builder.put("foo", 2);
    assertMapEquals(builder.buildOrThrow(), "foo", 2);
  }

  public void testBuilderPutImmutableEntryWithNullKeyFailsAtomically() {
    Builder<String, Integer> builder = new Builder<>();
    assertThrows(NullPointerException.class, () -> builder.put(immutableEntry((String) null, 1)));
    builder.put("foo", 2);
    assertMapEquals(builder.buildOrThrow(), "foo", 2);

            min_length=3,
            max_length=50,
            pattern="^fixedquery$",
            deprecated=True,
        ),
    ] = None,
):
    results = {"items": [{"item_id": "Foo"}, {"item_id": "Bar"}]}
    if q:
        results.update({"q": q})

            description="Query string for the items to search in the database that have a good match",
            min_length=3,
        ),
    ] = None,
):
    results = {"items": [{"item_id": "Foo"}, {"item_id": "Bar"}]}
    if q:
        results.update({"q": q})

    price: float
    tax: Union[float, None] = None


@app.put("/items/{item_id}")
async def update_item(
    item_id: int,
    item: Item = Body(
        examples=[
            {
                "name": "Foo",
                "description": "A very nice Item",
                "price": 35.4,
                "tax": 3.2,
            }
        ],
    ),
):
    results = {"item_id": item_id, "item": item}

from fastapi import FastAPI

app = FastAPI()


@app.get("/keyword-weights/", response_model=dict[str, float])
async def read_keyword_weights():

public final class Throwables {
  private Throwables() {}

  /**
   * Throws {@code throwable} if it is an instance of {@code declaredType}. Example usage:
   *
   * <pre>
   * for (Foo foo : foos) {
   *   try {
   *     foo.bar();
   *   } catch (BarException | RuntimeException | Error t) {
   *     failure = t;
   *   }
   * }
   * if (failure != null) {
   *   throwIfInstanceOf(failure, BarException.class);

foo iRFmWghs3CK9/2HSvRja4TzX8HsRwzbVY+h0HRkH9uPho2BGmrG5a0/+rkLSA3GUOX/WiPmP+h73T1r0DZIDJXtOgYWIU/y2H+WAe/ZlWt90N2KHka0bkXajoE/3mu7jiCW45hTNBDp3ArJ+K8Oh6bEfN2bHhXjZ41Zk+uvksVba2ZNyhThAAGZgi/pRa/oCT4HUoBWcY3w96+TGR6uXtvbDOM9WhPXGo+1bwhAsA/RXPA1ZX+oS6t4rl/ZvkMZZN4VO5OvKph8tth/BGEK6mw4oTRa1Hd91+bUUqQh6hl3JeDk/t2KDWOEehOxgOqfVG72U/pUXrcUXuywq9KT+bWQxdJsXzwkkyT8Ovz4o/Ib8Xxz+BHwpN3TtOXsHziuqLGMz+OxetaxhQqe1G/UWwfi5a9PuJC3wfITSa0=...

from fastapi import FastAPI, Query

app = FastAPI()


@app.get("/items/")
async def read_items(
    q: Annotated[Union[str, None], Query(min_length=3, max_length=50)] = None,
):
    results = {"items": [{"item_id": "Foo"}, {"item_id": "Bar"}]}
    if q:
        results.update({"q": q})

app = FastAPI()


@app.get("/items/")
async def read_items(
    q: Annotated[
        str | None, Query(min_length=3, max_length=50, regex="^fixedquery$")
    ] = None,
):
    results = {"items": [{"item_id": "Foo"}, {"item_id": "Bar"}]}
    if q:
        results.update({"q": q})

```Python hl_lines="11"
{!../../docs_src/handling_errors/tutorial001.py!}

```

### 响应结果

请求为 `http://example.com/items/foo`（`item_id` 为 `「foo」`）时，客户端会接收到 HTTP 状态码 - 200 及如下 JSON 响应结果：

```JSON
{
  "item": "The Foo Wrestlers"
}

```

但如果客户端请求 `http://example.com/items/bar`（`item_id` `「bar」` 不存在时），则会接收到 HTTP 状态码 - 404（「未找到」错误）及如下 JSON 响应结果：

```JSON
{