body:
  - type: markdown
    attributes:
      value: |
        Thanks for your interest in FastAPI! 🚀

        If you are not @tiangolo or he didn't ask you directly to create an issue here, please start the conversation in a [Question in GitHub Discussions](https://github.com/tiangolo/fastapi/discussions/categories/questions) instead.
  - type: checkboxes
    id: privileged
    attributes:
      label: Privileged issue

    Use the chat only for other general conversations.

### Don't use the chat for questions

Keep in mind that as chats allow more "free conversation", it's easy to ask questions that are too general and more difficult to answer, so, you might not receive answers.

    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}

!!! 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.
            """
        ),

    }
}
```

!!! note
    Notice that even though the `item` was declared the same way as before, it is now expected to be inside of the body with a key `item`.


**FastAPI** will do the automatic conversion from the request, so that the parameter `item` receives it's specific content and the same for `user`.

It will perform the validation of the compound data, and will document it like that for the OpenAPI schema and automatic docs.

### <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。

* 🐛 Fix overriding MKDocs theme lang in hook. PR [#10490](https://github.com/tiangolo/fastapi/pull/10490) by [@tiangolo](https://github.com/tiangolo).
* 🔥 Drop/close Gitter chat. Questions should go to GitHub Discussions, free conversations to Discord.. PR [#10485](https://github.com/tiangolo/fastapi/pull/10485) by [@tiangolo](https://github.com/tiangolo).

## 0.104.0

## Features