# `FastAPI` class

Here's the reference information for the `FastAPI` class, with all its parameters, attributes and methods.

You can import the `FastAPI` class directly from `fastapi`:

```python
from fastapi import FastAPI
```

::: fastapi.FastAPI
    options:
        members:
            - openapi_version
            - webhooks
            - state
            - dependency_overrides
            - openapi

{!../../../docs_src/websockets/tutorial001.py!}
```

!!! note "Technical Details"
    You could also use `from starlette.websockets import WebSocket`.

    **FastAPI** provides the same `WebSocket` directly just as a convenience for you, the developer. But it comes directly from Starlette.

## Await for messages and send messages

In your WebSocket route you can `await` for messages and send messages.

```Python hl_lines="48-52"

## Eine `Response` direkt zurückgeben

Sie können auch Header hinzufügen, wenn Sie eine `Response` direkt zurückgeben.

Erstellen Sie eine Response wie in [Eine Response direkt zurückgeben](response-directly.md){.internal-link target=_blank} beschrieben und übergeben Sie die Header als zusätzlichen Parameter:

```Python hl_lines="10-12"
{!../../../docs_src/response_headers/tutorial001.py!}
```

!!! note "Technische Details"

## Retornar una `Response` directamente

Adicionalmente, puedes añadir headers cuando se retorne una `Response` directamente.

Crea un response tal como se describe en [Retornar una respuesta directamente](response-directly.md){.internal-link target=_blank} y pasa los headers como un parámetro adicional:

```Python hl_lines="10-12"
{!../../../docs_src/response_headers/tutorial001.py!}
```

!!! note "Detalles Técnicos"

👆 💪 📣 `Response` 🔢 🔗, & ⚒ 🎚 (& 🍪) 👫.

## 📨 `Response` 🔗

👆 💪 🚮 🎚 🕐❔ 👆 📨 `Response` 🔗.

✍ 📨 🔬 [📨 📨 🔗](response-directly.md){.internal-link target=_blank} & 🚶‍♀️ 🎚 🌖 🔢:

```Python hl_lines="10-12"
{!../../../docs_src/response_headers/tutorial001.py!}
```

!!! note "📡 ℹ"

}
```

#### Unwrapping a `dict`

If we take a `dict` like `user_dict` and pass it to a function (or class) with `**user_dict`, Python will "unwrap" it. It will pass the keys and values of the `user_dict` directly as key-value arguments.

So, continuing with the `user_dict` from above, writing:

```Python
UserInDB(**user_dict)
```

would result in something equivalent to:

```Python
UserInDB(

    - tutorial/debugging.md
  - Advanced User Guide:
    - advanced/index.md
    - advanced/path-operation-advanced-configuration.md
    - advanced/additional-status-codes.md
    - advanced/response-directly.md
    - advanced/custom-response.md
    - advanced/additional-responses.md
    - advanced/response-cookies.md
    - advanced/response-headers.md
    - advanced/response-change-status-code.md

# カスタムレスポンス - HTML、ストリーム、ファイル、その他のレスポンス

デフォルトでは、**FastAPI** は `JSONResponse` を使ってレスポンスを返します。

[レスポンスを直接返す](response-directly.md){.internal-link target=_blank}で見たように、 `Response` を直接返すことでこの挙動をオーバーライドできます。

しかし、`Response` を直接返すと、データは自動的に変換されず、ドキュメントも自動生成されません (例えば、生成されるOpenAPIの一部としてHTTPヘッダー `Content-Type` に特定の「メディアタイプ」を含めるなど) 。

しかし、*path operationデコレータ* に、使いたい `Response` を宣言することもできます。

*path operation関数* から返されるコンテンツは、その `Response` に含まれます。

    ```Python hl_lines="7"
    {!> ../../../docs_src/dependencies/tutorial011.py!}
    ```

In this case, **FastAPI** won't ever touch or care about `__init__`, we will use it directly in our code.

## Create an instance

We could create an instance of this class with:

=== "Python 3.9+"

    ```Python hl_lines="18"
    {!> ../../../docs_src/dependencies/tutorial011_an_py39.py!}
    ```

You only give `Depends` a single parameter.

This parameter must be something like a function.

You **don't call it** directly (don't add the parenthesis at the end), you just pass it as a parameter to `Depends()`.

And that function takes parameters in the same way that *path operation functions* do.

!!! tip