ここで、タスク関数はファイル書き込みを実行します (メール送信のシミュレーション)。

また、書き込み操作では `async` と `await` を使用しないため、通常の `def` で関数を定義します。

```Python hl_lines="6-9"
{!../../../docs_src/background_tasks/tutorial001.py!}
```

## バックグラウンドタスクの追加

*path operations 関数* 内で、`.add_task()` メソッドを使用してタスク関数を *background tasks* オブジェクトに渡します。

```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:

    ```

=== "Python 3.8+"

    ```Python hl_lines="9-11  14-15  18  19  23"
    {!> ../../../docs_src/generate_clients/tutorial001.py!}
    ```

Notice that the *path operations* define the models they use for request payload and response payload, using the models `Item` and `ResponseMessage`.

### API Docs

But here's the key point.

The security and dependency injection stuff is written once.

And you can make it as complex as you want. And still, have it written only once, in a single place. With all the flexibility.

But you can have thousands of endpoints (*path operations*) using the same security system.

│   ├── main.py
│   └── test_main.py
```

Let's say that now the file `main.py` with your **FastAPI** app has some other **path operations**.

It has a `GET` operation that could return an error.

It has a `POST` operation that could return several errors.

Both *path operations* require an `X-Token` header.

=== "Python 3.10+"

    ```Python
    {!> ../../../docs_src/app_testing/app_b_an_py310/main.py!}

* `POST`: to create data.
* `GET`: to read data.
* `PUT`: to update data.
* `DELETE`: to delete data.

So, in OpenAPI, each of the HTTP methods is called an "operation".

We are going to call them "**operations**" too.

#### Define a *path operation decorator*

```Python hl_lines="6"
{!../../../docs_src/first_steps/tutorial001.py!}
```

## 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.

And then you can also have a path `/users/{user_id}` to get data about a specific user by some user ID.

# GraphQL

As **FastAPI** is based on the **ASGI** standard, it's very easy to integrate any **GraphQL** library also compatible with ASGI.

You can combine normal FastAPI *path operations* with GraphQL on the same application.

!!! tip
    **GraphQL** solves some very specific use cases.

    It has **advantages** and **disadvantages** when compared to common **web APIs**.

            ),
        ] = None,
        scopes: Annotated[
            Optional[Dict[str, str]],
            Doc(
                """
                The OAuth2 scopes that would be required by the *path operations* that
                use this dependency.
                """
            ),
        ] = None,
        description: Annotated[
            Optional[str],
            Doc(
                """

Bất kì tích hợp nào được thiết kế để sử dụng đơn giản (với các dependency), đến nỗi bạn có thể tạo một "plug-in" cho ứng dụng của mình trong 2 dòng code bằng cách sử dụng cùng một cấu trúc và cú pháp được sử dụng cho *path operations* của bạn.

### Đã được kiểm thử

* 100% <abbr title=" Lượng code đã được kiểm thử tự động">test coverage</abbr>.

# レスポンスモデル

*path operations* のいずれにおいても、`response_model`パラメータを使用して、レスポンスのモデルを宣言することができます:

* `@app.get()`
* `@app.post()`
* `@app.put()`
* `@app.delete()`
* など。

```Python hl_lines="17"
{!../../../docs_src/response_model/tutorial001.py!}
```

!!! note "備考"
    `response_model`は「デコレータ」メソッド（`get`、`post`など）のパラメータであることに注意してください。すべてのパラメータやボディのように、*path operation関数* のパラメータではありません。