unstructure hook running.
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converter.register_unstructure_hook(datetime, lambda v: v)
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converter.register_structure_hook(datetime, validate_datetime)
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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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def make_converter(*args: Any, **kwargs: Any) -> BsonConverter:
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kwargs["unstruct_collection_overrides"] = {
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AbstractSet: list,
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**kwargs.get("unstruct_collection_overrides", {}),
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}
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res = BsonConverter(*args, **kwargs)
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configure_converter(res)
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return res
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