Cela comprend, par exemple :

* Les notifications par email envoyées après l'exécution d'une action :
    * Étant donné que se connecter à un serveur et envoyer un email a tendance à être «lent» (plusieurs secondes), vous pouvez retourner la réponse directement et envoyer la notification en arrière-plan.
* Traiter des données :

Vous pouvez y sélectionner "Releases only".

Ainsi, vous recevrez des notifications (dans votre courrier électronique) chaque fois qu'il y aura une nouvelle version de **FastAPI** avec des corrections de bugs et de nouvelles fonctionnalités.

## Se rapprocher de l'auteur

          * Read open questions until I find 2 where I can help someone and add a comment to help there.
          * I already hit the "watch" button in this repository to receive notifications and I commit to help at least 2 people that ask questions in the future.
          * Review one Pull Request by downloading the code and following [all the review process](https://fastapi.tiangolo.com/help-fastapi/#review-pull-requests).

This includes, for example:

* Email notifications sent after performing an action:
    * As connecting to an email server and sending an email tends to be "slow" (several seconds), you can return the response right away and send the email notification in the background.
* Processing data:

    if q:
        message = f"found query: {q}\n"
        background_tasks.add_task(write_log, message)
    return q


@app.post("/send-notification/{email}")
async def send_notification(
    email: str, background_tasks: BackgroundTasks, q: Annotated[str, Depends(get_query)]
):
    message = f"message to {email}\n"
    background_tasks.add_task(write_log, message)

client = TestClient(app)


def test():
    log = Path("log.txt")
    if log.is_file():
        os.remove(log)  # pragma: no cover
    response = client.post("/send-notification/******@****.***?q=some-query")
    assert response.status_code == 200, response.text
    assert response.json() == {"message": "Message sent"}
    with open("./log.txt") as f:

    client = TestClient(app)
    log = Path("log.txt")
    if log.is_file():
        os.remove(log)  # pragma: no cover
    response = client.post("/send-notification/******@****.***?q=some-query")
    assert response.status_code == 200, response.text
    assert response.json() == {"message": "Message sent"}
    with open("./log.txt") as f:

```Python hl_lines="14"
{!../../../docs_src/background_tasks/tutorial001.py!}
```

`.add_task()` は以下の引数を受け取ります:

* バックグラウンドで実行されるタスク関数 (`write_notification`)。
* タスク関数に順番に渡す必要のある引数の列 (`email`)。
* タスク関数に渡す必要のあるキーワード引数 (`message="some notification"`)。

## 依存性注入

`BackgroundTasks` の使用は依存性注入システムでも機能し、様々な階層 (*path operations 関数*、依存性 (依存可能性)、サブ依存性など) で `BackgroundTasks` 型のパラメーターを宣言できます。

## Test the app

Then we can just test the app as normally.

```Python hl_lines="32-47"
{!../../../docs_src/sql_databases/sql_app/tests/test_sql_app.py!}
```

    * Collect the money from the client.
    * Send a notification back to the API user (the external developer), as a callback.
        * At this point is that the API will somehow send a POST request to the
            external API with the notification of the invoice event
            (e.g. "payment successful").
    """
    # Send the invoice, collect the money, send the notification (the callback)