Fix Pydantic v2 deprecation warnings

docs/cli-reference/index.md

@@ -11,7 +11,7 @@ This documentation is auto-generated from test cases.
 | 📁 [Base Options](base-options.md) | 5 | Input/output configuration |
 | 🔧 [Typing Customization](typing-customization.md) | 19 | Type annotation and import behavior |
 | 🏷️ [Field Customization](field-customization.md) | 21 | Field naming and docstring behavior |
-| 🏗️ [Model Customization](model-customization.md) | 29 | Model generation behavior |
+| 🏗️ [Model Customization](model-customization.md) | 30 | 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 |
 | ⚙️ [General Options](general-options.md) | 14 | Utilities and meta options |
@@ -152,6 +152,7 @@ This documentation is auto-generated from test cases.
 
 ### T {#t}
 
+- [`--target-pydantic-version`](model-customization.md#target-pydantic-version)
 - [`--target-python-version`](model-customization.md#target-python-version)
 - [`--type-mappings`](typing-customization.md#type-mappings)
 

docs/cli-reference/model-customization.md

@@ -23,6 +23,7 @@
 | [`--skip-root-model`](#skip-root-model) | Skip generation of root model when schema contains nested de... |
 | [`--strict-nullable`](#strict-nullable) | Treat default field as a non-nullable field. |
 | [`--strip-default-none`](#strip-default-none) | Remove fields with None as default value from generated mode... |
+| [`--target-pydantic-version`](#target-pydantic-version) | Target Pydantic version for generated code compatibility. |
 | [`--target-python-version`](#target-python-version) | Target Python version for generated code syntax and imports.... |
 | [`--union-mode`](#union-mode) | Union mode for combining anyOf/oneOf schemas (smart or left_... |
 | [`--use-default`](#use-default) | Use default values from schema in generated models. |
@@ -4647,6 +4648,87 @@ default to None.
 
 ---
 
+## `--target-pydantic-version` {#target-pydantic-version}
+
+Target Pydantic version for generated code compatibility.
+
+The `--target-pydantic-version` flag controls Pydantic version-specific config:
+
+- **2**: Uses `populate_by_name=True` (compatible with Pydantic 2.0-2.10)
+- **2.11**: Uses `validate_by_name=True` (for Pydantic 2.11+)
+
+This prevents breaking changes when generated code is used on older Pydantic versions.
+
+!!! tip "Usage"
+
+    ```bash
+    datamodel-codegen --input schema.json --target-pydantic-version 2.11 --allow-population-by-field-name --output-model-type pydantic_v2.BaseModel # (1)!
+    ```
+
+    1. :material-arrow-left: `--target-pydantic-version` - the option documented here
+
+??? example "Examples"
+
+    **Input Schema:**
+
+    ```json
+    {
+      "$schema": "http://json-schema.org/draft-07/schema#",
+      "title": "Person",
+      "type": "object",
+      "properties": {
+        "firstName": {
+          "type": "string",
+          "description": "The person's first name."
+        },
+        "lastName": {
+          "type": ["string", "null"],
+          "description": "The person's last name."
+        },
+        "age": {
+          "description": "Age in years which must be equal to or greater than zero.",
+          "type": "integer",
+          "minimum": 0
+        },
+        "friends": {
+          "type": "array"
+        },
+        "comment": {
+          "type": "null"
+        }
+      }
+    }
+    ```
+
+    **Output:**
+
+    ```python
+    # generated by datamodel-codegen:
+    #   filename:  person.json
+    #   timestamp: 2019-07-26T00:00:00+00:00
+
+    from __future__ import annotations
+
+    from typing import Any
+
+    from pydantic import BaseModel, ConfigDict, Field, conint
+
+
+    class Person(BaseModel):
+        model_config = ConfigDict(
+            validate_by_name=True,
+        )
+        firstName: str | None = Field(None, description="The person's first name.")
+        lastName: str | None = Field(None, description="The person's last name.")
+        age: conint(ge=0) | None = Field(
+            None, description='Age in years which must be equal to or greater than zero.'
+        )
+        friends: list[Any] | None = None
+        comment: None = None
+    ```
+
+---
+
 ## `--target-python-version` {#target-python-version}
 
 Target Python version for generated code syntax and imports.

docs/cli-reference/quick-reference.md

@@ -95,6 +95,7 @@ datamodel-codegen [OPTIONS]
 | [`--skip-root-model`](model-customization.md#skip-root-model) | Skip generation of root model when schema contains nested definitions. |
 | [`--strict-nullable`](model-customization.md#strict-nullable) | Treat default field as a non-nullable field. |
 | [`--strip-default-none`](model-customization.md#strip-default-none) | Remove fields with None as default value from generated models. |
+| [`--target-pydantic-version`](model-customization.md#target-pydantic-version) | Target Pydantic version for generated code compatibility. |
 | [`--target-python-version`](model-customization.md#target-python-version) | Target Python version for generated code syntax and imports. |
 | [`--union-mode`](model-customization.md#union-mode) | Union mode for combining anyOf/oneOf schemas (smart or left_to_right). |
 | [`--use-default`](model-customization.md#use-default) | Use default values from schema in generated models. |
@@ -253,6 +254,7 @@ All options sorted alphabetically:
 - [`--strict-nullable`](model-customization.md#strict-nullable) - Treat default field as a non-nullable field.
 - [`--strict-types`](typing-customization.md#strict-types) - Enable strict type validation for specified Python types.
 - [`--strip-default-none`](model-customization.md#strip-default-none) - Remove fields with None as default value from generated mode...
+- [`--target-pydantic-version`](model-customization.md#target-pydantic-version) - Target Pydantic version for generated code compatibility.
 - [`--target-python-version`](model-customization.md#target-python-version) - Target Python version for generated code syntax and imports.
 - [`--type-mappings`](typing-customization.md#type-mappings) - Override default type mappings for schema formats.
 - [`--union-mode`](model-customization.md#union-mode) - Union mode for combining anyOf/oneOf schemas (smart or left_...

pyproject.toml

@@ -211,10 +211,6 @@ skip = '.git,*.lock,tests,docs/cli-reference,CHANGELOG.md,docs/changelog.md'
 [tool.pytest.ini_options]
 filterwarnings = [
   "error",
-  "ignore:^.*The `parse_obj` method is deprecated; use `model_validate` instead.*",
-  "ignore:^.*The `__fields_set__` attribute is deprecated, use `model_fields_set` instead.*",
-  "ignore:^.*The `dict` method is deprecated; use `model_dump` instead.*",
-  "ignore:^.*The `copy` method is deprecated; use `model_copy` instead.*",
   "ignore:^.*`--validation` option is deprecated.*",
   "ignore:^.*Field name `name` is duplicated on Pet.*",
   "ignore:^.*format of 'unknown-type' not understood for 'string' - using default.*",

src/datamodel_code_generator/__init__.py

@@ -322,6 +322,17 @@ class ModuleSplitMode(Enum):
     Single = "single"
 
 
+class TargetPydanticVersion(Enum):
+    """Target Pydantic version for generated code.
+
+    V2: Generate code compatible with Pydantic 2.0+ (uses populate_by_name).
+    V2_11: Generate code for Pydantic 2.11+ (uses validate_by_name).
+    """
+
+    V2 = "2"
+    V2_11 = "2.11"
+
+
 class Error(Exception):
     """Base exception for datamodel-code-generator errors."""
 
@@ -400,6 +411,7 @@ def generate(  # noqa: PLR0912, PLR0913, PLR0914, PLR0915
     output: Path | None = None,
     output_model_type: DataModelType = DataModelType.PydanticBaseModel,
     target_python_version: PythonVersion = PythonVersionMin,
+    target_pydantic_version: TargetPydanticVersion | None = None,
     base_class: str = "",
     additional_imports: list[str] | None = None,
     custom_template_dir: Path | None = None,
@@ -749,6 +761,7 @@ def get_header_and_first_line(csv_file: IO[str]) -> dict[str, Any]:
         type_mappings=type_mappings,
         read_only_write_only_model_type=read_only_write_only_model_type,
         field_type_collision_strategy=field_type_collision_strategy,
+        target_pydantic_version=target_pydantic_version,
         **kwargs,
     )
 
@@ -902,5 +915,6 @@ def infer_input_type(text: str) -> InputFileType:
     "ModuleSplitMode",
     "PythonVersion",
     "ReadOnlyWriteOnlyModelType",
+    "TargetPydanticVersion",
     "generate",
 ]

src/datamodel_code_generator/__main__.py

@@ -35,6 +35,7 @@
     OpenAPIScope,
     ReadOnlyWriteOnlyModelType,
     ReuseScope,
+    TargetPydanticVersion,
     enable_debug_message,
     generate,
 )
@@ -378,6 +379,7 @@ def validate_all_exports_collision_strategy(cls, values: dict[str, Any]) -> dict
     debug: bool = False
     disable_warnings: bool = False
     target_python_version: PythonVersion = PythonVersionMin
+    target_pydantic_version: Optional[TargetPydanticVersion] = None  # noqa: UP045
     base_class: str = ""
     additional_imports: Optional[list[str]] = None  # noqa: UP045
     custom_template_dir: Optional[Path] = None  # noqa: UP045
@@ -687,6 +689,7 @@ def run_generate_from_config(  # noqa: PLR0913, PLR0917
         output=output,
         output_model_type=config.output_model_type,
         target_python_version=config.target_python_version,
+        target_pydantic_version=config.target_pydantic_version,
         base_class=config.base_class,
         additional_imports=config.additional_imports,
         custom_template_dir=config.custom_template_dir,

src/datamodel_code_generator/arguments.py

@@ -27,6 +27,7 @@
     OpenAPIScope,
     ReadOnlyWriteOnlyModelType,
     ReuseScope,
+    TargetPydanticVersion,
 )
 from datamodel_code_generator.format import DateClassType, DatetimeClassType, Formatter, PythonVersion
 from datamodel_code_generator.model.pydantic_v2 import UnionMode
@@ -271,6 +272,14 @@ def start_section(self, heading: str | None) -> None:
     help="target python version",
     choices=[v.value for v in PythonVersion],
 )
+model_options.add_argument(
+    "--target-pydantic-version",
+    help="Target Pydantic version for generated code. "
+    "'2': Pydantic 2.0+ compatible (default, uses populate_by_name). "
+    "'2.11': Pydantic 2.11+ (uses validate_by_name).",
+    choices=[v.value for v in TargetPydanticVersion],
+    default=None,
+)
 model_options.add_argument(
     "--treat-dot-as-module",
     help="Treat dotted schema names as module paths, creating nested directory structures (e.g., 'foo.bar.Model' "

src/datamodel_code_generator/cli_options.py

@@ -71,6 +71,7 @@ class CLIOptionMeta:
     # ==========================================================================
     "--output-model-type": CLIOptionMeta(name="--output-model-type", category=OptionCategory.MODEL),
     "--target-python-version": CLIOptionMeta(name="--target-python-version", category=OptionCategory.MODEL),
+    "--target-pydantic-version": CLIOptionMeta(name="--target-pydantic-version", category=OptionCategory.MODEL),
     "--base-class": CLIOptionMeta(name="--base-class", category=OptionCategory.MODEL),
     "--class-name": CLIOptionMeta(name="--class-name", category=OptionCategory.MODEL),
     "--frozen-dataclasses": CLIOptionMeta(name="--frozen-dataclasses", category=OptionCategory.MODEL),

src/datamodel_code_generator/model/base.py

@@ -37,7 +37,7 @@
     chain_as_tuple,
     get_optional_type,
 )
-from datamodel_code_generator.util import PYDANTIC_V2, ConfigDict
+from datamodel_code_generator.util import PYDANTIC_V2, ConfigDict, model_copy, model_dump, model_validate
 
 __all__ = ["WrappedDefault"]
 
@@ -90,31 +90,34 @@ class Config:
     @cached_property
     def has_constraints(self) -> bool:
         """Check if any constraint values are set."""
-        return any(v is not None for v in self.dict().values())
+        return any(v is not None for v in model_dump(self).values())
 
     @staticmethod
     def merge_constraints(a: ConstraintsBaseT | None, b: ConstraintsBaseT | None) -> ConstraintsBaseT | None:
         """Merge two constraint objects, with b taking precedence over a."""
         constraints_class = None
         if isinstance(a, ConstraintsBase):  # pragma: no cover
-            root_type_field_constraints = {k: v for k, v in a.dict(by_alias=True).items() if v is not None}
+            root_type_field_constraints = {k: v for k, v in model_dump(a, by_alias=True).items() if v is not None}
             constraints_class = a.__class__
         else:
             root_type_field_constraints = {}  # pragma: no cover
 
         if isinstance(b, ConstraintsBase):  # pragma: no cover
-            model_field_constraints = {k: v for k, v in b.dict(by_alias=True).items() if v is not None}
+            model_field_constraints = {k: v for k, v in model_dump(b, by_alias=True).items() if v is not None}
             constraints_class = constraints_class or b.__class__
         else:
             model_field_constraints = {}
 
         if constraints_class is None or not issubclass(constraints_class, ConstraintsBase):  # pragma: no cover
             return None
 
-        return constraints_class.parse_obj({
-            **root_type_field_constraints,
-            **model_field_constraints,
-        })
+        return model_validate(
+            constraints_class,
+            {
+                **root_type_field_constraints,
+                **model_field_constraints,
+            },
+        )
 
 
 class DataModelFieldBase(_BaseModel):
@@ -373,14 +376,14 @@ def fall_back_to_nullable(self) -> bool:
 
     def copy_deep(self) -> Self:
         """Create a deep copy of this field to avoid mutating the original."""
-        copied = self.copy()
+        copied = model_copy(self)
         copied.parent = None
         copied.extras = deepcopy(self.extras)
-        copied.data_type = self.data_type.copy()
+        copied.data_type = model_copy(self.data_type)
         if self.data_type.data_types:
-            copied.data_type.data_types = [dt.copy() for dt in self.data_type.data_types]
+            copied.data_type.data_types = [model_copy(dt) for dt in self.data_type.data_types]
         if self.data_type.dict_key:
-            copied.data_type.dict_key = self.data_type.dict_key.copy()
+            copied.data_type.dict_key = model_copy(self.data_type.dict_key)
         return copied
 
     def replace_data_type(self, new_data_type: DataType, *, clear_old_parent: bool = True) -> None:

src/datamodel_code_generator/model/msgspec.py

@@ -47,6 +47,7 @@
     _remove_none_from_union,
     chain_as_tuple,
 )
+from datamodel_code_generator.util import model_dump
 
 UNSET_TYPE = "UnsetType"
 
@@ -389,7 +390,7 @@ def _get_meta_string(self) -> str | None:
                 **data,
                 **{
                     k: self._get_strict_field_constraint_value(k, v)
-                    for k, v in self.constraints.dict().items()
+                    for k, v in model_dump(self.constraints).items()
                     if k in self._META_FIELD_KEYS
                 },
             }

src/datamodel_code_generator/model/pydantic/__init__.py

@@ -6,7 +6,7 @@
 
 from __future__ import annotations
 
-from typing import TYPE_CHECKING, Optional
+from typing import TYPE_CHECKING, Any, Optional
 
 from pydantic import BaseModel as _BaseModel
 
@@ -36,6 +36,16 @@ class Config(_BaseModel):
     orm_mode: Optional[bool] = None  # noqa: UP045
     validate_assignment: Optional[bool] = None  # noqa: UP045
 
+    def dict(  # type: ignore[override]
+        self, **kwargs: Any
+    ) -> dict[str, Any]:
+        """Version-compatible dict method for templates."""
+        from datamodel_code_generator.util import PYDANTIC_V2  # noqa: PLC0415
+
+        if PYDANTIC_V2:
+            return self.model_dump(**kwargs)
+        return super().dict(**kwargs)
+
 
 __all__ = [
     "BaseModel",

src/datamodel_code_generator/model/pydantic/base_model.py

@@ -25,6 +25,7 @@
     IMPORT_FIELD,
 )
 from datamodel_code_generator.types import STANDARD_LIST, UnionIntFloat, chain_as_tuple
+from datamodel_code_generator.util import model_dump, model_validate
 
 if TYPE_CHECKING:
     from collections import defaultdict
@@ -199,7 +200,7 @@ def __str__(self) -> str:  # noqa: PLR0912
                     if any(d.import_ == IMPORT_ANYURL for d in self.data_type.all_data_types)
                     else {
                         k: self._get_strict_field_constraint_value(k, v)
-                        for k, v in self.constraints.dict(exclude_unset=True).items()
+                        for k, v in model_dump(self.constraints, exclude_unset=True).items()
                     }
                 ),
             }
@@ -402,4 +403,4 @@ def __init__(  # noqa: PLR0912, PLR0913
         if config_parameters:
             from datamodel_code_generator.model.pydantic import Config  # noqa: PLC0415
 
-            self.extra_template_data["config"] = Config.parse_obj(config_parameters)  # pyright: ignore[reportArgumentType]
+            self.extra_template_data["config"] = model_validate(Config, config_parameters)  # pyright: ignore[reportArgumentType]