Pydantic Undefined Annotation: name 'Optional' is not defined

[bonk1t]

Describe the bug

An import statement is missing in the generated model code: you need to ensure that List, Optional, etc are imported from typing. datamodel-code-generator==0.28.3

self = <pydantic._internal._generate_schema.GenerateSchema object at 0x10e7431f0>, name = 'parameters', field_info = FieldInfo(annotation=ForwardRef('Optional[Parameters]'), required=False, default=None)
decorators = DecoratorInfos(validators={}, field_validators={}, root_validators={}, field_serializers={}, model_serializers={}, model_validators={}, computed_fields={})

    def _common_field_schema(  # C901
        self, name: str, field_info: FieldInfo, decorators: DecoratorInfos
    ) -> _CommonField:
        # Update FieldInfo annotation if appropriate:
        FieldInfo = import_cached_field_info()
        if not field_info.evaluated:
            # TODO Can we use field_info.apply_typevars_map here?
            try:
                evaluated_type = _typing_extra.eval_type(field_info.annotation, *self._types_namespace)
            except NameError as e:
>               raise PydanticUndefinedAnnotation.from_name_error(e) from e
E               pydantic.errors.PydanticUndefinedAnnotation: name 'Optional' is not defined
E               
E               For further information visit https://errors.pydantic.dev/2.10/u/undefined-annotation

../.venv/lib/python3.10/site-packages/pydantic/_internal/_generate_schema.py:1227: PydanticUndefinedAnnotation

To Reproduce

Example schema:

{
  "openapi": "3.1.0",
  "info": {
    "title": "Get Headers",
    "description": "Get headers endpoint",
    "version": "v1.0.0"
  },
  "servers": [
    {
      "url": "https://{domain}-gntxktyfsq-uc.a.run.app/"
    }
  ],
  "paths": {
    "/": {
      "get": {
        "description": "This is a test function to return all request headers.",
        "operationId": "PrintHeaders",
        "parameters": [
            {
                "name": "query",
                "in": "query",
                "description": "Query test parameter. Should be 'test'",
                "required": true,
                "schema": {
                    "type": "string"
                },
                "example": "test"
            },
            {
                "name": "domain",
                "in": "path",
                "description": "Domain parameter. Should be 'print-headers'",
                "required": true,
                "schema": {
                    "type": "string"
                },
                "example": "print-headers"
            }
        ],
        "requestBody": {},
        "deprecated": false,
        "security": [
          {
            "apiKey": []
          }
        ]
      }
    }
  },
  "components": {
    "schemas": {
      "RunReportParams": {
        "properties": {},
        "type": "object",
        "required": []
      }
    },
    "securitySchemes": {
      "apiKey": {
        "type": "apiKey"
      }
    }
  }
}

To reproduce, run tests:

python -m pip install --upgrade pip
pip install -r requirements-dev.txt
pytest -v -k test_tool_factory

Expected behavior Correctly generated model (it worked before - comparison: https://github.com/VRSEN/agency-swarm/compare/main...bonk1t:agency-swarm:fix/observability-and-tests?expand=1).

Version:

• OS: MacOS 15.3.1
• Python version: Python 3.10.
• datamodel-code-generator version: the latest: 0.28.3.

Code that triggers the error: https://github.com/bonk1t/agency-swarm/blob/389bda387eb0e887073c7e1049c16d7c43791433/agency_swarm/tools/ToolFactory.py#L71

[bonk1t]

A workaround I used: https://github.com/VRSEN/agency-swarm/pull/264/commits/676757c0b95de83828eb1724863464132c4ff58e#diff-6b73d00cdda2ecc6b5b9c34d924f7262e20553ccfefa7b1b5a17314d797be543R107-R150