informa ao SQLModel que o `id` é a **chave primária** no banco de dados SQL (você pode aprender mais sobre chaves primárias SQL na documentação do SQLModel).

    **Nota:** Usamos `int | None` para o campo de chave primária para que, no código Python, possamos *criar um objeto sem um `id`* (`id=None`), assumindo que o banco de dados irá *gerá-lo ao salvar*. O SQLModel entende que o banco de dados fornecerá o `id` e *define a coluna como um `INTEGER` não nulo* no esquema do banco de dados. Veja...

from typing import Union

from fastapi import FastAPI
from pydantic import BaseModel, EmailStr

app = FastAPI()


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


class UserIn(UserBase):
    password: str


class UserOut(UserBase):
    pass


class UserInDB(UserBase):
    hashed_password: str


def fake_password_hasher(raw_password: str):

from fastapi import FastAPI
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: str
    description: str | None = None
    price: float
    tax: float = 10.5


items = {
    "foo": {"name": "Foo", "price": 50.2},
    "bar": {"name": "Bar", "description": "The Bar fighters", "price": 62, "tax": 20.2},
    "baz": {
        "name": "Baz",
        "description": "There goes my baz",

from typing import Optional

from fastapi import FastAPI, File
from fastapi.testclient import TestClient

app = FastAPI()


@app.post("/files")
async def upload_files(files: Optional[list[bytes]] = File(None)):
    if files is None:
        return {"files_count": 0}
    return {"files_count": len(files), "sizes": [len(f) for f in files]}


def test_optional_bytes_list():
    client = TestClient(app)
    response = client.post(

from typing import Union

from fastapi import FastAPI
from pydantic import BaseModel

app = FastAPI()


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


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

    font-size: 10pt;
    color: #000000;
    text-decoration: none
}
a.plain {
    display: inline;
    float: none;
    width: auto;
    height: auto
}
a.sort {
    display: block;
    float: left;
    width: 100px;
    height: 15px;
    font-family: Verdana, sans-serif;
    font-size: 8pt;
    font-weight: bold;
    text-decoration: none;
    color: #000000;
    background-color: #d0d0d0;

## Paramètres optionnels

De la même façon, vous pouvez définir des paramètres de requête comme optionnels, en leur donnant comme valeur par défaut `None` :

{* ../../docs_src/query_params/tutorial002.py hl[9] *}

Ici, le paramètre `q` sera optionnel, et aura `None` comme valeur par défaut.

/// check | Remarque

// along with this program.  If not, see <http://www.gnu.org/licenses/>.

package csv

import (
	"encoding/xml"
	"errors"
	"fmt"
	"io"
	"strings"
	"unicode/utf8"
)

const (
	none   = "none"
	use    = "use"
	ignore = "ignore"

	defaultRecordDelimiter      = "\n"
	defaultFieldDelimiter       = ","
	defaultQuoteCharacter       = `"`
	defaultQuoteEscapeCharacter = `"`

def test_union_body_discriminator_assignment(client: TestClient) -> None:
    response = client.post("/pet/assignment", json={"pet_type": "cat", "meows": 5})
    assert response.status_code == 200, response.text
    assert response.json() == {"pet_type": "cat", "meows": 5}


def test_union_body_discriminator_annotated(client: TestClient) -> None:
    response = client.post("/pet/annotated", json={"pet_type": "dog", "barks": 3.5})

    client = TestClient(mod.app)
    return client


@pytest.mark.parametrize(
    "path,headers,expected_status,expected_response",
    [
        ("/items", None, 200, {"X-Token values": None}),
        ("/items", {"x-token": "foo"}, 200, {"X-Token values": ["foo"]}),
        (
            "/items",
            [("x-token", "foo"), ("x-token", "bar")],
            200,