```

`Field` works the same way as `Query`, `Path` and `Body`, it has all the same parameters, etc.

!!! note "Technical Details"
    Actually, `Query`, `Path` and others you'll see next create objects of subclasses of a common `Param` class, which is itself a subclass of Pydantic's `FieldInfo` class.

    And Pydantic's `Field` returns an instance of `FieldInfo` as well.

    バックグラウンドタスク (後述) がある場合は、それらは全てのミドルウェアの *後に* 実行されます。

## ミドルウェアの作成

ミドルウェアを作成するには、関数の上部でデコレータ `@app.middleware("http")` を使用します。

ミドルウェア関数は以下を受け取ります:

* `request`。
* パラメータとして `request` を受け取る関数 `call_next`。
    * この関数は、対応する*path operation*に `request` を渡します。
    * 次に、対応する*path operation*によって生成された `response` を返します。
* その後、`response` を返す前にさらに `response` を変更することもできます。

```Python hl_lines="8-9  11  14"

@app.get("/redoc", include_in_schema=False)
async def redoc_html():
    return get_redoc_html(
        openapi_url=app.openapi_url,
        title=app.title + " - ReDoc",
        redoc_js_url="https://unpkg.com/redoc@next/bundles/redoc.standalone.js",
    )


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

# Run a Server Manually

## Use the `fastapi run` Command

In short, use `fastapi run` to serve your FastAPI application:

<div class="termy">

```console
$ <font color="#4E9A06">fastapi</font> run <u style="text-decoration-style:single">main.py</u>
<font color="#3465A4">INFO    </font> Using path <font color="#3465A4">main.py</font>

We are already halfway there.

We just need to add a *path operation* for the user/client to actually send the `username` and `password`.

You can use the same type declarations with `str`, `float`, `bool` and many other complex data types.

Several of these are explored in the next chapters of the tutorial.

## Order matters

When creating *path operations*, you can find situations where you have a fixed path.

Like `/users/me`, let's say that it's to get data about the current user.

    만약 (나중에 문서에서 다룰) 백그라운드 작업이 있다면, 모든 미들웨어가 실행되고 *난 후에* 실행됩니다.

## 미들웨어 만들기

미들웨어를 작성하기 위해서 함수 상단에 `@app.middleware("http")` 데코레이터를 사용할 수 있습니다.

미들웨어 함수는 다음 항목들을 받습니다:

* `request`.
* `request`를 매개변수로 받는 `call_next` 함수.
    * 이 함수는 `request`를 해당하는 *경로 작업*으로 전달합니다.
    * 그런 다음, *경로 작업*에 의해 생성된 `response` 를 반환합니다.
* `response`를 반환하기 전에 추가로 `response`를 수정할 수 있습니다.

```Python hl_lines="8-9  11  14"

That way, the same route class can handle gzip compressed or uncompressed requests.

```Python hl_lines="8-15"
{!../../../docs_src/custom_request_and_route/tutorial001.py!}
```

### Create a custom `GzipRoute` class

Next, we create a custom subclass of `fastapi.routing.APIRoute` that will make use of the `GzipRequest`.

This time, it will overwrite the method `APIRoute.get_route_handler()`.

    price: float
    tags: List[str] = field(default_factory=list)
    description: Union[str, None] = None
    tax: Union[float, None] = None


app = FastAPI()


@app.get("/items/next", response_model=Item)
async def read_next_item():
    return {
        "name": "Island In The Moon",
        "price": 12.99,
        "description": "A place to be be playin' and havin' fun",
        "tags": ["breater"],

models.Base.metadata.create_all(bind=engine)

app = FastAPI()


@app.middleware("http")
async def db_session_middleware(request: Request, call_next):
    response = Response("Internal server error", status_code=500)
    try:
        request.state.db = SessionLocal()
        response = await call_next(request)
    finally:
        request.state.db.close()
    return response


# Dependency
def get_db(request: Request):