# Histoire, conception et avenir

Il y a quelque temps, <a href="https://github.com/tiangolo/fastapi/issues/3#issuecomment-454956920" class="external-link" target="_blank">un utilisateur de **FastAPI** a demandé</a> :

> Quelle est l'histoire de ce projet ? Il semble être sorti de nulle part et est devenu génial en quelques semaines [...].

Voici un petit bout de cette histoire.

## Alternatives

    que des vérifications d'erreur, de l'auto-complétion, etc.

## <abbr title="aussi appelé sérialisation, ou parfois parsing ou marshalling en anglais">Conversion</abbr> de données

Si vous exécutez cet exemple et allez sur <a href="http://127.0.0.1:8000/items/3" class="external-link" target="_blank">http://127.0.0.1:8000/items/3</a>, vous aurez comme réponse :

```JSON
{"item_id":3}

    E.g. `pip install httpx`.

Import `TestClient`.

Create a `TestClient` by passing your **FastAPI** application to it.

Create functions with a name that starts with `test_` (this is standard `pytest` conventions).

Use the `TestClient` object the same way as you do with `httpx`.

Write simple `assert` statements with the standard Python expressions that you need to check (again, standard `pytest`).

!!! check
    This will give you editor support inside of your function, with error checks, completion, etc.

## Data <abbr title="also known as: serialization, parsing, marshalling">conversion</abbr>

If you run this example and open your browser at <a href="http://127.0.0.1:8000/items/3" class="external-link" target="_blank">http://127.0.0.1:8000/items/3</a>, you will see a response of:

```JSON
{"item_id":3}

### <a href="https://marshmallow.readthedocs.io/en/stable/" class="external-link" target="_blank">Marshmallow</a>

### <a href="https://marshmallow.readthedocs.io/en/stable/" class="external-link" target="_blank">🍭</a>

1️⃣ 👑 ⚒ 💪 🛠️ ⚙️ 📊 "<abbr title="also called marshalling, conversion">🛠️</abbr>" ❔ ✊ 📊 ⚪️➡️ 📟 (🐍) &amp; 🏭 ⚫️ 🔘 🕳 👈 💪 📨 🔘 🕸. 🖼, 🏭 🎚 ⚗ 📊 ⚪️➡️ 💽 🔘 🎻 🎚. 🏭 `datetime` 🎚 🔘 🎻, ♒️.

➕1️⃣ 🦏 ⚒ 💚 🔗 💽 🔬, ⚒ 💭 👈 💽 ☑, 🤝 🎯 🔢. 🖼, 👈 🏑 `int`, &amp; 🚫 🎲 🎻. 👉 ✴️ ⚠ 📨 💽.

            Read more about it in the
            [FastAPI docs for Header Parameters](https://fastapi.tiangolo.com/tutorial/header-params/#automatic-conversion)
            """
        ),
    ] = True,
    title: Annotated[
        Optional[str],
        Doc(
            """
            Human-readable title.
            """
        ),

And it will work and will be useful **during development**.

But if your connection to the server is lost, the **running process** will probably die.

### <a href="https://marshmallow.readthedocs.io/en/3.0/" class="external-link" target="_blank">Marshmallow</a>

APIシステムで必要とされる主な機能の一つに、コード (Python) からデータを取り出して、ネットワークを介して送れるものに変換するデータの「<abbr title="marshalling, conversion">シリアライゼーション</abbr>」があります。例えば、データベースのデータを含むオブジェクトをJSONオブジェクトに変換したり、`datetime` オブジェクトを文字列に変換するなどです。

Additionally, a background task is normally an independent set of logic that should be handled separately, with its own resources (e.g. its own database connection).