class CustomModel(BaseModel):
    a: int


app = FastAPI()

callback_router = APIRouter(default_response_class=JSONResponse)


@callback_router.get(
    "{$callback_url}/callback/", responses={400: {"model": CustomModel}}
)
def callback_route():
    pass  # pragma: no cover


@app.post("/", callbacks=callback_router.routes)
def main_route(callback_url: HttpUrl):
    pass  # pragma: no cover

### Einen Callback-`APIRouter` erstellen

Erstellen Sie zunächst einen neuen `APIRouter`, der einen oder mehrere Callbacks enthält.

```Python hl_lines="3  25"
{!../../../docs_src/openapi_callbacks/tutorial001.py!}
```

### Die Callback-*Pfadoperation* erstellen

⚫️ 🔜 ✔️ *➡ 🛠️* 👈 🔜 📨 `Invoice` 💪, & 🔢 🔢 `callback_url` 👈 🔜 🔌 📛 ⏲.

👉 🍕 📶 😐, 🌅 📟 🎲 ⏪ 😰 👆:

```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` ❌ *➡ 🛠️ 👨‍🎨*. 👥 🔜 👀 ⚫️❔ 👈 ⏭.

    ok: bool


invoices_callback_router = APIRouter()


@invoices_callback_router.post(
    "{$callback_url}/invoices/{$request.body.id}", response_model=InvoiceEventReceived
)
def invoice_notification(body: InvoiceEvent):
    pass


@app.post("/invoices/", callbacks=invoices_callback_router.routes)
def create_invoice(invoice: Invoice, callback_url: Union[HttpUrl, None] = None):
    """

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:

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

!!! tip

### 添加回调路由

至此，在上文创建的回调路由里就包含了*回调路径操作*（外部开发者要在外部 API 中实现）。

现在使用 API *路径操作装饰器*的参数 `callbacks`，从回调路由传递属性 `.routes`（实际上只是路由/路径操作的**列表**）：

```Python hl_lines="36"
{!../../../docs_src/openapi_callbacks/tutorial001.py!}
```

!!! tip "提示"

    注意，不能把路由本身（`invoices_callback_router`）传递给 `callback=`，要传递 `invoices_callback_router.routes` 中的 `.routes` 属性。

### 查看文档

                    },
                    "callbacks": {
                        "invoice_notification": {
                            "{$callback_url}/invoices/{$request.body.id}": {
                                "post": {
                                    "summary": "Invoice Notification",
                                    "operationId": "invoice_notification__callback_url__invoices___request_body_id__post",

ed-to-a-different-loop" class="external-link" target="_blank">MongoDBs MotorClient</a>), dann denken Sie daran, Objekte zu instanziieren, die einen Event Loop nur innerhalb asynchroner Funktionen benötigen, z. B. einen `@app.on_event("startup")`-Callback....

ns/41584243/runtimeerror-task-attached-to-a-different-loop" class="external-link" target="_blank">MongoDB's MotorClient</a>) Remember to instantiate objects that need an event loop only within async functions, e.g. an `'@app.on_event("startup")` callback....

    - advanced/testing-events.md
    - advanced/testing-dependencies.md
    - advanced/testing-database.md
    - advanced/async-tests.md
    - advanced/settings.md
    - advanced/openapi-callbacks.md
    - advanced/openapi-webhooks.md
    - advanced/wsgi.md
    - advanced/generate-clients.md
  - fastapi-cli.md
  - Deployment:
    - deployment/index.md
    - deployment/versions.md