from fastapi import FastAPI, Query

app = FastAPI()


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

from fastapi import FastAPI

app = FastAPI()


@app.get("/items/", include_in_schema=False)
async def read_items():

	mu := NewDRWMutex(ds, "")
	if slack {
		b.SetParallelism(10)
	}
	b.RunParallel(func(pb *testing.PB) {
		foo := 0
		for pb.Next() {
			mu.Lock(id, source)
			mu.Unlock(b.Context())
			if work {
				for range 100 {
					foo *= 2
					foo /= 2
				}
			}
		}
		_ = foo
	})
}

func BenchmarkMutex(b *testing.B) {
	benchmarkMutex(b, false, false)
}

from fastapi import Body, FastAPI, status
from fastapi.responses import JSONResponse

app = FastAPI()

items = {"foo": {"name": "Fighters", "size": 6}, "bar": {"name": "Tenders", "size": 3}}


@app.put("/items/{item_id}")
async def upsert_item(
    item_id: str,
    name: str | None = Body(default=None),
    size: int | None = Body(default=None),
):
    if item_id in items:
        item = items[item_id]
        item["name"] = name

例如，声明 `X-Token` 多次出现的请求头，可以写成这样：

{* ../../docs_src/header_params/tutorial003_an_py310.py hl[9] *}

与*路径操作*通信时，以下面的方式发送两个 HTTP 请求头：

```
X-Token: foo
X-Token: bar
```

响应结果是：

```JSON
{
    "X-Token values": [
        "bar",
        "foo"
    ]
}
```

## 小结 { #recap }

使用 `Header` 声明请求头的方式与 `Query`、`Path` 、`Cookie` 相同。

app = FastAPI()


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

   * {@code Optional} class. However, this common usage:
   *
   * {@snippet :
   * for (Foo foo : possibleFoo.asSet()) {
   *   doSomethingWith(foo);
   * }
   * }
   *
   * ... can be replaced with:
   *
   * {@snippet :
   * possibleFoo.ifPresent(foo -> doSomethingWith(foo));
   * }
   *
   * <p><b>Java 9 users:</b> some use cases can be written with calls to {@code optional.stream()}.

        assertCollectorState(0, 0, 0, collector);

        assertEquals("foo-3.8.1", (out.getDependencies().get(0)).getVersion());
    }

    @Test
    public void testBasedir() throws Exception {
        Model model = new Model(org.apache.maven.api.model.Model.newBuilder()
                .version("3.8.1")
                .artifactId("foo")

from fastapi import FastAPI

app = FastAPI()


@app.get("/items/", operation_id="some_specific_id_you_define")
async def read_items():

    Integer foo = new Integer(Integer.MAX_VALUE - 10);
    Integer bar = new Integer(Integer.MAX_VALUE - 10);

    assertThat(foo).isNotSameInstanceAs(bar);
    assertThat(foo).isEqualTo(bar);

    List<Integer> list = asList(3, foo, bar, -1);
    List<Integer> result = numberOrdering.leastOf(list, list.size());
    assertEquals(ImmutableList.of(-1, 3, foo, bar), result);
  }