Fix type overrides for string-annotated dataclasses

HISTORY.md

@@ -13,6 +13,7 @@ Our backwards-compatibility policy can be found [here](https://github.com/python
 
 ## NEXT
 
+- Fix converter type overrides being ignored for dataclass fields with stringified annotations.
 - Dict unstructuring hook factories now inherit the converter's `omit_if_default` setting when `_cattrs_omit_if_default` is omitted. Explicit `True` or `False` values and per-attribute overrides retain their precedence.
   ([#238](https://github.com/python-attrs/cattrs/issues/238))
 - Support the [`frozendict`](https://docs.python.org/3.15/builtins/stdtypes.html#frozendict) built-in on Python 3.15+.

src/cattrs/converters.py

@@ -32,6 +32,7 @@
     Sequence,
     Set,
     TypeAlias,
+    adapted_fields,
     fields,
     frozendict,
     get_final_base,
@@ -44,7 +45,6 @@
     is_counter,
     is_deque,
     is_frozenset,
-    is_generic,
     is_generic_attrs,
     is_hetero_tuple,
     is_literal,
@@ -1321,10 +1321,7 @@ def gen_unstructure_attrs_fromdict(
         self, cl: type[T]
     ) -> Callable[[T], dict[str, Any]]:
         origin = get_origin(cl)
-        attribs = fields(origin or cl)
-        if attrs_has(cl) and any(isinstance(a.type, str) for a in attribs):
-            # PEP 563 annotations - need to be resolved.
-            resolve_types(origin or cl)
+        attribs = adapted_fields(origin or cl)
         attrib_overrides = {
             a.name: self.type_overrides[a.type]
             for a in attribs
@@ -1367,10 +1364,7 @@ def gen_structure_attrs_fromdict(
         self, cl: type[T]
     ) -> Callable[[Mapping[str, Any], Any], T]:
         origin = get_origin(cl)
-        attribs = fields(origin or cl if is_generic(cl) else cl)
-        if attrs_has(cl) and any(isinstance(a.type, str) for a in attribs):
-            # PEP 563 annotations - need to be resolved.
-            resolve_types(origin or cl)
+        attribs = adapted_fields(origin or cl)
         attrib_overrides = {
             a.name: self.type_overrides[a.type]
             for a in attribs

tests/test_converter.py

@@ -1,6 +1,7 @@
 """Test both structuring and unstructuring."""
 
 from collections import deque
+from dataclasses import make_dataclass
 from typing import (
     Annotated,
     Any,
@@ -431,6 +432,31 @@ def test_type_overrides(cl_and_vals):
             assert attr.name not in unstructured
 
 
+@pytest.mark.parametrize("annotation", [int, "int"])
+def test_type_overrides_dataclass_omit_default(annotation):
+    """Type overrides use resolved dataclass field types."""
+    cl = make_dataclass("Settings", [("retries", annotation, 3), ("label", str, "app")])
+    converter = Converter(type_overrides={int: override(omit_if_default=True)})
+
+    assert converter.unstructure(cl()) == {"label": "app"}
+    assert converter.unstructure(cl(5)) == {"retries": 5, "label": "app"}
+
+
+@pytest.mark.parametrize("annotation", [int, "int"])
+@pytest.mark.parametrize("detailed_validation", [True, False])
+def test_type_overrides_dataclass_rename(annotation, detailed_validation):
+    """Renamed dataclass fields work in both directions without prior unstructuring."""
+    cl = make_dataclass("Settings", [("retries", annotation), ("label", str)])
+    converter = Converter(
+        type_overrides={int: override(rename="attempts")},
+        detailed_validation=detailed_validation,
+    )
+
+    inst = converter.structure({"attempts": "5", "label": "app"}, cl)
+    assert inst == cl(5, "app")
+    assert converter.unstructure(inst) == {"attempts": 5, "label": "app"}
+
+
 def test_calling_back():
     """
     Calling unstructure_attrs_asdict from a hook should not override a manual hook.