from typing import Union

from fastapi import FastAPI, Header
from typing_extensions import Annotated

app = FastAPI()


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

Sie wird direkt in FastAPI importiert/inkludiert, sodass Sie sie von `fastapi` importieren können und vermeiden, versehentlich das alternative `BackgroundTask` (ohne das `s` am Ende) von `starlette.background` zu importieren.

from fastapi import FastAPI, Query

app = FastAPI()


@app.get("/items/")
async def read_items(q: str | None = Query(default=..., min_length=3)):
    results = {"items": [{"item_id": "Foo"}, {"item_id": "Bar"}]}
    if q:
        results.update({"q": q})

De todos modos, en cualquiera de los casos anteriores, FastAPI seguirá funcionando de forma asíncrona y será extremadamente rápido.

Pero siguiendo los pasos anteriores, FastAPI podrá hacer algunas optimizaciones de rendimiento.

## Detalles Técnicos

from typing import List, Union

from fastapi import FastAPI, Query
from typing_extensions import Annotated

app = FastAPI()


@app.get("/items/")
async def read_items(q: Annotated[Union[List[str], None], Query()] = None):
    query_items = {"q": q}

from typing import Union

from fastapi import FastAPI, Path
from pydantic import BaseModel
from typing_extensions import Annotated

app = FastAPI()


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


@app.put("/items/{item_id}")
async def update_item(
    item_id: Annotated[int, Path(title="The ID of the item to get", ge=0, le=1000)],

from typing import List

from fastapi import FastAPI
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: str
    price: float


class ResponseMessage(BaseModel):
    message: str


class User(BaseModel):
    username: str
    email: str


@app.post("/items/", response_model=ResponseMessage, tags=["items"])
async def create_item(item: Item):

你可以配置一些额外的 <a href="https://swagger.io/docs/open-source-tools/swagger-ui/usage/configuration/" class="external-link" target="_blank">Swagger UI 参数</a>.

如果需要配置它们，可以在创建 `FastAPI()` 应用对象时或调用 `get_swagger_ui_html()` 函数时传递 `swagger_ui_parameters` 参数。

`swagger_ui_parameters` 接受一个直接传递给 Swagger UI的字典，包含配置参数键值对。

FastAPI会将这些配置转换为 **JSON**，使其与 JavaScript 兼容，因为这是 Swagger UI 需要的。

## 不使用语法高亮

比如，你可以禁用 Swagger UI 中的语法高亮。

当没有改变设置时，语法高亮默认启用：

from typing import Annotated

from fastapi import FastAPI, Query

app = FastAPI()


@app.get("/items/")
async def read_items(q: Annotated[str, Query(min_length=3)] = ...):
    results = {"items": [{"item_id": "Foo"}, {"item_id": "Bar"}]}
    if q:
        results.update({"q": q})

from fastapi import FastAPI, Form
from pydantic import BaseModel
from typing_extensions import Annotated

app = FastAPI()


class FormData(BaseModel):
    username: str
    password: str
    model_config = {"extra": "forbid"}


@app.post("/login/")
async def login(data: Annotated[FormData, Form()]):