///

### `Response`

其他全部的响应都继承自主类 `Response`。

你可以直接返回它。

`Response` 类接受如下参数：

* `content` - 一个 `str` 或者 `bytes`。
* `status_code` - 一个 `int` 类型的 HTTP 状态码。
* `headers` - 一个由字符串组成的 `dict`。
* `media_type` - 一个给出媒体类型的 `str`，比如 `"text/html"`。

FastAPI（实际上是 Starlette）将自动包含 Content-Length 的头。它还将包含一个基于 media_type 的 Content-Type 头，并为文本类型附加一个字符集。

from fastapi import FastAPI

app = FastAPI(swagger_ui_parameters={"syntaxHighlight": False})


@app.get("/users/{username}")
async def read_user(username: str):

from fastapi import APIRouter, Body

router = APIRouter()


@router.post("/compute")
def compute(a: int = Body(), b: str = Body()):

from typing import Optional


def say_hi(name: Optional[str] = None):
    if name is not None:
        print(f"Hey {name}!")
    else:

from typing import Annotated

from fastapi import FastAPI, Path

app = FastAPI()


@app.get("/items/{item_id}")
async def read_items(
    q: str, item_id: Annotated[int, Path(title="The ID of the item to get")]
):
    results = {"item_id": item_id}
    if q:
        results.update({"q": q})

from typing import Annotated

from fastapi import FastAPI, Path

app = FastAPI()


@app.get("/items/{item_id}")
async def read_items(
    item_id: Annotated[int, Path(title="The ID of the item to get")], q: str
):
    results = {"item_id": item_id}
    if q:
        results.update({"q": q})

from typing import Annotated

from fastapi import FastAPI, Query

app = FastAPI()


@app.get("/items/")
async def read_items(
    q: Annotated[
        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, Header

app = FastAPI()


@app.get("/items/")
async def read_items(
    strange_header: str | None = Header(default=None, convert_underscores=False),
):

from typing import Union


def say_hi(name: Union[str, None] = None):
    if name is not None:
        print(f"Hey {name}!")
    else:

app = FastAPI()


class FilterParams(BaseModel):
    limit: int = Field(100, gt=0, le=100)
    offset: int = Field(0, ge=0)
    order_by: Literal["created_at", "updated_at"] = "created_at"
    tags: list[str] = []


@app.get("/items/")
async def read_items(filter_query: FilterParams = Query()):