route.address.url.toUri(),
          route.proxy.address(),
          e,
        )
      }
      call.eventListener.connectFailed(call, route.socketAddress, route.proxy, null, e)
      connectionPool.connectionListener.connectFailed(route, call, e)
      return ConnectResult(plan = this, throwable = e)
    } finally {
      call.plansToCancel -= this
      if (!success) {

///

### Agrega el router de callback { #add-the-callback-router }

En este punto tienes las *path operation(s)* del callback necesarias (las que el *desarrollador externo* debería implementar en la *API externa*) en el router de callback que creaste arriba.

## Classe `APIRoute` personalizada em um router { #custom-apiroute-class-in-a-router }

Você também pode definir o parâmetro `route_class` de uma `APIRouter`:

{* ../../docs_src/custom_request_and_route/tutorial003_py310.py hl[26] *}

        operation["tags"] = route.tags
    operation["summary"] = generate_operation_summary(route=route, method=method)
    if route.description:
        operation["description"] = route.description
    operation_id = route.operation_id or route.unique_id
    if operation_id in operation_ids:
        endpoint_name = getattr(route.endpoint, "__name__", "<unnamed_endpoint>")

///

### 避免名稱衝突 { #avoid-name-collisions }

我們直接匯入子模組 `items`，而不是只匯入它的變數 `router`。

這是因為在子模組 `users` 中也有另一個名為 `router` 的變數。

如果我們像下面這樣一個接一個匯入：

```Python
from .routers.items import router
from .routers.users import router
```

來自 `users` 的 `router` 會覆蓋掉 `items` 的 `router`，我們就無法同時使用兩者。

因此，為了能在同一個檔案中同時使用它們，我們直接匯入子模組：

///

### 加入回呼 router { #add-the-callback-router }

此時你已經在先前建立的回呼 router 中，擁有所需的回呼「路徑操作（們）」（也就是「外部開發者」應該在「外部 API」中實作的那些）。

現在在「你的 API 的路徑操作裝飾器」中使用參數 `callbacks`，將該回呼 router 的屬性 `.routes`（實際上就是一個由路由／「路徑操作」所組成的 `list`）傳入：

{* ../../docs_src/openapi_callbacks/tutorial001_py310.py hl[33] *}

/// tip

    http2Connection.start()
  }

  /**
   * Returns true if this connection can carry a stream allocation to `address`. If non-null
   * `route` is the resolved route for a connection.
   */
  internal fun isEligible(
    address: Address,
    routes: List<Route>?,
  ): Boolean {
    assertLockHeld()

    // If this connection is not accepting new exchanges, we're done.

    dns.assertRequests(uriHost)
    val routes = selection.routes
    assertRoute(routes[0], address, Proxy.NO_PROXY, dns.lookup(uriHost, 0), uriPort)
    assertRoute(routes[1], address, Proxy.NO_PROXY, dns.lookup(uriHost, 1), uriPort)
    assertThat(selection.next()).isSameInstanceAs(routes[0])
    assertThat(selection.next()).isSameInstanceAs(routes[1])
    assertThat(selection.hasNext()).isFalse()

  val failedRoutes: Set<Route>
    @Synchronized get() = _failedRoutes.toSet()

  /** Records a failure connecting to [failedRoute]. */
  @Synchronized fun failed(failedRoute: Route) {
    _failedRoutes.add(failedRoute)
  }

  /** Records success connecting to [route]. */
  @Synchronized fun connected(route: Route) {
    _failedRoutes.remove(route)
  }

## Benutzerdefinierte `APIRoute`-Klasse in einem Router { #custom-apiroute-class-in-a-router }

Sie können auch den Parameter `route_class` eines `APIRouter` festlegen:

{* ../../docs_src/custom_request_and_route/tutorial003_py310.py hl[26] *}