from typing import List, Union

from fastapi import FastAPI, Header
from typing_extensions import Annotated

app = FastAPI()


@app.get("/items/")
async def read_items(x_token: Annotated[Union[List[str], None], Header()] = None):

from fastapi import FastAPI

app = FastAPI()


@app.get("/items/{item_id}")
async def read_user_item(
    item_id: str, needy: str, skip: int = 0, limit: int | None = None
):
    item = {"item_id": item_id, "needy": needy, "skip": skip, "limit": limit}

app = FastAPI()


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


@app.get("/")
def read_root():
    return {"Hello": "World"}


@app.get("/items/{item_id}")
def read_item(item_id: int, q: Union[str, None] = None):
    return {"item_id": item_id, "q": q}


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

from fastapi import FastAPI
from fastapi.encoders import jsonable_encoder
from pydantic import BaseModel

fake_db = {}


class Item(BaseModel):
    title: str
    timestamp: datetime
    description: str | None = None


app = FastAPI()


@app.put("/items/{id}")
def update_item(id: str, item: Item):
    json_compatible_item_data = jsonable_encoder(item)

</div>

Das bedeutet, dass es **immer einen Wert** hat, der Wert kann jedoch manchmal `None` sein (oder `null` in JSON).

Das bedeutet, dass Clients, die Ihre API verwenden, nicht prüfen müssen, ob der Wert vorhanden ist oder nicht. Sie können davon ausgehen, dass das Feld immer vorhanden ist. In einigen Fällen hat es jedoch nur den Defaultwert `None`.

from fastapi import FastAPI, Query
from typing_extensions import Annotated

app = FastAPI()


@app.get("/items/")
async def read_items(
    q: Annotated[
        Union[str, None], Query(min_length=3, max_length=50, pattern="^fixedquery$")
    ] = None,
):
    results = {"items": [{"item_id": "Foo"}, {"item_id": "Bar"}]}
    if q:
        results.update({"q": q})

from fastapi import FastAPI
from pydantic import BaseModel, EmailStr

app = FastAPI()


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


class UserIn(BaseUser):
    password: str


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

		}
		if ip == "" {
			// fallback to None when a service does not have a VIP
			ip = "None"
		}
		serviceNames[ip] = s.Hostname
	}
	for _, s := range d.Workloads {
		var ip string
		if len(s.WorkloadIPs) != 0 {
			ip = s.WorkloadIPs[0]
		}
		if ip == "" {
			// fallback to None when a workload does not have an IP
			ip = "None"
		}
		workloadNames[ip] = s.Name + "." + s.Namespace
	}

  public void testOf() {
    assertMapEquals(ImmutableMap.of("one", 1), "one", 1);
    assertMapEquals(ImmutableMap.of("one", 1, "two", 2), "one", 1, "two", 2);
    assertMapEquals(
        ImmutableMap.of("one", 1, "two", 2, "three", 3), "one", 1, "two", 2, "three", 3);
    assertMapEquals(
        ImmutableMap.of("one", 1, "two", 2, "three", 3, "four", 4),
        "one",
        1,
        "two",
        2,
        "three",

        "name": "Baz",
        "description": None,
        "price": 50.2,
        "tax": 10.5,
        "tags": [],
    }


def test_put(client: TestClient):
    response = client.put(
        "/items/bar", json={"name": "Barz", "price": 3, "description": None}
    )
    assert response.json() == {
        "name": "Barz",
        "description": None,
        "price": 3,
        "tax": 10.5,