"default": ...,
    "default_factory": None,
    "alias": None,
    "alias_priority": None,
    "validation_alias": None,
    "serialization_alias": None,
    "title": None,
    "field_title_generator": None,
    "description": None,
    "examples": None,
    "exclude": None,
    "exclude_if": None,
    "discriminator": None,
    "deprecated": None,
    "json_schema_extra": None,
    "frozen": None,

app = FastAPI()


class UserIn(BaseModel):
    username: str
    password: str
    email: EmailStr
    full_name: str | None = None


class UserOut(BaseModel):
    username: str
    email: EmailStr
    full_name: str | None = None


@app.post("/user/", response_model=UserOut)
async def create_user(user: UserIn) -> Any:

```Python
say_hi(name=None)  # Das funktioniert, None ist gültig 🎉
```

Die gute Nachricht ist: In den meisten Fällen können Sie einfach `|` verwenden, um Unions von Typen zu definieren:

```python
def say_hi(name: str | None):
    print(f"Hey {name}!")
```

class User(BaseModel):
    username: str


def get_current_user(oauth_header: str | None = Security(api_key)):
    if oauth_header is None:
        return None
    user = User(username=oauth_header)
    return user


@app.get("/users/me")
def read_current_user(current_user: User | None = Depends(get_current_user)):
    if current_user is None:
        return {"msg": "Create an account first"}
    return current_user

# Without aliases


@app.get("/optional-str")
async def read_optional_str(p: Annotated[str | None, Cookie()] = None):
    return {"p": p}


class CookieModelOptionalStr(BaseModel):
    p: str | None = None


@app.get("/model-optional-str")
async def read_model_optional_str(p: Annotated[CookieModelOptionalStr, Cookie()]):
    return {"p": p.p}

from fastapi import FastAPI
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: str
    description: str | None = None
    price: float
    tax: float | None = None
    tags: set[str] = set()


@app.post(
    "/items/",
    summary="Create an item",
    description="Create an item with all the information, name, description, price, tax and a set of unique tags",
)

from pydantic import BaseModel, Field

app = FastAPI()


class Item(BaseModel):
    name: str = Field(examples=["Foo"])
    description: str | None = Field(default=None, examples=["A very nice Item"])
    price: float = Field(examples=[35.4])
    tax: float | None = Field(default=None, examples=[3.2])


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

```Python
say_hi(name=None)  # Ceci fonctionne, None est valide 🎉
```

La bonne nouvelle, c'est que, dans la plupart des cas, vous pourrez simplement utiliser `|` pour définir des unions de types :

```python
def say_hi(name: str | None):
    print(f"Hey {name}!")
```

            "price": 50.5,
            "description": None,
            "tax": None,
        },
        "user": {"username": "Dave", "full_name": None},
    }


def test_put_missing_body(client: TestClient):
    response = client.put("/items/5")
    assert response.status_code == 422
    assert response.json() == {
        "detail": [
            {
                "input": None,
                "loc": [

Пришло время использовать его с FastAPI. 🚀

У нас была такая аннотация типа:

```Python
q: str | None = None
```

Мы «обернём» это в `Annotated`, и получится:

```Python
q: Annotated[str | None] = None
```

Обе версии означают одно и то же: `q` — параметр, который может быть `str` или `None`, и по умолчанию равен `None`.

А теперь к самому интересному. 🎉