## Listen als Felder { #list-fields }

Sie können ein Attribut als Kindtyp definieren, zum Beispiel eine Python-`list`.

{* ../../docs_src/body_nested_models/tutorial001_py310.py hl[12] *}

Das bewirkt, dass `tags` eine Liste ist, wenngleich es nichts über den Typ der Elemente der Liste aussagt.

## Listen mit Typ-Parametern als Felder { #list-fields-with-type-parameter }

				panic(err)
			}
		}
	}
}

func getHosts(n int) (hosts []string, listeners []net.Listener, err error) {
	for range n {
		l, err := net.Listen("tcp", "127.0.0.1:0")
		if err != nil {
			if l, err = net.Listen("tcp6", "[::1]:0"); err != nil {
				return nil, nil, fmt.Errorf("httptest: failed to listen on a port: %v", err)
			}
		}
		addr := l.Addr()
		hosts = append(hosts, "http://"+addr.String())

	case <-listener.ctxDoneCh:
	}
	return nil, syscall.EINVAL
}

// Close - closes underneath all TCP listeners.
func (listener *httpListener) Close() (err error) {
	listener.ctxCanceler()

	for i := range listener.listeners {
		listener.listeners[i].Close()
	}

	return nil
}

from fastapi import FastAPI, Response, status

app = FastAPI()

tasks = {"foo": "Listen to the Bar Fighters"}


@app.put("/get-or-create-task/{task_id}", status_code=200)
def get_or_create_task(task_id: str, response: Response):
    if task_id not in tasks:
        tasks[task_id] = "This didn't exist before"
        response.status_code = status.HTTP_201_CREATED

client = TestClient(app)


def test_path_operation():
    response = client.put("/get-or-create-task/foo")
    print(response.content)
    assert response.status_code == 200, response.text
    assert response.json() == "Listen to the Bar Fighters"
    response = client.put("/get-or-create-task/bar")
    assert response.status_code == 201, response.text

## Liste von Modellen { #list-of-models }

Auf die gleiche Weise können Sie Responses von Listen von Objekten deklarieren.

Dafür verwenden Sie Pythons Standard-`typing.List` (oder nur `list` in Python 3.9 und höher):

{* ../../docs_src/extra_models/tutorial004_py39.py hl[18] *}

Probably in many cases the default will be that the proxy doesn't have a stripped path prefix.

In a case like that (without a stripped path prefix), the proxy would listen on something like `https://myawesomeapp.com`, and then if the browser goes to `https://myawesomeapp.com/api/v1/app` and your server (e.g. Uvicorn) listens on `http://127.0.0.1:8000` the proxy (without a stripped path prefix) would access Uvicorn at the same path: `http://127.0.0.1:8000/api/v1/app`.

		}
		return nil
	})
}

// Listen - listen on peers.
func (client *peerRESTClient) Listen(ctx context.Context, listenCh chan<- []byte, v url.Values) {
	go func() {
		for {
			client.doListen(ctx, listenCh, v)
			select {
			case <-ctx.Done():
				return
			default:
				// There was error in the REST request, retry after sometime as probably the peer is down.
				time.Sleep(5 * time.Second)
			}
		}

Here are some possible combinations and strategies:

* **Uvicorn** with `--workers`
    * One Uvicorn **process manager** would listen on the **IP** and **port**, and it would start **multiple Uvicorn worker processes**.
* **Kubernetes** and other distributed **container systems**
    * Something in the **Kubernetes** layer would listen on the **IP** and **port**. The replication would be by having **multiple containers**, each with **one Uvicorn process** running.

Aber standardmäßig **„funktioniert einfach alles“**.

### Validierung { #validation }

* Validierung für die meisten (oder alle?) Python-**Datentypen**, hierzu gehören:
    * JSON Objekte (`dict`).
    * JSON Listen (`list`), die den Typ ihrer Elemente definieren.
    * Strings (`str`) mit definierter minimaler und maximaler Länge.
    * Zahlen (`int`, `float`) mit Mindest- und Maximalwerten, usw.