Add --use-serialization-alias option for Pydantic v2

docs/cli-reference/field-customization.md

@@ -26,6 +26,7 @@
 | [`--use-field-description-example`](#use-field-description-example) | Add field examples to docstrings. |
 | [`--use-inline-field-description`](#use-inline-field-description) | Add field descriptions as inline comments. |
 | [`--use-schema-description`](#use-schema-description) | Use schema description as class docstring. |
+| [`--use-serialization-alias`](#use-serialization-alias) | Use serialization_alias instead of alias for field aliasing ... |
 | [`--use-title-as-name`](#use-title-as-name) | Use schema title as the generated class name. |
 
 ---
@@ -3663,6 +3664,86 @@ useful for preserving documentation from your schema in the generated code.
 
 ---
 
+## `--use-serialization-alias` {#use-serialization-alias}
+
+Use serialization_alias instead of alias for field aliasing (Pydantic v2 only).
+
+The `--use-serialization-alias` flag changes field aliasing to use `serialization_alias`
+instead of `alias`. This allows setting values using the Pythonic field name while
+serializing to the original JSON property name.
+
+!!! tip "Usage"
+
+    ```bash
+    datamodel-codegen --input schema.json --use-serialization-alias --output-model-type pydantic_v2.BaseModel # (1)!
+    ```
+
+    1. :material-arrow-left: `--use-serialization-alias` - the option documented here
+
+??? example "Examples"
+
+    **Input Schema:**
+
+    ```json
+    {
+      "$schema": "http://json-schema.org/draft-07/schema#",
+      "title": "Person",
+      "type": "object",
+      "properties": {
+        "first-name": {
+          "type": "string"
+        },
+        "last-name": {
+          "type": "string"
+        },
+        "email_address": {
+          "type": "string"
+        }
+      },
+      "required": ["first-name", "last-name"]
+    }
+    ```
+
+    **Output:**
+
+    === "With Option"
+
+        ```python
+        # generated by datamodel-codegen:
+        #   filename:  no_alias.json
+        #   timestamp: 2019-07-26T00:00:00+00:00
+
+        from __future__ import annotations
+
+        from pydantic import BaseModel, Field
+
+
+        class Person(BaseModel):
+            first_name: str = Field(..., serialization_alias='first-name')
+            last_name: str = Field(..., serialization_alias='last-name')
+            email_address: str | None = None
+        ```
+
+    === "Without Option"
+
+        ```python
+        # generated by datamodel-codegen:
+        #   filename:  no_alias.json
+        #   timestamp: 2019-07-26T00:00:00+00:00
+
+        from __future__ import annotations
+
+        from pydantic import BaseModel, Field
+
+
+        class Person(BaseModel):
+            first_name: str = Field(..., alias='first-name')
+            last_name: str = Field(..., alias='last-name')
+            email_address: str | None = None
+        ```
+
+---
+
 ## `--use-title-as-name` {#use-title-as-name}
 
 Use schema title as the generated class name.

docs/cli-reference/index.md

@@ -10,7 +10,7 @@ This documentation is auto-generated from test cases.
 |----------|---------|-------------|
 | 📁 [Base Options](base-options.md) | 7 | Input/output configuration |
 | 🔧 [Typing Customization](typing-customization.md) | 27 | Type annotation and import behavior |
-| 🏷️ [Field Customization](field-customization.md) | 23 | Field naming and docstring behavior |
+| 🏷️ [Field Customization](field-customization.md) | 24 | Field naming and docstring behavior |
 | 🏗️ [Model Customization](model-customization.md) | 39 | Model generation behavior |
 | 🎨 [Template Customization](template-customization.md) | 18 | Output formatting and custom rendering |
 | 📘 [OpenAPI-only Options](openapi-only-options.md) | 7 | OpenAPI-specific features |
@@ -203,6 +203,7 @@ This documentation is auto-generated from test cases.
 - [`--use-pendulum`](typing-customization.md#use-pendulum)
 - [`--use-root-model-type-alias`](typing-customization.md#use-root-model-type-alias)
 - [`--use-schema-description`](field-customization.md#use-schema-description)
+- [`--use-serialization-alias`](field-customization.md#use-serialization-alias)
 - [`--use-serialize-as-any`](model-customization.md#use-serialize-as-any)
 - [`--use-specialized-enum`](typing-customization.md#use-specialized-enum)
 - [`--use-standard-collections`](typing-customization.md#use-standard-collections)

docs/cli-reference/quick-reference.md

@@ -82,6 +82,7 @@ datamodel-codegen [OPTIONS]
 | [`--use-field-description-example`](field-customization.md#use-field-description-example) | Add field examples to docstrings. |
 | [`--use-inline-field-description`](field-customization.md#use-inline-field-description) | Add field descriptions as inline comments. |
 | [`--use-schema-description`](field-customization.md#use-schema-description) | Use schema description as class docstring. |
+| [`--use-serialization-alias`](field-customization.md#use-serialization-alias) | Use serialization_alias instead of alias for field aliasing (Pydantic v2 only). |
 | [`--use-title-as-name`](field-customization.md#use-title-as-name) | Use schema title as the generated class name. |
 
 ### 🏗️ Model Customization
@@ -333,6 +334,7 @@ All options sorted alphabetically:
 - [`--use-pendulum`](typing-customization.md#use-pendulum) - Use pendulum types for date/time fields instead of datetime ...
 - [`--use-root-model-type-alias`](typing-customization.md#use-root-model-type-alias) - Generate RootModel as type alias format for better mypy supp...
 - [`--use-schema-description`](field-customization.md#use-schema-description) - Use schema description as class docstring.
+- [`--use-serialization-alias`](field-customization.md#use-serialization-alias) - Use serialization_alias instead of alias for field aliasing ...
 - [`--use-serialize-as-any`](model-customization.md#use-serialize-as-any) - Wrap fields with subtypes in Pydantic's SerializeAsAny.
 - [`--use-specialized-enum`](typing-customization.md#use-specialized-enum) - Generate StrEnum/IntEnum for string/integer enums (Python 3....
 - [`--use-standard-collections`](typing-customization.md#use-standard-collections) - Use built-in dict/list instead of typing.Dict/List.

src/datamodel_code_generator/__main__.py

@@ -595,6 +595,7 @@ def validate_class_name_affix_scope(cls, v: str | ClassNameAffixScope | None) ->
     frozen_dataclasses: bool = False
     dataclass_arguments: Optional[DataclassArguments] = None  # noqa: UP045
     no_alias: bool = False
+    use_serialization_alias: bool = False
     use_frozen_field: bool = False
     use_default_factory_for_optional_nested_models: bool = False
     formatters: list[Formatter] | None = None
@@ -1007,6 +1008,7 @@ def run_generate_from_config(  # noqa: PLR0913, PLR0917
         keyword_only=config.keyword_only,
         frozen_dataclasses=config.frozen_dataclasses,
         no_alias=config.no_alias,
+        use_serialization_alias=config.use_serialization_alias,
         use_frozen_field=config.use_frozen_field,
         use_default_factory_for_optional_nested_models=config.use_default_factory_for_optional_nested_models,
         formatters=config.formatters,

src/datamodel_code_generator/_types/generate_config_dict.py

@@ -147,6 +147,7 @@ class GenerateConfigDict(TypedDict):
     keyword_only: NotRequired[bool]
     frozen_dataclasses: NotRequired[bool]
     no_alias: NotRequired[bool]
+    use_serialization_alias: NotRequired[bool]
     use_frozen_field: NotRequired[bool]
     use_default_factory_for_optional_nested_models: NotRequired[bool]
     formatters: NotRequired[list[Formatter] | None]

src/datamodel_code_generator/_types/parser_config_dicts.py

@@ -134,6 +134,7 @@ class ParserConfigDict(TypedDict):
     keyword_only: NotRequired[bool]
     frozen_dataclasses: NotRequired[bool]
     no_alias: NotRequired[bool]
+    use_serialization_alias: NotRequired[bool]
     use_frozen_field: NotRequired[bool]
     use_default_factory_for_optional_nested_models: NotRequired[bool]
     formatters: NotRequired[list[Formatter] | None]

src/datamodel_code_generator/arguments.py

@@ -789,6 +789,13 @@ def start_section(self, heading: str | None) -> None:
     action="store_true",
     default=None,
 )
+field_options.add_argument(
+    "--use-serialization-alias",
+    help="Use serialization_alias instead of alias for field aliasing (Pydantic v2 only). "
+    "This allows setting values using the Pythonic field name while serializing to the original name.",
+    action="store_true",
+    default=None,
+)
 field_options.add_argument(
     "--use-frozen-field",
     help="Use Field(frozen=True) for readOnly fields (Pydantic v2) or Field(allow_mutation=False) (Pydantic v1)",

src/datamodel_code_generator/cli_options.py

@@ -142,6 +142,7 @@ class CLIOptionMeta:
     "--aliases": CLIOptionMeta(name="--aliases", category=OptionCategory.FIELD),
     "--default-values": CLIOptionMeta(name="--default-values", category=OptionCategory.FIELD),
     "--no-alias": CLIOptionMeta(name="--no-alias", category=OptionCategory.FIELD),
+    "--use-serialization-alias": CLIOptionMeta(name="--use-serialization-alias", category=OptionCategory.FIELD),
     "--use-title-as-name": CLIOptionMeta(name="--use-title-as-name", category=OptionCategory.FIELD),
     "--use-schema-description": CLIOptionMeta(name="--use-schema-description", category=OptionCategory.FIELD),
     "--use-field-description": CLIOptionMeta(name="--use-field-description", category=OptionCategory.FIELD),

src/datamodel_code_generator/config.py

@@ -184,6 +184,7 @@ class Config:
     keyword_only: bool = False
     frozen_dataclasses: bool = False
     no_alias: bool = False
+    use_serialization_alias: bool = False
     use_frozen_field: bool = False
     use_default_factory_for_optional_nested_models: bool = False
     formatters: list[Formatter] | None = None
@@ -318,6 +319,7 @@ class Config:
     keyword_only: bool = False
     frozen_dataclasses: bool = False
     no_alias: bool = False
+    use_serialization_alias: bool = False
     use_frozen_field: bool = False
     use_default_factory_for_optional_nested_models: bool = False
     formatters: list[Formatter] | None = None

src/datamodel_code_generator/model/base.py

@@ -191,6 +191,7 @@ class Config:
     read_only: bool = False
     write_only: bool = False
     use_frozen_field: bool = False
+    use_serialization_alias: bool = False
     use_default_factory_for_optional_nested_models: bool = False
 
     if not TYPE_CHECKING:  # pragma: no branch

src/datamodel_code_generator/model/pydantic_v2/base_model.py

@@ -158,6 +158,9 @@ def _process_data_in_str(self, data: dict[str, Any]) -> None:
             aliases_repr = ", ".join(repr(a) for a in self.validation_aliases)
             data["validation_alias"] = _RawRepr(f"AliasChoices({aliases_repr})")
 
+        if self.use_serialization_alias and "alias" in data:
+            data["serialization_alias"] = data.pop("alias")
+
         # **extra is not supported in pydantic 2.0
         json_schema_extra = {k: v for k, v in data.items() if k not in self._DEFAULT_FIELD_KEYS}
         if json_schema_extra:

src/datamodel_code_generator/parser/base.py

@@ -938,6 +938,7 @@ def __init__(  # noqa: PLR0912, PLR0915
         }
         self.read_only_write_only_model_type: ReadOnlyWriteOnlyModelType | None = config.read_only_write_only_model_type
         self.use_frozen_field: bool = config.use_frozen_field
+        self.use_serialization_alias: bool = config.use_serialization_alias
         self.use_default_factory_for_optional_nested_models: bool = (
             config.use_default_factory_for_optional_nested_models
         )
@@ -1463,6 +1464,7 @@ def check_paths(
                                 required=True,
                                 alias=single_alias,
                                 validation_aliases=validation_aliases,
+                                use_serialization_alias=self.use_serialization_alias,
                             )
                         )
             has_imported_literal = any(import_ == IMPORT_LITERAL for import_ in imports)

src/datamodel_code_generator/parser/graphql.py

@@ -198,6 +198,7 @@ def _typename_field(self, name: str) -> DataModelFieldBase:
             use_one_literal_as_default=True,
             use_default_kwarg=self.use_default_kwarg,
             has_default=True,
+            use_serialization_alias=self.use_serialization_alias,
         )
 
     def _get_default(  # noqa: PLR6301
@@ -417,6 +418,7 @@ def parse_field(
             use_default_kwarg=self.use_default_kwarg,
             original_name=field_name,
             has_default=effective_has_default,
+            use_serialization_alias=self.use_serialization_alias,
         )
 
     def parse_object_like(

src/datamodel_code_generator/parser/jsonschema.py

@@ -1083,6 +1083,7 @@ def get_object_field(  # noqa: PLR0913
             read_only=self._resolve_field_flag(field, "readOnly"),
             write_only=self._resolve_field_flag(field, "writeOnly"),
             use_frozen_field=self.use_frozen_field,
+            use_serialization_alias=self.use_serialization_alias,
             use_default_factory_for_optional_nested_models=self.use_default_factory_for_optional_nested_models,
         )
 
@@ -2221,6 +2222,7 @@ def _parse_all_of_item(  # noqa: PLR0912, PLR0913, PLR0915, PLR0917
                                     alias=single_alias,
                                     validation_aliases=validation_aliases,
                                     data_type=data_type,
+                                    use_serialization_alias=self.use_serialization_alias,
                                 )
                             )
                             existing_field_names.update({request, field_name})

src/datamodel_code_generator/parser/openapi.py

@@ -629,6 +629,7 @@ def parse_all_parameters(  # noqa: PLR0912, PLR0914
                         original_name=parameter_name,
                         has_default=effective_has_default,
                         type_has_null=object_schema.type_has_null if object_schema else None,
+                        use_serialization_alias=self.use_serialization_alias,
                     )
                 )
 

src/datamodel_code_generator/prompt_data.py

@@ -129,6 +129,7 @@
     "--use-pendulum": "Use pendulum types for date/time fields instead of datetime module.",
     "--use-root-model-type-alias": "Generate RootModel as type alias format for better mypy support.",
     "--use-schema-description": "Use schema description as class docstring.",
+    "--use-serialization-alias": "Use serialization_alias instead of alias for field aliasing (Pydantic v2 only).",
     "--use-serialize-as-any": "Wrap fields with subtypes in Pydantic's SerializeAsAny.",
     "--use-specialized-enum": "Generate StrEnum/IntEnum for string/integer enums (Python 3.11+).",
     "--use-standard-collections": "Use built-in dict/list instead of typing.Dict/List.",

tests/data/expected/main/input_model/config_class.py

@@ -222,6 +222,7 @@ class GenerateConfig(TypedDict):
     keyword_only: NotRequired[bool]
     frozen_dataclasses: NotRequired[bool]
     no_alias: NotRequired[bool]
+    use_serialization_alias: NotRequired[bool]
     use_frozen_field: NotRequired[bool]
     use_default_factory_for_optional_nested_models: NotRequired[bool]
     formatters: NotRequired[list[Formatter] | None]

tests/data/expected/main_kr/use_serialization_alias/output.py

@@ -0,0 +1,13 @@
+# generated by datamodel-codegen:
+#   filename:  no_alias.json
+#   timestamp: 2019-07-26T00:00:00+00:00
+
+from __future__ import annotations
+
+from pydantic import BaseModel, Field
+
+
+class Person(BaseModel):
+    first_name: str = Field(..., serialization_alias='first-name')
+    last_name: str = Field(..., serialization_alias='last-name')
+    email_address: str | None = None

tests/main/test_public_api_signature_baseline.py

@@ -167,6 +167,7 @@ def _baseline_generate(
     keyword_only: bool = False,
     frozen_dataclasses: bool = False,
     no_alias: bool = False,
+    use_serialization_alias: bool = False,
     use_frozen_field: bool = False,
     use_default_factory_for_optional_nested_models: bool = False,
     formatters: list[Formatter] | None = None,
@@ -295,6 +296,7 @@ def __init__(
         keyword_only: bool = False,
         frozen_dataclasses: bool = False,
         no_alias: bool = False,
+        use_serialization_alias: bool = False,
         use_frozen_field: bool = False,
         use_default_factory_for_optional_nested_models: bool = False,
         formatters: list[Formatter] | None = None,

tests/test_main_kr.py

@@ -1358,6 +1358,36 @@ def test_no_alias(output_file: Path) -> None:
     )
 
 
+@pytest.mark.cli_doc(
+    options=["--use-serialization-alias"],
+    option_description="""Use serialization_alias instead of alias for field aliasing (Pydantic v2 only).
+
+The `--use-serialization-alias` flag changes field aliasing to use `serialization_alias`
+instead of `alias`. This allows setting values using the Pythonic field name while
+serializing to the original JSON property name.""",
+    input_schema="jsonschema/no_alias.json",
+    cli_args=["--use-serialization-alias", "--output-model-type", "pydantic_v2.BaseModel"],
+    golden_output="main_kr/use_serialization_alias/output.py",
+    comparison_output="main_kr/no_alias/without_option.py",
+)
+@freeze_time("2019-07-26")
+def test_use_serialization_alias(output_file: Path) -> None:
+    """Use serialization_alias instead of alias for field aliasing (Pydantic v2 only).
+
+    The `--use-serialization-alias` flag changes field aliasing to use `serialization_alias`
+    instead of `alias`. This allows setting values using the Pythonic field name while
+    serializing to the original JSON property name.
+    """
+    run_main_and_assert(
+        input_path=JSON_SCHEMA_DATA_PATH / "no_alias.json",
+        output_path=output_file,
+        input_file_type="jsonschema",
+        assert_func=assert_file_content,
+        expected_file=EXPECTED_MAIN_KR_PATH / "use_serialization_alias" / "output.py",
+        extra_args=["--use-serialization-alias", "--output-model-type", "pydantic_v2.BaseModel"],
+    )
+
+
 @pytest.mark.cli_doc(
     options=["--custom-file-header"],
     option_description="""Add custom header text to the generated file.