Add --field-type-collision-strategy option

docs/cli-reference/field-customization.md

@@ -12,6 +12,7 @@
 | [`--field-extra-keys`](#field-extra-keys) | Include specific extra keys in Field() definitions. |
 | [`--field-extra-keys-without-x-prefix`](#field-extra-keys-without-x-prefix) | Include specified schema extension keys in Field() without r... |
 | [`--field-include-all-keys`](#field-include-all-keys) | Include all schema keys in Field() json_schema_extra. |
+| [`--field-type-collision-strategy`](#field-type-collision-strategy) | Rename type class instead of field when names collide (Pydan... |
 | [`--no-alias`](#no-alias) | Disable Field alias generation for non-Python-safe property ... |
 | [`--original-field-name-delimiter`](#original-field-name-delimiter) | Specify delimiter for original field names when using snake-... |
 | [`--remove-special-field-name-prefix`](#remove-special-field-name-prefix) | Remove the special prefix from field names. |
@@ -1813,6 +1814,66 @@ The `--field-include-all-keys` flag configures the code generation behavior.
 
 ---
 
+## `--field-type-collision-strategy` {#field-type-collision-strategy}
+
+Rename type class instead of field when names collide (Pydantic v2 only).
+
+The `--field-type-collision-strategy` flag controls how field name and type name
+collisions are resolved. With `rename-type`, the type class is renamed with a suffix
+to preserve the original field name, instead of renaming the field and adding an alias.
+
+!!! tip "Usage"
+
+    ```bash
+    datamodel-codegen --input schema.json --output-model-type pydantic_v2.BaseModel --field-type-collision-strategy rename-type # (1)!
+    ```
+
+    1. :material-arrow-left: `--field-type-collision-strategy` - the option documented here
+
+??? example "Examples"
+
+    **Input Schema:**
+
+    ```json
+    {
+      "title": "Test",
+      "type": "object",
+      "properties": {
+        "TestObject": {
+          "title": "TestObject",
+          "type": "object",
+          "properties": {
+            "test_string": {
+              "type": "string"
+            }
+          }
+        }
+      }
+    }
+    ```
+
+    **Output:**
+
+    ```python
+    # generated by datamodel-codegen:
+    #   filename:  field_has_same_name.json
+    #   timestamp: 2019-07-26T00:00:00+00:00
+
+    from __future__ import annotations
+
+    from pydantic import BaseModel, Field
+
+
+    class TestObject_1(BaseModel):
+        test_string: str | None = None
+
+
+    class Test(BaseModel):
+        TestObject: TestObject_1 | None = Field(None, title='TestObject')
+    ```
+
+---
+
 ## `--no-alias` {#no-alias}
 
 Disable Field alias generation for non-Python-safe property names.

docs/cli-reference/index.md

@@ -10,7 +10,7 @@ This documentation is auto-generated from test cases.
 |----------|---------|-------------|
 | 📁 [Base Options](base-options.md) | 5 | Input/output configuration |
 | 🔧 [Typing Customization](typing-customization.md) | 17 | Type annotation and import behavior |
-| 🏷️ [Field Customization](field-customization.md) | 20 | Field naming and docstring behavior |
+| 🏷️ [Field Customization](field-customization.md) | 21 | Field naming and docstring behavior |
 | 🏗️ [Model Customization](model-customization.md) | 29 | Model generation behavior |
 | 🎨 [Template Customization](template-customization.md) | 16 | Output formatting and custom rendering |
 | 📘 [OpenAPI-only Options](openapi-only-options.md) | 6 | OpenAPI-specific features |
@@ -75,6 +75,7 @@ This documentation is auto-generated from test cases.
 - [`--field-extra-keys`](field-customization.md#field-extra-keys)
 - [`--field-extra-keys-without-x-prefix`](field-customization.md#field-extra-keys-without-x-prefix)
 - [`--field-include-all-keys`](field-customization.md#field-include-all-keys)
+- [`--field-type-collision-strategy`](field-customization.md#field-type-collision-strategy)
 - [`--force-optional`](model-customization.md#force-optional)
 - [`--formatters`](template-customization.md#formatters)
 - [`--frozen-dataclasses`](model-customization.md#frozen-dataclasses)

docs/cli-reference/quick-reference.md

@@ -56,6 +56,7 @@ datamodel-codegen [OPTIONS]
 | [`--field-extra-keys`](field-customization.md#field-extra-keys) | Include specific extra keys in Field() definitions. |
 | [`--field-extra-keys-without-x-prefix`](field-customization.md#field-extra-keys-without-x-prefix) | Include specified schema extension keys in Field() without requiring 'x-' prefix... |
 | [`--field-include-all-keys`](field-customization.md#field-include-all-keys) | Include all schema keys in Field() json_schema_extra. |
+| [`--field-type-collision-strategy`](field-customization.md#field-type-collision-strategy) | Rename type class instead of field when names collide (Pydantic v2 only). |
 | [`--no-alias`](field-customization.md#no-alias) | Disable Field alias generation for non-Python-safe property names. |
 | [`--original-field-name-delimiter`](field-customization.md#original-field-name-delimiter) | Specify delimiter for original field names when using snake-case conversion. |
 | [`--remove-special-field-name-prefix`](field-customization.md#remove-special-field-name-prefix) | Remove the special prefix from field names. |
@@ -206,6 +207,7 @@ All options sorted alphabetically:
 - [`--field-extra-keys`](field-customization.md#field-extra-keys) - Include specific extra keys in Field() definitions.
 - [`--field-extra-keys-without-x-prefix`](field-customization.md#field-extra-keys-without-x-prefix) - Include specified schema extension keys in Field() without r...
 - [`--field-include-all-keys`](field-customization.md#field-include-all-keys) - Include all schema keys in Field() json_schema_extra.
+- [`--field-type-collision-strategy`](field-customization.md#field-type-collision-strategy) - Rename type class instead of field when names collide (Pydan...
 - [`--force-optional`](model-customization.md#force-optional) - Force all fields to be Optional regardless of required statu...
 - [`--formatters`](template-customization.md#formatters) - Specify code formatters to apply to generated output.
 - [`--frozen-dataclasses`](model-customization.md#frozen-dataclasses) - Generate frozen dataclasses with optional keyword-only field...

src/datamodel_code_generator/__init__.py

@@ -270,6 +270,17 @@ class AllExportsCollisionStrategy(Enum):
     FullPrefix = "full-prefix"
 
 
+class FieldTypeCollisionStrategy(Enum):
+    """Strategy for handling field name and type name collisions.
+
+    rename_field: Rename the field with a suffix and add alias (default).
+    rename_type: Rename the type class with a suffix to preserve field name.
+    """
+
+    RenameField = "rename-field"
+    RenameType = "rename-type"
+
+
 class AllOfMergeMode(Enum):
     """Mode for field merging in allOf schemas.
 
@@ -484,6 +495,7 @@ def generate(  # noqa: PLR0912, PLR0913, PLR0914, PLR0915
     use_status_code_in_response_name: bool = False,
     all_exports_scope: AllExportsScope | None = None,
     all_exports_collision_strategy: AllExportsCollisionStrategy | None = None,
+    field_type_collision_strategy: FieldTypeCollisionStrategy | None = None,
     module_split_mode: ModuleSplitMode | None = None,
 ) -> None:
     """Generate Python data models from schema definitions or structured data.
@@ -730,6 +742,7 @@ def get_header_and_first_line(csv_file: IO[str]) -> dict[str, Any]:
         dataclass_arguments=dataclass_arguments,
         type_mappings=type_mappings,
         read_only_write_only_model_type=read_only_write_only_model_type,
+        field_type_collision_strategy=field_type_collision_strategy,
         **kwargs,
     )
 

src/datamodel_code_generator/__main__.py

@@ -28,6 +28,7 @@
     DataclassArguments,
     DataModelType,
     Error,
+    FieldTypeCollisionStrategy,
     InputFileType,
     InvalidClassNameError,
     ModuleSplitMode,
@@ -470,6 +471,7 @@ def validate_all_exports_collision_strategy(cls, values: dict[str, Any]) -> dict
     use_status_code_in_response_name: bool = False
     all_exports_scope: Optional[AllExportsScope] = None  # noqa: UP045
     all_exports_collision_strategy: Optional[AllExportsCollisionStrategy] = None  # noqa: UP045
+    field_type_collision_strategy: Optional[FieldTypeCollisionStrategy] = None  # noqa: UP045
     module_split_mode: Optional[ModuleSplitMode] = None  # noqa: UP045
     watch: bool = False
     watch_delay: float = 0.5
@@ -777,6 +779,7 @@ def run_generate_from_config(  # noqa: PLR0913, PLR0917
         use_status_code_in_response_name=config.use_status_code_in_response_name,
         all_exports_scope=config.all_exports_scope,
         all_exports_collision_strategy=config.all_exports_collision_strategy,
+        field_type_collision_strategy=config.field_type_collision_strategy,
         module_split_mode=config.module_split_mode,
     )
 

src/datamodel_code_generator/arguments.py

@@ -21,6 +21,7 @@
     AllOfMergeMode,
     DataclassArguments,
     DataModelType,
+    FieldTypeCollisionStrategy,
     InputFileType,
     ModuleSplitMode,
     OpenAPIScope,
@@ -621,6 +622,14 @@ def start_section(self, heading: str | None) -> None:
     action="store_true",
     default=None,
 )
+field_options.add_argument(
+    "--field-type-collision-strategy",
+    help="Strategy for handling field name and type name collisions (Pydantic v2 only). "
+    "'rename-field': rename field with suffix and add alias (default). "
+    "'rename-type': rename type class with suffix to preserve field name.",
+    choices=[s.value for s in FieldTypeCollisionStrategy],
+    default=None,
+)
 
 # ======================================================================================
 # Options for templating output

src/datamodel_code_generator/cli_options.py

@@ -135,6 +135,9 @@ class CLIOptionMeta:
     "--use-enum-values-in-discriminator": CLIOptionMeta(
         name="--use-enum-values-in-discriminator", category=OptionCategory.FIELD
     ),
+    "--field-type-collision-strategy": CLIOptionMeta(
+        name="--field-type-collision-strategy", category=OptionCategory.FIELD
+    ),
     # ==========================================================================
     # Typing Customization
     # ==========================================================================

src/datamodel_code_generator/parser/base.py

@@ -28,6 +28,7 @@
     AllExportsScope,
     AllOfMergeMode,
     Error,
+    FieldTypeCollisionStrategy,
     ModuleSplitMode,
     ReadOnlyWriteOnlyModelType,
     ReuseScope,
@@ -770,6 +771,7 @@ def __init__(  # noqa: PLR0912, PLR0913, PLR0915
         dataclass_arguments: DataclassArguments | None = None,
         type_mappings: list[str] | None = None,
         read_only_write_only_model_type: ReadOnlyWriteOnlyModelType | None = None,
+        field_type_collision_strategy: FieldTypeCollisionStrategy | None = None,
     ) -> None:
         """Initialize the Parser with configuration options."""
         self.keyword_only = keyword_only
@@ -926,6 +928,7 @@ def __init__(  # noqa: PLR0912, PLR0913, PLR0915
         self.read_only_write_only_model_type: ReadOnlyWriteOnlyModelType | None = read_only_write_only_model_type
         self.use_frozen_field: bool = use_frozen_field
         self.use_default_factory_for_optional_nested_models: bool = use_default_factory_for_optional_nested_models
+        self.field_type_collision_strategy: FieldTypeCollisionStrategy | None = field_type_collision_strategy
 
     @property
     def field_name_model_type(self) -> ModelType:
@@ -1844,22 +1847,47 @@ def __change_field_name(
     ) -> None:
         if not self.data_model_type.SUPPORTS_FIELD_RENAMING:
             return
+
+        rename_type = self.field_type_collision_strategy == FieldTypeCollisionStrategy.RenameType
+        all_class_names = {cast("str", m.class_name) for m in models if m.class_name}
+
         for model in models:
-            if "Enum" in model.base_class:
-                continue
-            if not model.BASE_CLASS:
+            if "Enum" in model.base_class or not model.BASE_CLASS:
                 continue
 
             for field in model.fields:
                 filed_name = field.name
-                filed_name_resolver = ModelResolver(snake_case_field=self.snake_case_field, remove_suffix_number=True)
+                reference_type_names: set[str] = set()
+                colliding_reference: Reference | None = None
+
                 for data_type in field.data_type.all_data_types:
-                    if data_type.reference:
-                        filed_name_resolver.exclude_names.add(data_type.reference.short_name)
-                new_filed_name = filed_name_resolver.add(["field"], cast("str", filed_name)).name
-                if filed_name != new_filed_name:
-                    field.alias = filed_name
-                    field.name = new_filed_name
+                    if not data_type.reference:
+                        continue
+                    reference_type_names.add(data_type.reference.short_name)
+                    if rename_type and colliding_reference is None and data_type.reference.short_name == filed_name:
+                        colliding_reference = data_type.reference
+
+                if colliding_reference is not None:
+                    resolver = ModelResolver(
+                        exclude_names=all_class_names.copy(),
+                        snake_case_field=self.snake_case_field,
+                        remove_suffix_number=True,
+                    )
+                    source = cast("DataModel", colliding_reference.source)
+                    resolver.exclude_names.add(cast("str", filed_name))
+                    new_class_name = resolver.add(["type"], cast("str", source.class_name)).name
+                    source.class_name = new_class_name
+                    all_class_names.add(new_class_name)
+                elif not rename_type:
+                    resolver = ModelResolver(
+                        exclude_names=reference_type_names,
+                        snake_case_field=self.snake_case_field,
+                        remove_suffix_number=True,
+                    )
+                    new_filed_name = resolver.add(["field"], cast("str", filed_name)).name
+                    if filed_name != new_filed_name:
+                        field.alias = filed_name
+                        field.name = new_filed_name
 
     def __set_one_literal_on_default(self, models: list[DataModel]) -> None:
         if not self.use_one_literal_as_default:

src/datamodel_code_generator/parser/graphql.py

@@ -18,6 +18,7 @@
     AllOfMergeMode,
     DataclassArguments,
     DefaultPutDict,
+    FieldTypeCollisionStrategy,
     LiteralType,
     PythonVersion,
     PythonVersionMin,
@@ -193,6 +194,7 @@ def __init__(  # noqa: PLR0913
         use_serialize_as_any: bool = False,
         use_frozen_field: bool = False,
         use_default_factory_for_optional_nested_models: bool = False,
+        field_type_collision_strategy: FieldTypeCollisionStrategy | None = None,
     ) -> None:
         """Initialize the GraphQL parser with configuration options."""
         super().__init__(
@@ -290,6 +292,7 @@ def __init__(  # noqa: PLR0913
             use_serialize_as_any=use_serialize_as_any,
             use_frozen_field=use_frozen_field,
             use_default_factory_for_optional_nested_models=use_default_factory_for_optional_nested_models,
+            field_type_collision_strategy=field_type_collision_strategy,
         )
 
         self.data_model_scalar_type = data_model_scalar_type

src/datamodel_code_generator/parser/jsonschema.py

@@ -25,6 +25,7 @@
     DEFAULT_SHARED_MODULE_NAME,
     AllOfMergeMode,
     DataclassArguments,
+    FieldTypeCollisionStrategy,
     InvalidClassNameError,
     ReadOnlyWriteOnlyModelType,
     ReuseScope,
@@ -605,6 +606,7 @@ def __init__(  # noqa: PLR0913
         dataclass_arguments: DataclassArguments | None = None,
         type_mappings: list[str] | None = None,
         read_only_write_only_model_type: ReadOnlyWriteOnlyModelType | None = None,
+        field_type_collision_strategy: FieldTypeCollisionStrategy | None = None,
     ) -> None:
         """Initialize the JSON Schema parser with configuration options."""
         target_datetime_class = target_datetime_class or DatetimeClassType.Awaredatetime
@@ -703,6 +705,7 @@ def __init__(  # noqa: PLR0913
             dataclass_arguments=dataclass_arguments,
             type_mappings=type_mappings,
             read_only_write_only_model_type=read_only_write_only_model_type,
+            field_type_collision_strategy=field_type_collision_strategy,
         )
 
         self.remote_object_cache: DefaultPutDict[str, dict[str, YamlValue]] = DefaultPutDict()

src/datamodel_code_generator/parser/openapi.py

@@ -22,6 +22,7 @@
     AllOfMergeMode,
     DataclassArguments,
     Error,
+    FieldTypeCollisionStrategy,
     LiteralType,
     OpenAPIScope,
     PythonVersion,
@@ -277,6 +278,7 @@ def __init__(  # noqa: PLR0913
         use_frozen_field: bool = False,
         use_default_factory_for_optional_nested_models: bool = False,
         use_status_code_in_response_name: bool = False,
+        field_type_collision_strategy: FieldTypeCollisionStrategy | None = None,
     ) -> None:
         """Initialize the OpenAPI parser with extensive configuration options."""
         target_datetime_class = target_datetime_class or DatetimeClassType.Awaredatetime
@@ -375,6 +377,7 @@ def __init__(  # noqa: PLR0913
             read_only_write_only_model_type=read_only_write_only_model_type,
             use_frozen_field=use_frozen_field,
             use_default_factory_for_optional_nested_models=use_default_factory_for_optional_nested_models,
+            field_type_collision_strategy=field_type_collision_strategy,
         )
         self.open_api_scopes: list[OpenAPIScope] = openapi_scopes or [OpenAPIScope.Schemas]
         self.include_path_parameters: bool = include_path_parameters

tests/data/expected/main/jsonschema/field_has_same_name_rename_type.py

@@ -0,0 +1,15 @@
+# generated by datamodel-codegen:
+#   filename:  field_has_same_name.json
+#   timestamp: 2019-07-26T00:00:00+00:00
+
+from __future__ import annotations
+
+from pydantic import BaseModel, Field
+
+
+class TestObject_1(BaseModel):
+    test_string: str | None = None
+
+
+class Test(BaseModel):
+    TestObject: TestObject_1 | None = Field(None, title='TestObject')

tests/data/expected/main/jsonschema/field_type_collision_rename_type_double.py

@@ -0,0 +1,22 @@
+# generated by datamodel-codegen:
+#   filename:  field_type_collision_rename_type_double.json
+#   timestamp: 2019-07-26T00:00:00+00:00
+
+from __future__ import annotations
+
+from enum import Enum
+
+from pydantic import BaseModel
+
+
+class Status_1(Enum):
+    pending = 'pending'
+    confirmed = 'confirmed'
+
+
+class Status1(BaseModel):
+    code: int | None = None
+
+
+class Order(BaseModel):
+    Status: Status_1 | None = None