@dataclass
class Dependant:
    path_params: list[ModelField] = field(default_factory=list)
    query_params: list[ModelField] = field(default_factory=list)
    header_params: list[ModelField] = field(default_factory=list)
    cookie_params: list[ModelField] = field(default_factory=list)
    body_params: list[ModelField] = field(default_factory=list)
    dependencies: list["Dependant"] = field(default_factory=list)
    name: str | None = None

            )
        self.example = example
        self.include_in_schema = include_in_schema
        self.openapi_examples = openapi_examples
        kwargs = dict(
            default=default,
            default_factory=default_factory,
            alias=alias,
            title=title,
            description=description,
            gt=gt,
            ge=ge,
            lt=lt,
            le=le,
            min_length=min_length,

        item_id: Annotated[int, Path(title="The ID of the item to get")],
    ):
        return {"item_id": item_id}
    ```
    """
    return params.Path(
        default=default,
        default_factory=default_factory,
        alias=alias,
        alias_priority=alias_priority,
        validation_alias=validation_alias,
        serialization_alias=serialization_alias,
        title=title,

}

static TracingContext* CreateTracingExecutionContext(const char* fn_name,
                                                     TF_Status* s) {
  if (default_factory) {
    return default_factory(fn_name, s);
  }
  tsl::Set_TF_Status_from_Status(
      s, errors::FailedPrecondition("default_factory is nullptr"));
  return nullptr;
}

}  // end namespace tracing
}  // end namespace tensorflow

from dataclasses import dataclass, field

from fastapi import FastAPI


@dataclass
class Item:
    name: str
    price: float
    tags: list[str] = field(default_factory=list)
    description: str | None = None
    tax: float | None = None


app = FastAPI()


@app.get("/items/next", response_model=Item)
async def read_next_item():
    return {
        "name": "Island In The Moon",
        "price": 12.99,

from pydantic.dataclasses import dataclass  # (2)


@dataclass
class Item:
    name: str
    description: str | None = None


@dataclass
class Author:
    name: str
    items: list[Item] = field(default_factory=list)  # (3)


app = FastAPI()


@app.post("/authors/{author_id}/items/", response_model=Author)  # (4)
async def create_author_items(author_id: str, items: list[Item]):  # (5)

from fastapi.testclient import TestClient
from inline_snapshot import snapshot


@dataclass
class Item:
    id: uuid.UUID
    name: str
    price: float
    tags: list[str] = field(default_factory=list)
    description: str | None = None
    tax: float | None = None


app = FastAPI()


@app.get("/item", response_model=Item)
async def read_item():
    return {
        "id": uuid.uuid4(),

        self.update_with_validations(json_schema, schema, self.ValidationsMapping.bytes)
        return json_schema


# TODO: remove when dropping support for Pydantic < v2.12.3
_Attrs = {
    "default": ...,
    "default_factory": None,
    "alias": None,
    "alias_priority": None,
    "validation_alias": None,
    "serialization_alias": None,
    "title": None,
    "field_title_generator": None,
    "description": None,

from fastapi import FastAPI
from fastapi.testclient import TestClient
from pydantic import BaseModel, Field

app = FastAPI()


class ResponseModel(BaseModel):
    code: int = 200
    message: str = Field(default_factory=lambda: "Successful operation.")


@app.get(
    "/response_model_has_default_factory_return_dict",
    response_model=ResponseModel,
)
async def response_model_has_default_factory_return_dict():

* ✨ Add OpenAPI `external_docs` parameter to `FastAPI`. PR [#13713](https://github.com/fastapi/fastapi/pull/13713) by [@cmtoro](https://github.com/cmtoro).

### Fixes

* ⚡️ Fix `default_factory` for response model field with Pydantic V1. PR [#9704](https://github.com/fastapi/fastapi/pull/9704) by [@vvanglro](https://github.com/vvanglro).