```Python hl_lines="35"
{!../../docs_src/openapi_callbacks/tutorial001.py!}
```

/// tip | "Tipp"

Beachten Sie, dass Sie nicht den Router selbst (`invoices_callback_router`) an `callback=` übergeben, sondern das Attribut `.routes`, wie in `invoices_callback_router.routes`.

///

### Es in der Dokumentation ansehen

* Es gibt ein Unterverzeichnis `app/routers/` mit einer weiteren Datei `__init__.py`, es handelt sich also um ein „Python-Subpackage“: `app.routers`.
* Die Datei `app/routers/items.py` befindet sich in einem Package, `app/routers/`, also ist sie ein Submodul: `app.routers.items`.
* Das Gleiche gilt für `app/routers/users.py`, es ist ein weiteres Submodul: `app.routers.users`.

* There's a subdirectory `app/routers/` with another file `__init__.py`, so it's a "Python subpackage": `app.routers`.
* The file `app/routers/items.py` is inside a package, `app/routers/`, so, it's a submodule: `app.routers.items`.
* The same with `app/routers/users.py`, it's another submodule: `app.routers.users`.

        if responses is None:
            responses = {}
        for route in router.routes:
            if isinstance(route, APIRoute):
                combined_responses = {**responses, **route.responses}
                use_response_class = get_value_or_default(
                    route.response_class,
                    router.default_response_class,
                    default_response_class,

* 📤 `app/dependencies.py` 📁, 💖 `app/main.py`, ⚫️ "🕹": `app.dependencies`.
* 📤 📁 `app/routers/` ⏮️ ➕1️⃣ 📁 `__init__.py`, ⚫️ "🐍 📦": `app.routers`.
* 📁 `app/routers/items.py` 🔘 📦, `app/routers/`,, ⚫️ 🔁: `app.routers.items`.
* 🎏 ⏮️ `app/routers/users.py`, ⚫️ ➕1️⃣ 🔁: `app.routers.users`.
* 📤 📁 `app/internal/` ⏮️ ➕1️⃣ 📁 `__init__.py`, ⚫️ ➕1️⃣ "🐍 📦": `app.internal`.

* Há um subdiretório `app/routers/` com outro arquivo `__init__.py`, então ele é um "subpacote Python": `app.routers`.
* O arquivo `app/routers/items.py` está dentro de um pacote, `app/routers/`, portanto, é um "submódulo": `app.routers.items`.
* O mesmo com `app/routers/users.py`,  ele é outro submódulo: `app.routers.users`.

* 还有一个 `app/dependencies.py` 文件，就像 `app/main.py` 一样，它是一个「模块」：`app.dependencies`。
* 有一个子目录 `app/routers/` 包含另一个 `__init__.py` 文件，因此它是一个「Python 子包」：`app.routers`。
* 文件 `app/routers/items.py` 位于 `app/routers/` 包中，因此它是一个子模块：`app.routers.items`。
* 同样适用于 `app/routers/users.py`，它是另一个子模块：`app.routers.users`。
* 还有一个子目录 `app/internal/` 包含另一个 `__init__.py` 文件，因此它是又一个「Python 子包」：`app.internal`。

{!../../docs_src/custom_request_and_route/tutorial002.py!}
```

## Custom `APIRoute` class in a router

You can also set the `route_class` parameter of an `APIRouter`:

```Python hl_lines="26"
{!../../docs_src/custom_request_and_route/tutorial003.py!}
```

///

### Add the callback router

At this point you have the *callback path operation(s)* needed (the one(s) that the *external developer*  should implement in the *external API*) in the callback router you created above.

Now use the parameter `callbacks` in *your API's path operation decorator* to pass the attribute `.routes` (that's actually just a `list` of routes/*path operations*) from that callback router:

  [entryPoints.http]
    address = ":9999"

[providers]
  [providers.file]
    filename = "routes.toml"
```

👉 💬 Traefik 👂 🔛 ⛴ 9️⃣9️⃣9️⃣9️⃣ & ⚙️ ➕1️⃣ 📁 `routes.toml`.

/// tip

👥 ⚙️ ⛴ 9️⃣9️⃣9️⃣9️⃣ ↩️ 🐩 🇺🇸🔍 ⛴ 8️⃣0️⃣ 👈 👆 🚫 ✔️ 🏃 ⚫️ ⏮️ 📡 (`sudo`) 😌.

///

🔜 ✍ 👈 🎏 📁 `routes.toml`:

```TOML hl_lines="5  12  20"
[http]
  [http.middlewares]