If something seems interesting and useful to your project, go ahead and check it, but otherwise, you might probably just skip them.

/// tip

If you want to **learn FastAPI** in a structured way (recommended), go and read the [Tutorial - User Guide](../tutorial/index.md) chapter by chapter instead.

`str`을 상속함으로써 API 문서는 값이 `string` 형이어야 하는 것을 알게 되고 이는 문서에 제대로 표시됩니다.

가능한 값들에 해당하는 고정된 값의 클래스 어트리뷰트들을 만듭니다:

{* ../../docs_src/path_params/tutorial005_py310.py hl[1,6:9] *}

/// tip | 팁

혹시 궁금하다면, "AlexNet", "ResNet", 그리고 "LeNet"은 그저 머신 러닝 <dfn title="기술적으로는 딥 러닝 모델 아키텍처">모델</dfn>들의 이름입니다.

///

### *경로 매개변수* 선언 { #declare-a-path-parameter }

`Invoice` ボディを受け取り、クエリパラメータ `callback_url` にコールバック用の URL を含める *path operation* を持ちます。

この部分はとても普通で、ほとんどのコードはすでに見覚えがあるはずです:

{* ../../docs_src/openapi_callbacks/tutorial001_py310.py hl[7:11,34:51] *}

/// tip | 豆知識

`callback_url` クエリパラメータは、Pydantic の [Url](https://docs.pydantic.dev/latest/api/networks/) 型を使用します。

///

唯一の新しい点は、*path operation デコレータ*の引数として `callbacks=invoices_callback_router.routes` を渡すことです。これが何かは次で見ます。

例如，你可以建立 `HTTPBearer` 的子類別，讓它回傳 `403 Forbidden` 錯誤，而不是預設的 `401 Unauthorized` 錯誤：

{* ../../docs_src/authentication_error_status_code/tutorial001_an_py310.py hl[9:13] *}

/// tip
注意這個函式回傳的是例外物件本身，而不是直接拋出它。拋出的動作會在其餘的內部程式碼中處理。

data: {"name": "Plumbus", "price": 32.99}

```

SSE is commonly used for AI chat streaming, live notifications, logs and observability, and other cases where the server pushes updates to the client.

/// tip

If you want to stream binary data, for example video or audio, check the advanced guide: [Stream Data](../advanced/stream-data.md).

///

## Stream SSE with FastAPI { #stream-sse-with-fastapi }

///

## Use Cases { #use-cases }

You could use this to stream data from an **AI LLM** service, from **logs** or **telemetry**, or from other types of data that can be structured in **JSON** items.

/// tip

If you want to stream binary data, for example video or audio, check the advanced guide: [Stream Data](../advanced/stream-data.md).

///

## Stream JSON Lines with FastAPI { #stream-json-lines-with-fastapi }

Then create class attributes with fixed values, which will be the available valid values:

{* ../../docs_src/path_params/tutorial005_py310.py hl[1,6:9] *}

/// tip

If you are wondering, "AlexNet", "ResNet", and "LeNet" are just names of Machine Learning <dfn title="Technically, Deep Learning model architectures">models</dfn>.

///

    * Then it returns the `response` generated by the corresponding *path operation*.
* You can then further modify the `response` before returning it.

{* ../../docs_src/middleware/tutorial001_py310.py hl[8:9,11,14] *}

/// tip

Keep in mind that custom proprietary headers can be added [using the `X-` prefix](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers).

* /// info: /// info | Informação
* /// note | Technical Details: /// note | Detalhes Técnicos
* /// info | Very Technical Details: /// note | Detalhes Técnicos Avançados
* /// note: /// note | Nota
* /// tip: /// tip | Dica
* /// warning: /// warning | Atenção
* you should: você deveria
* async context manager: gerenciador de contexto assíncrono
* autocomplete: autocompletar
* autocompletion: preenchimento automático

            // More stuff here
    }
}
```

/// tip

Notice the auto-generated server with a `url` value of `/api/v1`, taken from the `root_path`.

///

In the docs UI at [http://127.0.0.1:9999/api/v1/docs](http://127.0.0.1:9999/api/v1/docs) it would look like:

<img src="/img/tutorial/behind-a-proxy/image03.png">

/// tip

The docs UI will interact with the server that you select.

///