Tweak only for dates

Author: Tinche

HISTORY.md

@@ -23,7 +23,9 @@ Our backwards-compatibility policy can be found [here](https://github.com/python
   ([#699](https://github.com/python-attrs/cattrs/issues/699))
 - _cattrs_ now tracks performance using [codspeed](https://codspeed.io/python-attrs/cattrs).
   ([#703](https://github.com/python-attrs/cattrs/pull/703))
-- The {mod}`tomlkit <cattrs.preconf.tomlkit>` preconf converter now properly handles `date` and `datetime` objects when structuring.
+- The {mod}`tomlkit <cattrs.preconf.tomlkit>` preconf converter now properly handles native `date` objects when structuring.
+  ([#707](https://github.com/python-attrs/cattrs/issues/707) [#708](https://github.com/python-attrs/cattrs/pull/708))
+- The {mod}`tomlkit <cattrs.preconf.tomlkit>` preconf converter now passes date objects directly to _tomlkit_ for unstructuring.
   ([#707](https://github.com/python-attrs/cattrs/issues/707) [#708](https://github.com/python-attrs/cattrs/pull/708))
 
 

docs/preconf.md

@@ -55,6 +55,9 @@ Optional install targets should match the name of the {mod}`cattrs.preconf` modu
 # Using pip
 $ pip install cattrs[ujson]
 
+# Usinv uv
+$ uv add cattrs[msgspec]
+
 # Using pdm
 $ pdm add cattrs[orjson]
 
@@ -203,5 +206,5 @@ Found at {mod}`cattrs.preconf.tomlkit`.
 Bytes are serialized as base 85 strings. Sets are serialized as lists, and deserialized back into sets.
 Tuples are serialized as lists, and deserialized back into tuples.
 _tomlkit_ only supports mappings with string keys so mappings will have their keys stringified before serialization, and destringified during deserialization.
-`date` s are serialized as ISO 8601 strings. `datetime` s are passed through to be unstructured by _tomlkit_ itself.
+[`date`](https://docs.python.org/3/library/datetime.html#datetime.date) and [`datetime`](https://docs.python.org/3/library/datetime.html#datetime.datetime) objects are passed through to be unstructured by _tomlkit_ itself.
 

src/cattrs/preconf/tomlkit.py

@@ -12,6 +12,7 @@
 
 from .._compat import is_mapping, is_subclass
 from ..converters import BaseConverter, Converter
+from ..fns import identity
 from ..strategies import configure_union_passthrough
 from . import validate_datetime, wrap
 
@@ -37,6 +38,9 @@ def configure_converter(converter: BaseConverter):
     * sets are serialized as lists
     * tuples are serializas as lists
     * mapping keys are coerced into strings when unstructuring
+
+    .. versionchanged:: NEXT
+        date objects are now passed through to tomlkit without unstructuring.
     """
     converter.register_structure_hook(bytes, lambda v, _: b85decode(v))
     converter.register_unstructure_hook(
@@ -67,11 +71,9 @@ def key_handler(k: bytes):
 
     # datetime inherits from date, so identity unstructure hook used
     # here to prevent the date unstructure hook running.
-    converter.register_unstructure_hook(datetime, lambda v: v)
-    converter.register_structure_hook(
-        datetime, lambda v, _: v if isinstance(v, datetime) else validate_datetime(v, _)
-    )
-    converter.register_unstructure_hook(date, lambda v: v.isoformat())
+    converter.register_unstructure_hook(datetime, identity)
+    converter.register_structure_hook(datetime, validate_datetime)
+    converter.register_unstructure_hook(date, identity)
     converter.register_structure_hook(
         date, lambda v, _: v if isinstance(v, date) else date.fromisoformat(v)
     )

tests/preconf/test_tomlkit.py

@@ -767,6 +767,21 @@ def test_tomlkit_unions(union_and_val: tuple, detailed_validation: bool):
     assert converter.structure(val, type) == val
 
 
+def test_tomlkit_dates():
+    """Native date objects from tomlkit are properly handled."""
+
+    @define
+    class Event:
+        event_date: date
+
+    toml_input = """
+event_date = 2025-12-16
+"""
+    converter = tomlkit_make_converter()
+    structured = converter.loads(toml_input, Event)
+    assert structured.event_date == date(2025, 12, 16)
+
+
 @given(everythings(min_int=-9223372036854775808, max_int=18446744073709551615))
 def test_cbor2(everything: Everything):
     from cbor2 import dumps as cbor2_dumps