from fastapi import FastAPI, Header
from pydantic import BaseModel

app = FastAPI()


class CommonHeaders(BaseModel):
    host: str
    save_data: bool
    if_modified_since: Union[str, None] = None
    traceparent: Union[str, None] = None
    x_tag: list[str] = []


@app.get("/items/")
async def read_items(headers: CommonHeaders = Header()):

from typing import Union

from fastapi import FastAPI
from pydantic import BaseModel


class Item(BaseModel):
    name: str
    description: Union[str, None] = None
    price: float
    tax: Union[float, None] = None


app = FastAPI()


@app.post("/items/")
async def create_item(item: Item):

def get_swagger_ui_html(
    *,
    openapi_url: Annotated[
        str,
        Doc(
            """
            The OpenAPI URL that Swagger UI should load and use.

            This is normally done automatically by FastAPI using the default URL
            `/openapi.json`.
            """
        ),
    ],
    title: Annotated[
        str,
        Doc(
            """

app = FastAPI()


def query_extractor(q: Union[str, None] = None):
    return q


def query_or_cookie_extractor(
    q: str = Depends(query_extractor),
    last_query: Union[str, None] = Cookie(default=None),
):
    if not q:
        return last_query
    return q


@app.get("/items/")
async def read_query(query_or_default: str = Depends(query_or_cookie_extractor)):

    * Em requisições e respostas será representado como uma `str`.
* `datetime.datetime`:
    * O `datetime.datetime` do Python.
    * Em requisições e respostas será representado como uma `str` no formato ISO 8601, exemplo: `2008-09-15T15:53:00+05:00`.
* `datetime.date`:
    * O `datetime.date` do Python.
    * Em requisições e respostas será representado como uma `str` no formato ISO 8601, exemplo: `2008-09-15`.
* `datetime.time`:

    class PersonBase(BaseModel):
        name: str
        lastname: str

    class Person(PersonBase):
        @property
        def full_name(self) -> str:
            return f"{self.name} {self.lastname}"

        model_config = ConfigDict(from_attributes=True)

    class PersonCreate(PersonBase):
        pass

    class PersonRead(PersonBase):
        full_name: str

        model_config = {"from_attributes": True}

    b: Annotated[float, Body(allow_inf_nan=False)] = 0,
) -> str:
    return "OK"


client = TestClient(app)


@pytest.mark.parametrize(
    "value,code",
    [
        ("-1", 200),
        ("inf", 200),
        ("-inf", 200),
        ("nan", 200),
        ("0", 200),
        ("342", 200),
    ],
)
def test_allow_inf_nan_param_true(value: str, code: int):
    response = client.post(f"/?x={value}")

from pydantic import BaseModel, HttpUrl

app = FastAPI()


class Image(BaseModel):
    url: HttpUrl
    name: str


class Item(BaseModel):
    name: str
    description: Union[str, None] = None
    price: float
    tax: Union[float, None] = None
    tags: set[str] = set()
    images: Union[list[Image], None] = None


@app.put("/items/{item_id}")
async def update_item(item_id: int, item: Item):

from fastapi import FastAPI, Header
from pydantic import BaseModel

app = FastAPI()


class CommonHeaders(BaseModel):
    host: str
    save_data: bool
    if_modified_since: str | None = None
    traceparent: str | None = None
    x_tag: list[str] = []


@app.get("/items/")
async def read_items(headers: CommonHeaders = Header()):

```Python hl_lines="1  4"
{!../../docs_src/python_types/tutorial009_py39.py!}
```

Использование `Optional[str]` вместо просто `str` позволит редактору кода помочь вам обнаружить ошибки, когда вы предполагаете, что значение всегда `str`, хотя на самом деле оно может быть и `None`.

`Optional[Something]` — это на самом деле сокращение для `Union[Something, None]`, они эквивалентны.