Nested attrs.define dataclasses not serialized correctly when a subfield is also an attrs.define dataclass marked with attrs.field

CHANGELOG.rst

@@ -19,6 +19,9 @@ Fixed
 ^^^^^
 - Help for ``Protocol`` types not working correctly (`#645
   <https://github.com/omni-us/jsonargparse/pull/645>`__).
+- Adding ``attrs.define`` dataclasses with nested dataclasses that are marked with
+  ``attrs.field`` (such as for a default factory) are not parsed correctly (`#643
+  <https://github.com/omni-us/jsonargparse/pull/643>`__)
 
 
 v4.35.0 (2024-12-16)
@@ -52,7 +55,6 @@ Deprecated
   config argument as ``--print_%s`` instead of being always ``--print_config``
   (`#630 <https://github.com/omni-us/jsonargparse/pull/630>`__).
 
-
 v4.34.1 (2024-12-02)
 --------------------
 

jsonargparse/_signatures.py

@@ -17,12 +17,8 @@
     is_subclass,
 )
 from ._namespace import Namespace
-from ._optionals import get_doc_short_description, is_pydantic_model, pydantic_support
-from ._parameter_resolvers import (
-    ParamData,
-    get_parameter_origins,
-    get_signature_parameters,
-)
+from ._optionals import attrs_support, get_doc_short_description, is_pydantic_model, pydantic_support
+from ._parameter_resolvers import ParamData, get_parameter_origins, get_signature_parameters
 from ._typehints import (
     ActionTypeHint,
     LazyInitBaseClass,
@@ -575,6 +571,13 @@ def dataclass_to_dict(value) -> dict:
         pydantic_model = is_pydantic_model(type(value))
         if pydantic_model:
             return value.dict() if pydantic_model == 1 else value.model_dump()
+
+    if attrs_support:
+        import attrs
+
+        is_attrs_dataclass = attrs.has(type(value))
+        if is_attrs_dataclass:
+            return attrs.asdict(value)
     return dataclasses.asdict(value)
 
 

jsonargparse_tests/test_dataclass_like.py

@@ -8,13 +8,7 @@
 import pytest
 import yaml
 
-from jsonargparse import (
-    ArgumentError,
-    ArgumentParser,
-    Namespace,
-    compose_dataclasses,
-    lazy_instance,
-)
+from jsonargparse import ArgumentError, ArgumentParser, Namespace, compose_dataclasses, lazy_instance
 from jsonargparse._namespace import NSKeyError
 from jsonargparse._optionals import (
     attrs_support,
@@ -25,10 +19,7 @@
     typing_extensions_import,
 )
 from jsonargparse.typing import PositiveFloat, PositiveInt, final
-from jsonargparse_tests.conftest import (
-    get_parser_help,
-    skip_if_docstring_parser_unavailable,
-)
+from jsonargparse_tests.conftest import get_parser_help, skip_if_docstring_parser_unavailable
 
 annotated = typing_extensions_import("Annotated")
 type_alias_type = typing_extensions_import("TypeAliasType")
@@ -942,6 +933,21 @@ class AttrsFieldInitFalse:
         def __attrs_post_init__(self):
             self.p1 = {}
 
+    @attrs.define
+    class AttrsSubField:
+        p1: str = "-"
+        p2: int = 0
+
+    @attrs.define
+    class AttrsWithNestedDefaultDataclass:
+        p1: float
+        subfield: AttrsSubField = attrs.field(factory=AttrsSubField)
+
+    @attrs.define
+    class AttrsWithNestedDataclassNoDefault:
+        p1: float
+        subfield: AttrsSubField
+
 
 @pytest.mark.skipif(not attrs_support, reason="attrs package is required")
 class TestAttrs:
@@ -978,3 +984,13 @@ def test_field_init_false(self, parser):
         assert cfg == Namespace()
         init = parser.instantiate_classes(cfg)
         assert init.data.p1 == {}
+
+    def test_nested_with_default(self, parser):
+        parser.add_argument("--data", type=AttrsWithNestedDefaultDataclass)
+        cfg = parser.parse_args(["--data.p1=1.23"])
+        assert cfg.data == Namespace(p1=1.23, subfield=Namespace(p1="-", p2=0))
+
+    def test_nested_without_default(self, parser):
+        parser.add_argument("--data", type=AttrsWithNestedDataclassNoDefault)
+        cfg = parser.parse_args(["--data.p1=1.23"])
+        assert cfg.data == Namespace(p1=1.23, subfield=Namespace(p1="-", p2=0))