orjson passthrough (#463)

Author: Tinche

HISTORY.md

@@ -4,6 +4,7 @@
 
 - Add support for [PEP 695](https://peps.python.org/pep-0695/) type aliases.
   ([#452](https://github.com/python-attrs/cattrs/pull/452))
+- The {class}`orjson preconf converter <cattrs.preconf.orjson.OrjsonConverter>` now passes through dates and datetimes to orjson while unstructuring, greatly improving speed.
 - More robust support for `Annotated` and `NotRequired` in TypedDicts.
   ([#450](https://github.com/python-attrs/cattrs/pull/450))
 - [PEP 695](https://peps.python.org/pep-0695/) generics are now tested.

src/cattrs/preconf/orjson.py

@@ -28,7 +28,7 @@ def configure_converter(converter: BaseConverter):
     Configure the converter for use with the orjson library.
 
     * bytes are serialized as base85 strings
-    * datetimes are serialized as ISO 8601
+    * datetimes and dates are passed through to be serialized as RFC 3339 by orjson
     * sets are serialized as lists
     * string enum mapping keys have special handling
     * mapping keys are coerced into strings when unstructuring
@@ -38,9 +38,7 @@ def configure_converter(converter: BaseConverter):
     )
     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))
 
     def gen_unstructure_mapping(cl: Any, unstructure_to=None):