),
    ]


class HTTPBase(SecurityBase):
    def __init__(
        self,
        *,
        scheme: str,
        scheme_name: Optional[str] = None,
        description: Optional[str] = None,
        auto_error: bool = True,
    ):
        self.model = HTTPBaseModel(scheme=scheme, description=description)
        self.scheme_name = scheme_name or self.__class__.__name__
        self.auto_error = auto_error

from typing import Union

from fastapi import FastAPI
from pydantic import BaseModel, EmailStr

app = FastAPI()


class BaseUser(BaseModel):
    username: str
    email: EmailStr
    full_name: Union[str, None] = None


class UserIn(BaseUser):
    password: str


@app.post("/user/")
async def create_user(user: UserIn) -> BaseUser:

from typing import Union

from fastapi import FastAPI
from pydantic import BaseModel, EmailStr

app = FastAPI()


class UserIn(BaseModel):
    username: str
    password: str
    email: EmailStr
    full_name: Union[str, None] = None


# Don't do this in production!
@app.post("/user/")
async def create_user(user: UserIn) -> UserIn:

from fastapi.encoders import jsonable_encoder
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: Union[str, None] = None
    description: Union[str, None] = None
    price: Union[float, None] = None
    tax: float = 10.5
    tags: list[str] = []


items = {
    "foo": {"name": "Foo", "price": 50.2},
    "bar": {"name": "Bar", "description": "The bartenders", "price": 62, "tax": 20.2},

from typing import Set, Union

from fastapi import FastAPI
from pydantic import BaseModel

app = FastAPI()


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


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

     *
     * @see jcifs.SmbResourceLocator#getParent()
     */
    @Override
    public String getParent () {
        String str = this.url.getAuthority();

        if ( str != null && !str.isEmpty() ) {
            StringBuffer sb = new StringBuffer("smb://");

            sb.append(str);

            String urlpath = getURLPath();
            if ( urlpath.length() > 1 ) {
                sb.append(urlpath);

{!../../../docs_src/python_types/tutorial009.py!}
```

Using `Optional[str]` instead of just `str` will let the editor help you detecting errors where you could be assuming that a value is always a `str`, when it could actually be `None` too.

`Optional[Something]` is actually a shortcut for `Union[Something, None]`, they are equivalent.

This also means that in Python 3.10, you can use `Something | None`:

=== "Python 3.10+"

                }
                System.arraycopy( str.getBytes( UNI_ENCODING ), 0,
                                    dst, dstIndex, str.length() * 2 );
                dstIndex += str.length() * 2;
                dst[dstIndex++] = (byte)'\0';
                dst[dstIndex++] = (byte)'\0';
            } else {
                byte[] b = str.getBytes( OEM_ENCODING );

from fastapi.params import Body, Cookie, Depends, Header, Param, Path, Query

test_data: List[Any] = ["teststr", None, ..., 1, []]


def get_user():
    return {}  # pragma: no cover


def test_param_repr_str():
    assert repr(Param("teststr")) == "Param(teststr)"


def test_param_repr_none():
    assert repr(Param(None)) == "Param(None)"


def test_param_repr_ellipsis():
    assert repr(Param(...)) == IsOneOf(

app = FastAPI()


class UserIn(BaseModel):
    username: str
    password: str
    email: EmailStr
    full_name: Union[str, None] = None


class UserOut(BaseModel):
    username: str
    email: EmailStr
    full_name: Union[str, None] = None


class UserInDB(BaseModel):
    username: str
    hashed_password: str
    email: EmailStr
    full_name: Union[str, None] = None