assertThat(routeSelector.hasNext()).isTrue()
    dns[PROXY_A_HOST] = dns.allocate(2)
    val selection1 = routeSelector.next()
    assertRoute(selection1.next(), address, proxyA, dns.lookup(PROXY_A_HOST, 0), PROXY_A_PORT)
    assertRoute(selection1.next(), address, proxyA, dns.lookup(PROXY_A_HOST, 1), PROXY_A_PORT)
    dns.assertRequests(PROXY_A_HOST)
    assertThat(selection1.hasNext()).isFalse()

In this case, the original path `/app` would actually be served at `/api/v1/app`.

Even though all your code is written assuming there's just `/app`.

```Python hl_lines="6"
{!../../../docs_src/behind_a_proxy/tutorial001.py!}
```

Auch wenn Ihr gesamter Code unter der Annahme geschrieben ist, dass es nur `/app` gibt.

```Python hl_lines="6"
{!../../../docs_src/behind_a_proxy/tutorial001.py!}
```

    并且 `--root-path` 命令行选项支持 `root_path`。

### 查看当前的 `root_path`

获取应用为每个请求使用的当前 `root_path`，这是 `scope` 字典的内容（也是 ASGI 规范的内容）。

我们在这里的信息里包含 `roo_path` 只是为了演示。

```Python hl_lines="8"
{!../../../docs_src/behind_a_proxy/tutorial001.py!}
```

然后，用以下命令启动 Uvicorn：

<div class="termy">

```console
$ uvicorn main:app --root-path /api/v1

## Beispiel

```python
from fastapi import FastAPI, status

app = FastAPI()


@app.get("/items/", status_code=status.HTTP_418_IM_A_TEAPOT)
def read_items():
    return [{"name": "Plumbus"}, {"name": "Portal Gun"}]
```

## Example

```python
from fastapi import FastAPI, status

app = FastAPI()


@app.get("/items/", status_code=status.HTTP_418_IM_A_TEAPOT)
def read_items():
    return [{"name": "Plumbus"}, {"name": "Portal Gun"}]
```

            return name

    async def get_model_c() -> ModelC:
        return ModelC(username="test-user", password="test-password")

    @app.get("/model/{name}", response_model=ModelA)
    async def get_model_a(name: str, model_c=Depends(get_model_c)):
        return {"name": name, "description": "model-a-desc", "foo": model_c}

    client = TestClient(app)
    return client


@needs_pydanticv2

### ✅ ⏮️ `root_path`

👆 💪 🤚 ⏮️ `root_path` ⚙️ 👆 🈸 🔠 📨, ⚫️ 🍕 `scope` 📖 (👈 🍕 🔫 🔌).

📥 👥 ✅ ⚫️ 📧 🎦 🎯.

```Python hl_lines="8"
{!../../../docs_src/behind_a_proxy/tutorial001.py!}
```

⤴️, 🚥 👆 ▶️ Uvicorn ⏮️:

<div class="termy">

```console
$ uvicorn main:app --root-path /api/v1

В этом случае `dependency_c` для выполнения своего кода выхода нуждается в том, чтобы значение из `dependency_b` (здесь `dep_b`) было еще доступно.

И, в свою очередь, `dependency_b` нуждается в том, чтобы значение из `dependency_a` (здесь `dep_a`) было доступно для ее завершающего кода.

=== "Python 3.9+"

    ```Python hl_lines="18-19  26-27"
    {!> ../../../docs_src/dependencies/tutorial008_an_py39.py!}
    ```

=== "Python 3.6+"

    {!> ../../../docs_src/dependencies/tutorial008.py!}
    ```

所有这些依赖都可以使用`yield`。

在这种情况下，`dependency_c` 在执行其退出代码时需要`dependency_b`（此处称为 `dep_b`）的值仍然可用。

而`dependency_b` 反过来则需要`dependency_a`（此处称为 `dep_a`）的值在其退出代码中可用。

=== "Python 3.9+"

    ```Python hl_lines="18-19  26-27"
    {!> ../../../docs_src/dependencies/tutorial008_an_py39.py!}
    ```

=== "Python 3.8+"