feat: add support to msgspec for kw_only=True (#2162)

Co-authored-by: Koudai Aono <[email protected]>

datamodel_code_generator/__main__.py

@@ -186,8 +186,13 @@ def validate_custom_file_header(cls, values: Dict[str, Any]) -> Dict[str, Any]:
 
     @model_validator(mode='after')
     def validate_keyword_only(cls, values: Dict[str, Any]) -> Dict[str, Any]:
+        output_model_type: DataModelType = values.get('output_model_type')
         python_target: PythonVersion = values.get('target_python_version')
-        if values.get('keyword_only') and not python_target.has_kw_only_dataclass:
+        if (
+            values.get('keyword_only')
+            and output_model_type == DataModelType.DataclassesDataclass
+            and not python_target.has_kw_only_dataclass
+        ):
             raise Error(
                 f'`--keyword-only` requires `--target-python-version` {PythonVersion.PY_310.value} or higher.'
             )

datamodel_code_generator/model/msgspec.py

@@ -31,7 +31,6 @@
     IMPORT_MSGSPEC_CONVERT,
     IMPORT_MSGSPEC_FIELD,
     IMPORT_MSGSPEC_META,
-    IMPORT_MSGSPEC_STRUCT,
 )
 from datamodel_code_generator.model.pydantic.base_model import (
     Constraints as _Constraints,
@@ -88,7 +87,7 @@ class RootModel(_RootModel):
 class Struct(DataModel):
     TEMPLATE_FILE_PATH: ClassVar[str] = 'msgspec.jinja2'
     BASE_CLASS: ClassVar[str] = 'msgspec.Struct'
-    DEFAULT_IMPORTS: ClassVar[Tuple[Import, ...]] = (IMPORT_MSGSPEC_STRUCT,)
+    DEFAULT_IMPORTS: ClassVar[Tuple[Import, ...]] = ()
 
     def __init__(
         self,
@@ -123,6 +122,8 @@ def __init__(
             keyword_only=keyword_only,
         )
         self.extra_template_data.setdefault('base_class_kwargs', {})
+        if self.keyword_only:
+            self.add_base_class_kwarg('kw_only', 'True')
 
     def add_base_class_kwarg(self, name: str, value):
         self.extra_template_data['base_class_kwargs'][name] = value

tests/data/expected/main/jsonschema/require_referenced_field_msgspec/referenced.py

@@ -0,0 +1,14 @@
+# generated by datamodel-codegen:
+#   filename:  referenced.json
+#   timestamp: 2019-07-26T00:00:00+00:00
+
+from __future__ import annotations
+
+from typing import Optional
+
+from msgspec import Struct
+
+
+class Model(Struct):
+    some_optional_property: Optional[str] = None
+    some_optional_typed_property: Optional[str] = None

tests/data/expected/main/jsonschema/require_referenced_field_msgspec/required.py

@@ -0,0 +1,12 @@
+# generated by datamodel-codegen:
+#   filename:  required.json
+#   timestamp: 2019-07-26T00:00:00+00:00
+
+from __future__ import annotations
+
+from .referenced import Model as Model_1
+
+
+class Model(Model_1):
+    some_optional_property: str
+    some_optional_typed_property: str

tests/data/expected/main/openapi/msgspec_keyword_only.py

@@ -0,0 +1,20 @@
+# generated by datamodel-codegen:
+#   filename:  inheritance.yaml
+#   timestamp: 2019-07-26T00:00:00+00:00
+
+from __future__ import annotations
+
+from typing import Optional
+
+from msgspec import Struct
+
+
+class Base(Struct, kw_only=True):
+    id: str
+    createdAt: Optional[str] = None
+    version: Optional[float] = 1
+
+
+class Child(Base, kw_only=True):
+    title: str
+    url: Optional[str] = 'https://example.com'

tests/main/jsonschema/test_main_jsonschema.py

@@ -1096,6 +1096,10 @@ def test_main_require_referenced_field_naivedatetime(output_model, expected_outp
             'pydantic_v2.BaseModel',
             'require_referenced_field',
         ),
+        (
+            'msgspec.Struct',
+            'require_referenced_field_msgspec',
+        ),
     ],
 )
 @freeze_time('2019-07-26')

tests/main/openapi/test_main_openapi.py

@@ -2993,3 +2993,33 @@ def test_main_openapi_dataclass_with_NaiveDatetime(capsys: CaptureFixture):
         captured.err
         == '`--output-datetime-class` only allows "datetime" for `--output-model-type` dataclasses.dataclass\n'
     )
+
+
+@freeze_time('2019-07-26')
+@pytest.mark.skipif(
+    black.__version__.split('.')[0] == '19',
+    reason="Installed black doesn't support the old style",
+)
+def test_main_openapi_keyword_only_msgspec():
+    with TemporaryDirectory() as output_dir:
+        output_file: Path = Path(output_dir) / 'output.py'
+        return_code: Exit = main(
+            [
+                '--input',
+                str(OPEN_API_DATA_PATH / 'inheritance.yaml'),
+                '--output',
+                str(output_file),
+                '--input-file-type',
+                'openapi',
+                '--output-model-type',
+                'msgspec.Struct',
+                '--keyword-only',
+                '--target-python-version',
+                '3.8',
+            ]
+        )
+        assert return_code == Exit.OK
+        assert (
+            output_file.read_text()
+            == (EXPECTED_OPENAPI_PATH / 'msgspec_keyword_only.py').read_text()
+        )