feat: switch default output model to pydantic v2 (#3029)

Author: koxudaxi

src/datamodel_code_generator/__main__.py

@@ -420,7 +420,7 @@ def validate_class_name_affix_scope(cls, v: str | ClassNameAffixScope | None) ->
     input_model: Optional[list[str]] = None  # noqa: UP045
     input_model_ref_strategy: Optional[InputModelRefStrategy] = None  # noqa: UP045
     input_file_type: InputFileType = InputFileType.Auto
-    output_model_type: DataModelType = DataModelType.PydanticBaseModel
+    output_model_type: DataModelType = DataModelType.PydanticV2BaseModel
     output: Optional[Path] = None  # noqa: UP045
     check: bool = False
     debug: bool = False
@@ -1127,22 +1127,6 @@ def main(args: Sequence[str] | None = None) -> Exit:  # noqa: PLR0911, PLR0912,
     if config.disable_warnings:
         warnings.simplefilter("ignore")
 
-    if (
-        namespace.output_model_type is None
-        and pyproject_config.get("output_model_type") is None
-        and config.output_model_type == DataModelType.PydanticBaseModel
-    ):
-        warnings.warn(
-            "No --output-model-type specified. "
-            "The current default (pydantic.BaseModel, Pydantic v1) is deprecated "
-            "and will be removed in a future version. "
-            "Please explicitly specify --output-model-type. "
-            "Example: --output-model-type pydantic_v2.BaseModel. "
-            "See https://github.com/koxudaxi/datamodel-code-generator/issues/2466",
-            DeprecationWarning,
-            stacklevel=1,
-        )
-
     if (
         config.output_model_type in {DataModelType.PydanticV2BaseModel, DataModelType.PydanticV2Dataclass}
         and not config.use_annotated

src/datamodel_code_generator/arguments.py

@@ -177,7 +177,7 @@ def start_section(self, heading: str | None) -> None:
 )
 base_options.add_argument(
     "--output-model-type",
-    help="Output model type (default: pydantic.BaseModel)",
+    help="Output model type (default: pydantic_v2.BaseModel)",
     choices=[i.value for i in DataModelType],
 )
 base_options.add_argument(

src/datamodel_code_generator/config.py

@@ -68,7 +68,7 @@ class GenerateConfig(BaseModel):
     input_filename: str | None = None
     input_file_type: InputFileType = InputFileType.Auto
     output: Path | None = None
-    output_model_type: DataModelType = DataModelType.PydanticBaseModel
+    output_model_type: DataModelType = DataModelType.PydanticV2BaseModel
     target_python_version: PythonVersion = PythonVersionMin
     target_pydantic_version: TargetPydanticVersion | None = None
     base_class: str = ""

src/datamodel_code_generator/input_model.py

@@ -705,7 +705,7 @@ def load_model_schema(  # noqa: PLR0912, PLR0914, PLR0915
     from datamodel_code_generator.arguments import InputModelRefStrategy  # noqa: PLC0415
 
     if output_model_type is None:
-        output_model_type = DataModelType.PydanticBaseModel
+        output_model_type = DataModelType.PydanticV2BaseModel
 
     if len(input_models) == 1:
         return _load_single_model_schema(input_models[0], input_file_type, ref_strategy, output_model_type)

tests/data/expected/main/space_and_special_characters_dict_default_v2.py

@@ -0,0 +1,46 @@
+# generated by datamodel-codegen:
+#   filename:  space_and_special_characters_dict.py
+#   timestamp: 2019-07-26T00:00:00+00:00
+
+from __future__ import annotations
+
+from pydantic import BaseModel, Field
+
+
+class InitialParameters(BaseModel):
+    V1: int
+    V2: int
+
+
+class Data(BaseModel):
+    Length__m_: float = Field(..., alias='Length (m)')
+    Symmetric_deviation____: float = Field(..., alias='Symmetric deviation (%)')
+    Total_running_time__s_: int = Field(..., alias='Total running time (s)')
+    Mass__kg_: float = Field(..., alias='Mass (kg)')
+    Initial_parameters: InitialParameters = Field(..., alias='Initial parameters')
+    class_: str = Field(..., alias='class')
+
+
+class Values(BaseModel):
+    field_1_Step: str = Field(..., alias='1 Step')
+    field_2_Step: str = Field(..., alias='2 Step')
+
+
+class Recursive1(BaseModel):
+    value: float
+
+
+class Sub(BaseModel):
+    recursive: Recursive1
+
+
+class Recursive(BaseModel):
+    sub: Sub
+
+
+class Model(BaseModel):
+    Serial_Number: str = Field(..., alias='Serial Number')
+    Timestamp: str
+    Data_1: Data = Field(..., alias='Data')
+    values: Values
+    recursive: Recursive

tests/main/conftest.py

@@ -470,7 +470,11 @@ def run_main_and_assert(  # noqa: PLR0912
         assert_func(output_path, expected_file, transform=transform)
 
     if output_path is not None and not skip_code_validation:
-        _validate_output_files(output_path, extra_args, force_exec_validation=force_exec_validation)
+        normalized_extra_args = _normalize_extra_args(
+            extra_args,
+            default_output_model_type=default_output_model_type,
+        )
+        _validate_output_files(output_path, normalized_extra_args, force_exec_validation=force_exec_validation)
 
 
 def _parse_target_version(extra_arguments: Sequence[str] | None) -> tuple[int, int] | None:
@@ -500,7 +504,7 @@ def _should_skip_exec(extra_arguments: Sequence[str] | None, *, force_exec: bool
             When target > runtime, compile will be skipped entirely regardless of this flag.
     """
     output_model_type = _get_argument_value(extra_arguments, "--output-model-type")
-    is_pydantic_v1 = output_model_type is None or output_model_type == DataModelType.PydanticBaseModel.value
+    is_pydantic_v1 = output_model_type == DataModelType.PydanticBaseModel.value
     if (is_pydantic_v1 and is_pydantic_v2()) or (
         output_model_type in {DataModelType.PydanticV2BaseModel.value, DataModelType.PydanticV2Dataclass.value}
         and not is_pydantic_v2()
@@ -601,6 +605,7 @@ def run_main_url_and_assert(
     assert_func: AssertFileContent,
     expected_file: str | Path,
     extra_args: Sequence[str] | None = None,
+    default_output_model_type: str | None = DataModelType.PydanticBaseModel.value,
     transform: Callable[[str], str] | None = None,
     force_exec_validation: bool = False,
 ) -> None:
@@ -613,13 +618,26 @@ def run_main_url_and_assert(
         assert_func: The assert_file_content function to use for verification
         expected_file: Expected output filename
         extra_args: Additional CLI arguments
+        default_output_model_type: Output model type injected when extra_args omits
+            --output-model-type. Set to None for tests that intentionally validate
+            the real CLI default.
         transform: Optional function to transform output before comparison
         force_exec_validation: Run exec() even when target Python version differs from
             the test environment (only effective when target <= runtime).
     """
     __tracebackhide__ = True
-    return_code = _run_main_url(url, output_path, input_file_type, extra_args=extra_args)
+    return_code = _run_main_url(
+        url,
+        output_path,
+        input_file_type,
+        extra_args=extra_args,
+        default_output_model_type=default_output_model_type,
+    )
     _assert_exit_code(return_code, Exit.OK, f"URL: {url}")
     assert_func(output_path, expected_file, transform=transform)
 
-    _validate_output_files(output_path, extra_args, force_exec_validation=force_exec_validation)
+    normalized_extra_args = _normalize_extra_args(
+        extra_args,
+        default_output_model_type=default_output_model_type,
+    )
+    _validate_output_files(output_path, normalized_extra_args, force_exec_validation=force_exec_validation)

tests/main/jsonschema/test_main_jsonschema.py

@@ -2010,6 +2010,7 @@ def test_main_generate_from_directory(tmp_path: Path) -> None:
         input_=input_,
         input_file_type=InputFileType.JsonSchema,
         output=tmp_path,
+        output_model_type=DataModelType.PydanticBaseModel,
     )
 
     main_nested_directory = EXPECTED_JSON_SCHEMA_PATH / "nested_directory"

tests/main/openapi/test_main_openapi.py

@@ -1767,6 +1767,7 @@ def custom_class_name_generator(name: str) -> str:
             input_=input_,
             input_file_type=InputFileType.OpenAPI,
             output=output_path,
+            output_model_type=DataModelType.PydanticBaseModel,
             custom_class_name_generator=custom_class_name_generator,
         )
 

tests/main/test_main_general.py

@@ -112,6 +112,7 @@ def test_space_and_special_characters_dict(output_file: Path) -> None:
         output_path=output_file,
         input_file_type="dict",
         assert_func=assert_file_content,
+        expected_file="space_and_special_characters_dict_default_v2.py",
         default_output_model_type=None,
     )
 
@@ -1827,6 +1828,7 @@ def test_generate_returns_dict_for_multiple_modules(tmp_path: Path) -> None:
         tmp_path,
         input_file_type=InputFileType.JsonSchema,
         disable_timestamp=True,
+        output_model_type=DataModelType.PydanticBaseModel,
     )
 
     assert result == snapshot({

tests/main/test_public_api_signature_baseline.py

@@ -62,7 +62,7 @@ def _baseline_generate(
     input_filename: str | None = None,
     input_file_type: InputFileType = InputFileType.Auto,
     output: Path | None = None,
-    output_model_type: DataModelType = DataModelType.PydanticBaseModel,
+    output_model_type: DataModelType = DataModelType.PydanticV2BaseModel,
     target_python_version: PythonVersion = PythonVersionMin,
     target_pydantic_version: TargetPydanticVersion | None = None,
     base_class: str = "",