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https://github.com/long2ice/fastapi-cache.git
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23d439f83a
This is, for the majority of backends, the native format anyway, and so we save encoding and decoding when using the PickleCodec or if (in future) a orjson Coder was to be added. For the JsonCodec, the only thing that changed is the location where the JSON data is encoded to bytes and decoded back again to a string.
127 lines
4.0 KiB
Python
127 lines
4.0 KiB
Python
import datetime
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import json
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import pickle # nosec:B403
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from decimal import Decimal
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from typing import Any, Callable, ClassVar, Dict, Optional, TypeVar, Union, overload
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import pendulum
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from fastapi.encoders import jsonable_encoder
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from pydantic import BaseConfig, ValidationError, fields
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from starlette.responses import JSONResponse
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from starlette.templating import _TemplateResponse as TemplateResponse
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_T = TypeVar("_T")
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CONVERTERS: dict[str, Callable[[str], Any]] = {
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"date": lambda x: pendulum.parse(x, exact=True),
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"datetime": lambda x: pendulum.parse(x, exact=True),
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"decimal": Decimal,
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}
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class JsonEncoder(json.JSONEncoder):
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def default(self, obj: Any) -> Any:
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if isinstance(obj, datetime.datetime):
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return {"val": str(obj), "_spec_type": "datetime"}
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elif isinstance(obj, datetime.date):
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return {"val": str(obj), "_spec_type": "date"}
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elif isinstance(obj, Decimal):
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return {"val": str(obj), "_spec_type": "decimal"}
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else:
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return jsonable_encoder(obj)
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def object_hook(obj: Any) -> Any:
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_spec_type = obj.get("_spec_type")
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if not _spec_type:
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return obj
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if _spec_type in CONVERTERS:
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return CONVERTERS[_spec_type](obj["val"])
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else:
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raise TypeError("Unknown {}".format(_spec_type))
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class Coder:
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@classmethod
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def encode(cls, value: Any) -> bytes:
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raise NotImplementedError
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@classmethod
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def decode(cls, value: bytes) -> Any:
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raise NotImplementedError
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# (Shared) cache for endpoint return types to Pydantic model fields.
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# Note that subclasses share this cache! If a subclass overrides the
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# decode_as_type method and then stores a different kind of field for a
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# given type, do make sure that the subclass provides its own class
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# attribute for this cache.
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_type_field_cache: ClassVar[Dict[Any, fields.ModelField]] = {}
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@overload
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@classmethod
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def decode_as_type(cls, value: bytes, *, type_: _T) -> _T:
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...
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@overload
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@classmethod
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def decode_as_type(cls, value: bytes, *, type_: None) -> Any:
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...
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@classmethod
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def decode_as_type(cls, value: bytes, *, type_: Optional[_T]) -> Union[_T, Any]:
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"""Decode value to the specific given type
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The default implementation uses the Pydantic model system to convert the value.
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"""
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result = cls.decode(value)
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if type_ is not None:
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try:
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field = cls._type_field_cache[type_]
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except KeyError:
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field = cls._type_field_cache[type_] = fields.ModelField(
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name="body", type_=type_, class_validators=None, model_config=BaseConfig
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)
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result, errors = field.validate(result, {}, loc=())
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if errors is not None:
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if not isinstance(errors, list):
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errors = [errors]
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raise ValidationError(errors, type_)
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return result
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class JsonCoder(Coder):
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@classmethod
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def encode(cls, value: Any) -> bytes:
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if isinstance(value, JSONResponse):
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return value.body
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return json.dumps(value, cls=JsonEncoder).encode()
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@classmethod
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def decode(cls, value: bytes) -> Any:
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# explicitly decode from UTF-8 bytes first, as otherwise
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# json.loads() will first have to detect the correct UTF-
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# encoding used.
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return json.loads(value.decode(), object_hook=object_hook)
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class PickleCoder(Coder):
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@classmethod
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def encode(cls, value: Any) -> bytes:
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if isinstance(value, TemplateResponse):
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value = value.body
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return pickle.dumps(value)
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@classmethod
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def decode(cls, value: bytes) -> Any:
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return pickle.loads(value) # nosec:B403,B301
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@classmethod
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def decode_as_type(cls, value: bytes, *, type_: Optional[_T]) -> Any:
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# Pickle already produces the correct type on decoding, no point
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# in paying an extra performance penalty for pydantic to discover
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# the same.
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return cls.decode(value)
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