if !ok {
			return 0, errCastFailure("could not parse as int")
		}
		return res, nil
	case []byte:
		// Parse as number, truncate floating point if
		// needed.
		// String might contain trimming spaces, which
		// needs to be trimmed.
		res, ok := strToInt(strings.TrimSpace(string(x)))
		if !ok {
			return 0, errCastFailure("could not parse as int")
		}
		return res, nil

	default:

<span style="color: green;">INFO</span>:     Uvicorn running on http://127.0.0.1:8000 (Press CTRL+C to quit)
```

</div>

返回的响应如下：

```JSON
{
    "message": "Hello World",
    "root_path": "/api/v1"
}
```

### 在 FastAPI 应用里设置 `root_path`

还有一种方案，如果不能提供 `--root-path` 或等效的命令行选项，则在创建 FastAPI 应用时要设置 `root_path` 参数。

```Python hl_lines="3"

   *
   * <p>For example, if {@code rangeMap} had the entries {@code [1, 5] => "foo", (6, 8) => "bar",
   * (10, ∞) => "baz"} then {@code rangeMap.subRangeMap(Range.open(3, 12))} would return a range map
   * with the entries {@code (3, 5] => "foo", (6, 8) => "bar", (10, 12) => "baz"}.
   *
   * <p>The returned range map supports all optional operations that this range map supports, except

   */
  public static List<String> readLines(URL url, Charset charset) throws IOException {
    // don't use asCharSource(url, charset).readLines() because that returns
    // an immutable list, which would change the behavior of this method
    return readLines(
        url,
        charset,
        new LineProcessor<List<String>>() {
          final List<String> result = Lists.newArrayList();

          @Override

from docs_src.behind_a_proxy.tutorial004 import app

client = TestClient(app)


def test_main():
    response = client.get("/app")
    assert response.status_code == 200
    assert response.json() == {"message": "Hello World", "root_path": "/api/v1"}


def test_openapi_schema():
    response = client.get("/openapi.json")
    assert response.status_code == 200
    assert response.json() == {
        "openapi": "3.1.0",

     * @return The result of the settings building, never {@code null}.
     * @throws SettingsBuildingException If the effective settings could not be built.
     */
    SettingsBuildingResult build(SettingsBuildingRequest request) throws SettingsBuildingException;

		log.Errorf("unable to listen on socket: %v", err)
		return
	}
	exporter, err := monitoring.RegisterPrometheusExporter(nil, nil)
	if err != nil {
		log.Errorf("could not set up prometheus exporter: %v", err)
		return
	}
	mux.Handle(path, exporter)
	monitoringServer := &http.Server{
		Handler: mux,
	}
	go func() {

client = TestClient(app, root_path="/api/v1")


def test_main():
    response = client.get("/app")
    assert response.status_code == 200
    assert response.json() == {"message": "Hello World", "root_path": "/api/v1"}


def test_openapi():
    response = client.get("/openapi.json")
    assert response.status_code == 200
    assert response.json() == {
        "openapi": "3.1.0",

    /** */
    public int intField;

    /** */
    public String stringField;

    /** */
    public static final int INT_DATA = 987654321;

    /** */
    public static final String STRING_DATA = "Hello World!";

    /**
     * @throws Exception
     */
    @Test
    public void testGet() throws Exception {
        final Field field = getClass().getField("objectField");
        final Integer testData = new Integer(123);

prefix_router = APIRouter()
native_prefix_route = APIRouter(prefix="/native")
app = FastAPI()


@app.websocket_route("/")
async def index(websocket: WebSocket):
    await websocket.accept()
    await websocket.send_text("Hello, world!")
    await websocket.close()


@router.websocket_route("/router")
async def routerindex(websocket: WebSocket):
    await websocket.accept()
    await websocket.send_text("Hello, router!")