* Annotations d'API et documentation automatique.

Et vous n'avez besoin de le déclarer qu'une fois.

```Python hl_lines="9-13  36-53"
{!../../../docs_src/openapi_callbacks/tutorial001.py!}
```

!!! tip
     `callback_url` 🔢 🔢 ⚙️ Pydantic <a href="https://docs.pydantic.dev/latest/concepts/types/#urls" class="external-link" target="_blank">📛</a> 🆎.

🕴 🆕 👜 `callbacks=messages_callback_router.routes` ❌ *➡ 🛠️ 👨‍🎨*. 👥 🔜 👀 ⚫️❔ 👈 ⏭.

## 🔬 ⏲

☑ ⏲ 📟 🔜 🪀 🙇 🔛 👆 👍 🛠️ 📱.

Now, for FastAPI, it will see the return type and make sure that what you return includes **only** the fields that are declared in the type.

FastAPI does several things internally with Pydantic to make sure that those same rules of class inheritance are not used for the returned data filtering, otherwise you could end up returning much more data than what you expected.

Das kann nützlich sein, wenn Sie beispielsweise in einem Land leben, in dem bestimmte URLs eingeschränkt sind.

### Die automatischen Dokumentationen deaktivieren

Der erste Schritt besteht darin, die automatischen Dokumentationen zu deaktivieren, da diese standardmäßig das Standard-CDN verwenden.

Um diese zu deaktivieren, setzen Sie deren URLs beim Erstellen Ihrer `FastAPI`-App auf `None`:

```Python hl_lines="8"

# Metadata and Docs URLs

You can customize several metadata configurations in your **FastAPI** application.

## Metadata for API

You can set the following fields that are used in the OpenAPI specification and the automatic API docs UIs:

| Parameter | Type | Description |
|------------|------|-------------|
| `title` | `str` | The title of the API. |

## OpenAPI 自定义 URL

要自定义 OpenAPI 的 URL（或删除它），请阅读 [教程 - 元数据和文档 URL](../tutorial/metadata.md#openapi-url){.internal-link target=_blank} 文档。

## OpenAPI 文档 URL

    "Topic :: Internet :: WWW/HTTP",
]
dependencies = [
    "starlette>=0.37.2,<0.38.0",
    "pydantic>=1.7.4,!=1.8,!=1.8.1,!=2.0.0,!=2.0.1,!=2.1.0,<3.0.0",
    "typing-extensions>=4.8.0",
]

[project.urls]
Homepage = "https://github.com/tiangolo/fastapi"
Documentation = "https://fastapi.tiangolo.com/"
Repository = "https://github.com/tiangolo/fastapi"

[project.optional-dependencies]

standard = [

* 📝 Tweak and improve docs for Request Files. PR [#4470](https://github.com/tiangolo/fastapi/pull/4470) by [@tiangolo](https://github.com/tiangolo).

### Fixes

* 🐛 Fix bug preventing to use OpenAPI when using tuples. PR [#3874](https://github.com/tiangolo/fastapi/pull/3874) by [@victorbenichoux](https://github.com/victorbenichoux).

## To `async` or not to `async`

As dependencies will also be called by **FastAPI** (the same as your *path operation functions*), the same rules apply while defining your functions.

You can use `async def` or normal `def`.

### Don't worry about style

* Don't worry too much about things like commit message styles, I will squash and merge customizing the commit manually.

* Also don't worry about style rules, there are already automatized tools checking that.

And if there's any other style or consistency need, I'll ask directly for that, or I'll add commits on top with the needed changes.

### Check the code